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Fuel Pump and
Fuel Pump Relay Page


Updated: June 27, 2022     CONTACT
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N A V I G A T E   T H I S   P A G E
Fuel Pump Relay Diagrams
Bosch LH EFI Pin Function Diagrams
LH Conversion Fuel Pump Power
LH ECU Common Failure
Universal Fuel Pump Controller
VW Fuel Pump Relay
Inner Workings: K-Jet Relay
Repairing a K-Jet Relay
Inner Workings: LH-Jet Relay
Removing Relay Plug Terminals
Jumping a Fuel Pump Relay
Adding Secondary Relay: K-Jet
Adding Secondary Relay: LH-Jet
Inertia Switch
Using Common Relays Instead of the WHITE Relay?
240 IN TANK PUMP R and R
Fuel Pump Check Valve
Anti-Corrosive Zinc Paste

If you can help with these diagrams or have a suggestion, please email:  CONTACT


Simplified description of Early Volvo 240 Fuel Pump Relay Function
The early Volvo 240 with Bosch K-Jetronic (up to 1977) used an airflow sensor switch. This switch was inside the Air/Fuel Control Unit, which would cut off power to the fuel pump if no engine airflow was detected. This system used two relays, one for fuel pump and one for fuel injection system.



Beginning in 1978, Volvo adopted the below style of fuel pump relay for K-Jetronic to replace the previous dual fuel system relays. This new style of relay added a PULSE SENSOR, which read ignition pulses. Ignition pulses are the same as a tachometer signal and they are generated by the ignition coil while the engine is running. Since these pulses are only produced when the engine is turning, this added a level of safety, because the new relay would only allow the fuel pumps to pump or pressurize fuel lines when the engine was running. So in a crash, assuming the engine has stopped, the fuel pumps
and fuel lines would no longer be feeding pressurized fuel.


Volvo continued using this type of relay for fuel injected cars using Bosch K-Jetronic.
Later Volvo would begin using Bosch LH Jetronic, which no longer needed a relay that could read a tachometer signal. Beginning in 1985, the well-known White Stribel fuel relay began appearing in LH EFI cars. This white relay no longer had a function to read a tachometer signal. Instead, this function became the job of the EFI ECU instead.  



Typical 240, 740, 940 Fuel Pump Wiring Circuits

240 Fuel pump and fuel pump relay circuits can be a mystery.  Here are diagrams showing how they were done over the years. 


1977 240 K-Jet

1978 240 K-Jet


1982 240 K-Jet


1984 240 K-Jet Turbo


1984 240 LH 2.0


1987 240 LH 2.2


1993 240 LH 2.4

1987 740 LH 2.2


1989 740 CI K-Jet B200/230E

1989 740 LH 2.2 B230FT

1989 740 LH 2.4 B230F

1989 740 Motronic B200/B230ET

1989 740 REGINA B234F USA Federal

1989 740 LH 2.4 B234F B204E



1994 940 LH 2.4
B200F/G, B230F/FB/FD/G

1994 940 REGINA B230F

  More detailed PIN-FUNCTION DIAGRAMS for most 240 Fuel Injection systems can be found in my Harness Page:
https://www.prancingmoose.com/volvoharnesses.html#pinfunctions



FUEL PUMP POWER FOR
LH 2.2 or LH 2.4 +EZK 240 CONVERSION HARNESSES

This image below is intended to address questions about how power is typically provided to the fuel pumps when installing an LH 2.2 or 2.4 +EZK 240 Conversion Harness in a 240 Turbo or other early 240, which originally had K-Jetronic fuel injection. 
These is more than one way to do this kind of thing, but here I suggest a simple solution. 

CLICK IMAGE FOR LARGER PHOTO





Universal Fuel Pump Controller
(using a Tach Signal for activation)
  
You may have a need for a universal fuel pump controller, which will receive your ignition coil or tach signal and then reliably activate your fuel pump(s). 
This controller is designed to prime the pump for 5 seconds upon first power-up. After that it will run the pump until the engine stops or is turned off.

Why would you ever need a controller like this?
If you have a car that needs a TACH PULSE SIGNAL to turn on the fuel pump relay (as discussed HERE), like in any Volvo 240 after 1978, or 740 or 940, and for any reason the factory activation circuit in your fuel injection relay or your ECU is no longer functioning like it should, then a device like this can save the day. 

CAUTION: Be sure to first check that your relay or ECU is actually RECEIVING the tach pulse signal. If it's not, your failure COULD be in the ignition system instead. You can test this by jumping the fuel pumps to force them to run (MORE HERE). If the car runs when jumped, then your ignition is probably fine.

Common Failures in a K-Jet Pump Relay.
 
For a 240 Turbo or non-turbo with K-Jet injection, the factory Stribel fuel pump relay requires an ignition pulse signal to turn "ON."  This relay is known to become a bit finicky about accepting the tach signal, especially if you have done any changes to the ignition, such as adding an ignition amplifier (i.e; MSD) or when changing to a different (non-Volvo) engine management system.

Common Failures in a Bosch EFI Fuel ECU.
For a later 240 or other EFI Volvo (using Bosch LH 2.0, 2.2 or 2.4), the ignition tach pulse signal must be received by the fuel injection ECU (NOT the relay).  The ECU then processes that signal and converts it to a CONTROL SIGNAL. This Control Signal is a GROUND signal, which is sent from the ECU to the fuel pump relay to turn it  "ON" and activate the pumps.

Bosch fuel injection ECUs rarely fail, except for the more frequent fault of losing the ability to process or convert this tach signal. When that happens, the fuel pump relay won't turn on when the engine is spinning like it's supposed to. Replacing the ECU may be a solution, however, if you've determined that your ECU has this particular failure and is otherwise OK, then this is a simple work-around.  Installing a universal fuel pump controller will solve this problem without the need to replace your expensive ECU.



This image below is a 240 with Bosch LH 2.2 (1985-88).
That BLUE/GREEN wire shown below is what transmits the control GROUND signal from the ECU to the relay. This signal is simply a GROUND sent to Relay Pin 86/2 to close the circuit and turn the fuel pump circuit "ON." When your ECU fails to activate that signal, your fuel relay does not turn on and neither do your fuel pumps.
WARNING: If you're testing this GROUND signal, absolutely NEVER connect voltage to it.
More Pin Function Diagrams like this are available for a number of different Volvos HERE.




This image below is a 240 with Bosch LH 2.4 (1989-93).
That BLUE/GREEN wire shown below is what transmits the control GROUND signal from the ECU to the relay. This signal is simply a GROUND sent to Relay Pin 86/2 to close the circuit and turn the fuel pump circuit "ON." When your ECU fails to activate that signal, your fuel relay does not turn on and neither do your fuel pumps.
WARNING: If you're testing that GROUND signal, absolutely NEVER connect voltage to it.
 More Pin Function Diagrams like this are available for a number of different Volvos HERE.

 
More specific info on wiring a universal fuel pump controller is a bit further BELOW.



The below video offers a demonstration of how to connect a GROUND TEST WIRE to your LH 2.2 or LH 2.4 240 Fuel Pump Relay. This acts as a diagnostic test for a car that won't start and if you suspect the Fuel Pump Relay is not being activated by the ECU when the engine is turning.

The ground wire should be connected to the BLUE/GREEN wire going to the relay plug. Grounding the Blue/Green wire in this test simply replicates what the ECU is supposed to do when it activates the relay.

https://www.youtube.com/watch?v=f2tCRejgFoU&feature=emb_logo




Universal Fuel Pump Controller from Revolution Electronics
https://www.revolutionelectronics.com/

The manufacturer's standard installation instructions and wiring can be found here: https://www.revolutionelectronics.com/12003-installation-2.pdf

While the above PDF instructions will explain the STANDARD installation using the controllers POWER output to power your pump(s), I don't recommend using this controller to directly power a fuel pump. It would be a better idea to have this controller activate a relay, which will then reliably supply direct battery power to the fuel pumps.

While the manufacturer's diagram calls for the output from the controller to be POWER, it does not need to be wired that way.  This controller can also be configured to use a GROUND OUTPUT.  Using a ground to trigger a relay is my preference and this is also always how it was done in a Volvo. 

Why would you care about using a relay like I suggest?

Because using a separate relay as shown below would also give you the opportunity to add an optional PRIME/OVERRIDE switch in your dash.  This is how my 240 Turbo is wired using this controller for my stand-alone fuel pump activation device.

SIMPLIFIED UNIVERSAL CONTROLLER DIAGRAM
If you're confused by the TWO purple wires, think of those as one wire going IN to a switch and the other going OUT from the switch.
When wiring this controller, it doesn't matter which (purple) wire is used for IN or OUT. More detailed diagrams are further below.
The fuel pump PRIME/OVERRIDE SWITCH shown below is an option that you can add if you want to.



If you want to use a universal fuel pump controller to solve the ECU
TACH PULSE SIGNAL issue mentioned above, then the below more specific diagrams can be used to install this device.

For the Bosch LH 2.0 diagram below (1983-84 240) there are two fuel injection relays. If you're not sure which one of those is the fuel pump relay, you can compare the wire colors to the diagram below.

In the wiring configuration below, the universal fuel pump controller PURPLE wires are set up as a ground switch circuit.  One of the PURPLE wires goes to ground and the other becomes an output and gets connected to the respective relay circuit to trigger the relay "ON."  Using this diagram, it does not matter which PURPLE wire from the controller goes to ground.
 
The GREEN wire feeds your tach pulse signal to the universal controller, so it may be connected to or spliced to your tachometer signal wire, to coil terminal 1 (negative), or to the wire going to terminal #1 of the LH ECU.
The RED wire needs to be connected to any 12v power that is switched 'ON' when the key is in the 'RUN' position. The wires shown below being connected to the RED WIRE will accomplish that for you. 
NOTE: This controller is designed to prime the pumps for 5 seconds when the key is first turned to 'RUN.'


SUGGESTED VOLVO SPECIFIC DIAGRAMS

Universal Controller Diagram for 240 with LH 2.0 or 2.2.
To restore tach pulse signal function.

Universal Controller Diagram for 240 or 740 with LH 2.4.
To restore tach pulse signal function.




VW/Audi Fuel Pump Relay
(using a Tach Signal for activation)
Here's an interesting existing VW fuel pump relay that will do a similar function as the above universal controller. It's much less expensive.
I have NOT tried one of these, but I would probably have considered trying one if I had discovered it before buying the universal controller above. 
This relay is designed to receive a coil/tach pulse signal to activate a fuel pump circuit.
 

This relay is easily found on line and there are a few different versions.  VW PN 321906059C will have an integrated fuse on top. Some versions will have a ceramic fuse like the middle photo below. The one of the right is an aftermarket relay from KAE and it has a blade fuse. There are also versions without any integrated fuse, such as PN 321906069D, G or H. 
This relay does not offer a timed pump priming feature. It just turns the pumps on or off.


This diagram below shows a simplified installation. The tachometer signal may be used from the tach signal lead or from terminal 1 (negative) of the coil.


Here's a diagram below showing how this relay can be used with a ground output to control a second relay. Why would you do that?  I'll tell you why. This will allow the use of an optional pump Prime/Override switch.







Inner Workings of the K-Jetronic Fuel Pump Relay
Volvo PN 3523639
Used in 240 DL, GL 1978-82 with K-Jetronic Fuel Injection, 240 Turbo 1981-85 all years, 260 1978-82, 760 V6 only with K-Jetronic.






Repairing a Bad K-Jetronic Fuel Pump Relay
There is a fairly common fault in this fuel pump relay. Over the years the solder joints on the back of the board can develop small cracks. This is most likely due to a combination of vibration and heat cycles. The cracks can usually be seen if you look very close or use a magnifying glass. These cracks will cause intermittent problems.

The most common cracks seem to be where the RED circles are below. The three RED circles are the points where the coil frame is anchored to the board. In particularly bad cases these cracks can cause the coil to rattle around on its mounting points if you shake the relay. The coil frame is connected to Pin 30.

The less common places to watch for cracks are the other colored circles. The YELLOW circles are connected to Pin 87b and the BLUE circle is connected to Pin 87.

You can use a simple soldering iron to heat and re-flow the solder at any point you suspect might be cracked.  This will cure any issue that was caused by a crack. 

Here's a good basic video on soldering on a circuit board.
https://www.youtube.com/watch?v=DJH7VLGJ4fs







Inner Workings of the LH 2.2 and 2.4 Fuel Pump Relay
Volvo PN 3523608 (previous 1347603)
Used in 240 DL/GL 85-93 (LH-Jetronic 2.2 and 2.4), 740 85-92 turbo and non-turbo, 760 87 6-cylinder, 780 87-91 all (4 cyl turbo and 6 cyl), 940 non-turbo 91-93, 940 Turbo 91-95 (except for 1991-93 940 SE).
The below diagram is typical of a 1985-1993 240 relay.  The 740 uses the same relay, but keep in mind that some 700 cars swapped sides for the Fuel System Function and Fuel Pump Function.  So in some 700 cars, the power output pins may be swapped.
This relay was used for LH 2.2 cars and LH 2.4 cars.  This relay has two coils and is essentially two relays in one case to control two separate functions;
1. Fuel Pump Power.
2. Main Fuel System Power.

It has similar functions as the earlier LH 2.0 relays (two separate cube relays used in the 1983-84 240 non-turbo).

LH Jetronic 2.2
LH 2.2 ECU Pin Function Diagrams may be found here if needed.
 LH 2.2 came in 240 (non-turbo) from 1985-1988, 740 (non-turbo) from 1985-1988, 700 Turbo from 1984-1989.
Exceptions: Some non-U.S. markets got K-Jet models during these years.
Fuel Pump Function:
In the case of LH 2.2, the fuel injection ECU receives a coil/tach signal (at ECU Pin 1) when the engine is running.  The ECU then converts that signal to a ground (or control signal) and sends it out from ECU Pin 17 to LH relay Pin 86/2.
The LH 2.2 ECU also sends battery power out through ECU Pin 18 and then into LH relay Pin 85. 

The ground from Pin 86/2 and power from Pin 85
completes the circuit to activate the fuel pump relay coil, closing the contacts and sending battery power from relay Pin 30 internally to relay Pin 87/2, which is the output for Fuel Pumps, Oxygen Sensor (heater), Fuel Injectors and Idle Valve.

Main Fuel System Function: In the case of LH 2.2, the fuel injection ECU sends a ground (control signal) out from ECU Pin 21 to LH relay Pin 86/1.  The Main Fuel System coil receives battery power from the relay Pin 30 circuit. These circuits activate the coil, closing the contacts and sending battery power from relay Pin 30 internally to relay Pin 87/1, which is the output for power to the MAF (AMM) and for power to ECU Pin 9.
LH Relay Pin 30 gets battery power directly from the LH Fuse located on the 240 front left inner fender. In cars that don't have this fuse (such as a 700 non-turbo to 1988, 700 Turbo to 1989), Pin 30 gets power from the ignition switch (Terminal 29).



LH Jetronic 2.4
LH 2.4 ECU Pin Function Diagrams may be found here if needed.
 
LH 2.4 came in 240 from 1989-1993, 740 (non-turbo) from 1989-1992, 700 Turbo from 1990-1992, 900 all from 1991-1995.
Exceptions: Some U.S. market 240 series with manual transmissions received LH 3.1. Some 700 series cars received Regina fuel injection.

Fuel Pump Function:
In the case of LH 2.4, the fuel injection ECU receives a coil/tach signal (at ECU Pin 1) when the engine is running.  The ECU then converts that signal to a ground (or control signal) and sends it out from ECU Pin 20, which goes to LH relay Pin 86/2.
The LH 2.4 ECU also sends battery power out through ECU Pin 9 and then into LH relay Pin 85. 

The ground from Pin 86/2 and power from Pin 85
completes the circuit to activate the fuel pump relay coil, closing the contacts and sending battery power from relay Pin 30 internally to relay Pin 87/2, which is the output for Fuel Pumps.

Main Fuel System Function: In the case of LH 2.4, the fuel injection ECU sends a ground (control signal) out  from ECU Pin 21 to LH relay Pin 86/1.  The Main Fuel System coil receives battery power from the relay Pin 30 circuit. These circuits activate the coil, closing the contacts and sending battery power from relay Pin 30 internally to relay Pin 87/1, which is the output for power to the MAF (AMM), Fuel Injectors, Cold Start Injector (if used), Idle Valve and for power to ECU Pin 9.
LH Relay Pin 30 gets battery power directly from the LH Fuse located on the 240 front left inner fender (if present).  In cars that don't have this fuse (1991 and later 240, 1989 and later 700 non-turbo, 1990 and later 700 Turbo, all 900 series), Pin 30 gets power from LH ECU pin 4.



    
 




Using Common Relays in place of the White Stribel Relay

Volvo PN 3523608
Millions of these white fuel relays were produced, so the thought of them running out or becoming hard to get seems unlikely, but genuine Stribel relays are more expensive than they used to be. 
Yes, there are cheap Chinese copies for less.  Are those reliable?  Don't know.

So if you ever find the need to use something else in place of that white Stribel Relay, here's a diagram below that will show the use of two common cube relays instead. These can be 4-pin or 5-pin relays, because only 4 pins are used.

Notes regarding DIODE: If you open the Stribel relay you'll see there's a diode soldered to the board on the fuel pump side. It is in-line between Pin 85 and the fuel pump coil. It's function appears to protect the fuel ECU from potential EMF flyback voltage from the coil. Adding a similar diode to the fuel pump circuit when creating a cube relay replacement seems to be prudent.
A suggested diode is IN4001 through IN4007, which can be found online for under $10 for a pack of 100. Keep in mind that the correct polarity shown below must be followed.
Further info may be found in the following forum discussion: https://www.turbobricks.com/forums/showthread.php?t=349135

 




How to Remove Terminals from Relay Plugs
  
Here we have a typical 6-poe fuel relay socket plug above used in many Volvos.
If you should need one of these plugs or the terminals that go in it, you can find those in my Harness Parts Page HERE.


This plug BELOW is NOT a 6-Pole Fuel Relay plug, but it'll work for this demonstration. The technique to remove terminals is the same. 
Notice the metal terminals inside the holes? Not all the holes always have terminals.

You'll need a tool for this part... a long sharp pick will do. A micro screwdriver can also be used.  If your tool is not small enough on the tip, a little grinding will fix it as I did on this pick. Even a stiff piece of piano wire can work for this step.
 

Now pay attention to the little openings at the top of the little rectangular holes.  That wide spot is where you need to insert your pick.  The idea is to insert the pick in about 3/8 inch (10 mm) or so and push down to flatten the locking tab on the terminal. That locking tab holds the terminal in the socket.  In the next photos, the locking tab will be easy to see.  

If your socket doesn't have a wider opening that you can see, just pay attention to the below pics to know which side of the terminal to insert the pick into to push on the tab.


In this photo you can see the terminal backing out of the hole after the locking tab was released. 


 Here's a good view of the locking tab on the crimp terminal.  After you depress and release the tab and pull the terminal out of the socket, you may find that your tool bent and flattened the tab a bit too much. If you will be re-inserting this terminal into a connector, the tab may need to be pushed back out so it still engages when re-inserted.  It needs to be sticking out like in this photo to work correctly.  If you accidentally break the tab off, you'll need to crimp on a new terminal.

And make sure the locking tab is on the correct side of the socket hole when re-inserting. As it gets inserted, you should hear a 'click' which tells you it has locked into place. Always make sure by giving the wire a little tug.

And always pay close attention when you plug sockets like this back in to see if any terminals get pushed back out. That can happen sometimes if the tab hasn't fully locked the terminal in place.





Jumping a Fuel Pump Relay
How to "JUMP" or bypass the fuel pump circuit from your Volvo 240 fuse panel:
The fastest method to make the main fuel pump run (bypassing the Fuel Pump Relay) is by jumping two circuits at the fuse panel.
The KEY DOES NOT need to be 'ON' for this to work.
You can make a jumper from a piece of wire with stripped ends or even a straightened paperclip. Jumping the circuits on the
RIGHT side of the fuses will offer the best results. Either side will work, but the right side bypasses the fuse (in case that fuse is blown or corroded). 
For a 1979-84 240, jump fuse #5 to #7.
For a 1985-93 240, jump fuse #4 to #6.
S e e   b e l o w   d i a g r a m s



For a 1979-84 240, jump fuse circuit #5 to #7.
<<<
Here's a typical (1984) fuse panel diagram.  Fuse 7 gets battery power directly (unswitched).

For a 1985-93 240, jump fuse circuit  #4 to #6.
<<<
Here's a typical (1986) fuse panel diagram.  Fuse 6 gets battery power directly (unswitched).

<<< CUSTOMER SUBMITTED TIP:  [Provided by Thomas Schofield]  "I was left stranded today by one of my 240s, and was trying your methods to see if it was the relay that had gone out (it was). For whatever reason jumping the socket pins that the relay plugs into didn't give me any results, but bridging the 4th to 6th fuses did (it's an 89).
        So, I had to figure out the best way to get that paper clip to stay in there. Turns out you can put the end of the paper clip through the hole on the end of the fuse terminal and still get the fuse to sit properly/contacted. I did that on both terminals and away I went!  Held like a charm, and easy to recreate in a pinch." 

If the main fuel pump under your car does NOT begin running when jumped (you should definitely hear it humming if you get close), you either have a faulty fuel pump or faulty wiring to the pump (bad wiring is fairly common under an old 240 near the pump).  This test of course assumes your battery is good.
If one of the fuses at those circuits blows during this test, the pump circuit power wiring is shorting to ground somewhere between the fuse panel and the pump.

Also see http://cleanflametrap.com/transferPump.htm for more info.



GETTING YOUR 240 HOME WITH A
FUEL PUMP RELAY FAILURE

If you find that the above jump test makes your fuel pump run and you don't have a spare relay with you (or if your spare doesn't work either), here's a trick that will get you home.


The simple trick of course is to keep a jump wire (or paper clip) in place while driving.  If you can manage to do that, your pump will run continuously and you can drive the car without any adverse affect. This won't hurt anything it as long as you have fuel in the tank. 
Keep in mind that when you turn off the car, your fuel pump will continue running until you disconnect the jumper. 


JUMPING A MAIN FUEL PUMP FROM THE
240 Fuel Pump RELAY PLUG
 Trying to securely mount a jumper wire (or paperclip) to the fuse panel so it won't fall off can be difficult. There is another way that I find much better.
1977-78 240:
Step 1.  Find your fuel pump relay and unplug it. 
Step 2.  Look at the plug and the wire colors going into it. There will be a RED wire going into one of the terminal inserts.  That is the power from the battery. 
Also find the YELLOW wire.  This wire goes to the fuel pumps. 
Step 3. Jump or connect the RED WIRE to the YELLOW WIRE in this plug.  This should instantly power the pumps ON.

1979 240 and Later:
Step 1.  Find your fuel pump relay and unplug it. 
Step 2.  Look at the plug and the wire colors going into it. There will be a RED wire going into one of the terminal inserts.  That is the power from the battery. 
Also find the YELLOW/RED wire(s) (there may be TWO of this color wire going into ONE terminal).  These wires go to the fuel pumps. 
Step 3. Jump or connect the RED WIRE to the YELLOW/RED WIRE in this plug.  This should instantly power the pumps ON.

<<< Here's a simple tool you can make yourself and throw in your glove box. I have one in mine.  It's at simple jumper made with two easy to find .250 inch (6.3 mm) MALE crimp terminals and a piece of wire (14 gauge or larger preferred). These male terminals will plug right into the relay plug slots after the relay is unplugged. It might be a long while before you use it, so put a tag on there to remind yourself that it should jump the RED to the YELLOW/RED wire (or RED to YELLOW wire for pre-1979 240) to provide power to the pumps. 

If you are experiencing any mysterious electrical issues, here is a really good discussion thread on diagnosing a problematic late model 240 fuel pump circuit that was eventually solved:
http://forums.turbobricks.com/showthread.php?t=287210






Adding a Secondary Relay to take the High Load off your 240 Fuel Pump Relay
This is not for everyone, but it seemed to help for me for many years.
  <<< The fuel pump relay in your 240 takes a lot of abuse and it's expected to run your fuel pumps for years and years without fail.  They do fail, but usually not because they wear out. Most fail because of unwanted heat after years of use.   They often run hot because; 1. They handle a heavy load. 2. The heat causes their plug connections to develop higher resistance, which then causes more heat, which then makes a failure begin like the melted terminal in this photo. 

Below I have outlined how I added a standard inexpensive 4-pin cube relay (or 5-pin will work too) to handle the pump load, giving the original expensive fuel pump relay a much welcomed rest.  The new added relay can be any standard 4 or 5 pin type relay with a load rating of 15 amps or higher.



<<< Here's a pic of what that heat can do to the relay plug.  This is extreme. Most of the time the melt damage to the plug is minor, but it can get bad.

But even if you do NOT feel this mod is right for your car, please read the info BELOW on using Anti-Corrosize Zinc Paste on your electrical connections. I strongly believe this paste would have prevented the damage in these photos.



What this extra relay mod does is take the heavy load off of the expensive Volvo relay and puts it on the inexpensive standard relay.  This allows the Volvo relay to be used as a low current switch to activate the standard relay, which will handle the load instead.  
   
The new extra standard relay is triggered by pin 87 from the original fuel pump relay and receives its main battery power from pin 30 of the original relay circuit. 
As an option, you may instead run a dedicated battery wire to pin 30 on the new relay. I suggest 12 gauge wire. This should provide a bit more voltage to your pumps.  If you do this, then the wire should always contain a fuse between the battery and relay.
K-Jetronic (Mechanical Injection) Relay Mod with Second Relay
Volvo PN 3523639. Green in color.
Fits 240 DL, GL 1978-82 with K-Jetronic Fuel Injection,
240 Turbo 1981-85 all years (K-Jetronic), 260 1978-82 (K-Jetronic), 760 V6 only 1983-86 (K-Jetronic).




LH-Jetronic (EFI) Relay Mod with Second Relay
3523608 Relay Fuel Pump/Injection. White in color.
GENUINE Volvo was made by STRIBEL.
Same as previous Volvo PN 1347603.
Fits 240 DL/GL 85-93 all (LH-Jetronic 2.2 and 2.4).
740 85-92 all turbo and non-turbo.
760 87 6-cyl.
780 87-91 all (4 cyl turbo and 6 cyl).
940 non-turbo 91-93.
940 Turbo 91-95 (except for 1991-93 940 SE).



INERTIA SWITCH
Beginning in the late 1980s a number of vehicle manufacturers began using an inertia switch as a safety device to shut off the fuel pumps in case of an accident. This type of switch pictured below is a Ford type, which uses a magnet to keep the switch connected.  A sudden shock from any direction will disengage it. The switch may then easily be reset by pressing the red button.
A switch like this with a wire connector pigtail can be found used in a salvage yard or on-line.

An inertia switch may be wired in a NORMALLY CLOSED configuration to power a fuel pump or fuel pump relay.  Some manufacturers have used similar switches in a normally open configuration to activate passenger safety devices in a collision, typically to pre-tension seat belts or to activate air-bags.

This Ford switch below can be used as a normally closed or normally open switch. If you were to use something like this in an old Volvo, be sure to mount it to a solid place on the body, preferably in a convenient place that you can access easily if you need to reset it.




ANTI-CORROSIVE ZINC PASTE
If we can just just keep our electrical connections clean and tight, almost all of the electrical issues would be gone forever.  That would be nice, right?

I have owned a number of Volvos over the last 30 years and my current 240 is way over 30 years old. It almost never has electrical problems. Nothing like the endless numbers of other 240s out there that I hear about so often. What's the difference you ask?  The difference is that my 240 has been always garaged all of its life.  Why is that important?  Because leaving any car out in the open elements for years and years slowly introduces corrosion to grounds and power connections until things begin to go wrong. 
So if you own one of those cars that has been outside forever, it's not too late. You can still clean as many grounds and electrical connections as possible. 
And while you're at it,
I recommend that you smear a little anti-corrosive zinc paste on those connections. 
Many people in the Volvo community gravitate toward
Ox-Gard, which does a similar job.  

The below information was contributed by Ron Kwas and should come in very handy to old Volvo owners:
Anti-Corrosive Zinc Paste (a generic name for zinc dust contained in a grease) was originally developed for and later required by electrical codes for use on alumunum to copper electrical connections (or other dissimilar metal connections).  No, it's not the same as Dielectric Grease, which is often incorrectly recommended. Dielectric Grease can offer some protection in the form of encapsulation from moisture, but it also carries with it the potential disadvantage of locking in moisture or corrosion which may have already begun.  Anti-Corrosive Zinc Paste (or ACZP) is the next evolution of the encapsulation principle, because zinc (the lowest on the Galvanic nobility chart) neutralizes corrosion on a micro-scale to truly protect connections on a long-term basis during the encapsulation, INCLUDING an added protection from corrosion which may otherwise begin to form in that connection. 

Ron uses and recommends Penetrox A (by Burndy).  Many Volvo fans are familiar with Ox-Gard, which is a similar zinc compound. Ron and I are huge advocates of treating ALL electrical connections on our cars (except of course High Voltage Ignition connections) with a suitable version of this material. 
You can learn more about this stuff at Ron's page here: 
http://www.sw-em.com/anti_corrosive_paste.htm 


Upgrade the In-Tank Fuel Pump in your 240 with a Larger 740 Turbo Pump
The Bosch in-tank fuel pump found in your 240 Turbo will be the same pump used in all 240/260 models from 1976 to 1984.  It's very small and while it will provide adequate fuel to the main pump for a non-turbo Volvo, it has been considered by many to be too small for a turbo motor with any increased engine performance.  The Volvo part number for the original 240 in-tank pump up to 1984 is 1276330.  In 1985, that part number changed to 3507436, which was used through 1993. 

The used 740 Turbo pump I used for this conversion, which was used in 1986 and later 700 and 900 Turbo models (and 960), is PN 3517845
I got mine from a salvage yard.

This pump retails new for between $150 and $200.  It is also widely available in salvage yards for a lot less, although you should be cautious, because some pumps found in salvage yards may be dead.
I chose to install a used pump from a salvaged Volvo due to cost.
A good tool to bring to a salvage yard to test electrical parts like this is a drill battery. 
  If you need to test a pump, do it very briefly... only for a second.  These pumps are not designed to run dry and it can damage them quickly.


Here are a couple videos that might help.
https://www.youtube.com/watch?v=F7BqPr3X0AE


https://www.youtube.com/watch?v=JTvwv5-5hEM&t=705s



G E T T I N G   S T A R T E D
The photos shown BELOW are from a 240 SEDAN trunk. 
The 240 wagon will be a little extra work getting to the top of the fuel tank, but otherwise it's the same under there.
There is a connector and ground ring for the pump and fuel lever sender under that plastic cover near my screwdriver. And a photo of that further down

Begin by removing the access cover plate above the tank.
The two hoses shown here are the main feed line going to the main pump and the return line from the engine. 
I have also included a photo BELOW showing these two fuel lines under the car.


MAIN PUMP Feed Line: The original main fuel hose from the tank to the main pump was a cloth braided type and it's normally secured with hose clamps on the tank exit assembly at the top and also at the main fuel pump under the car. When this type of hose gets old and rotten, it will usually slowly begin to weep fuel. When weeping, it may begin so slowly that it only gets the outer cloth braid wet.  If you are noticing a fuel smell shortly after parking the car or if you see any fuel dripping under this hose, check this hose to see if fuel is weeping through.  Replace it if it's questionable, since it will only get worse with age. 

The original main pump hose size is 12 mm ID.  About 4 feet is needed if you need to order.  12 mm hose is common in Europe, but not so common in the USA.  7/16 inch ID fuel hose is a close substitute if necessary (be sure to choose high-pressure fuel injection hose), however even 7/16 inch ID can be hard to find in auto parts stores in the USA.  Some people have used 3/8 inch hose, but I think it's too small and will be difficult to stretch onto the fittings.   Both 12mm and 7/16 inch fuel line are pretty easy to find on-line.

Return Line:  This line transitions from a metal line under the car to a flexible rigid plastic line (covered with a rubber sheath) that goes up to the top of the tank.  This line will rarely ever need to be replaced unless you damage it in this procedure, but as you will discover if you do this type of work, it's very hard to manipulate this stiff line when removing the sender and pump assembly from the tank access hole. It does not disconnect from the pump assembly (unless you cut it off).  The procedure to disconnect this hose is shown further below. It involves disconnecting the in-line union seen in this photo, then wrestling the hose upward as you remove the pump and sender assembly from the tank.

The procedure below will show removing this WITHOUT cutting the return hose.
But after doing this job a few times and finding how much it sucked, I now choose to cut it off at the top of the tank.  So it's an option you can use if needed. When the hard plastic line is cut off of the end fittings on both ends, you'll see that the end fittings are just ordinary brass barbed nipple fittings and normal fuel line can then be secured on them with hose clamps.  The size hose for this return line should be 8 mm ID (or 5/16 inch ID will work too).  

 

Main Feed Line Cutting (optional):
In this instance I was replacing the main fuel pump hose because it was old and beginning to weep.  After removing the hose clamp, cutting it off at the fitting was the easiest way to remove it in my opinion, since it was stiff and hard to slip off.  


I like having the right tool for a job. 
iPd sells this tool for turning the top retaining ring on the pump assembly to release it from the top of the tank. 
If you don't have one, you can try using two large screwdrivers crossed over each other, or setting a large set of Channels Lock pliers in there and turning, or the hammer and chisel method to tap the ring until it rotates. 
 

To remove the retaining ring, it will need to turn about 1/8 turn to the left, counter-clockwise.

Before you can try lifting the pump assembly up and out of the tank, you must first disconnect the return line union.  This is done under the car.  It's a simple flair fitting. 
Use two open end wrenches (usually one 14 mm and one 15 mm).
 

Then you can slowly work the return hose Up and OUT toward the pump assembly.  I found that this hose needs to come up and out first, then you can gently lift out the pump assembly. 

When you do this, you will know why I chose to cut off and toss out the original plastic return hose and why I used a normal fuel injection hose with clamps for this hose instead.
 

Here is the old pump assembly out of the tank.  It will be a good idea to get a new pump filter sock for your new pump. 
 

You can see the size difference between the original 240 pump and the 740 Turbo pump. 
 

If you need to remove the pump and fuel level sender assembly from the trunk area to work on it elsewhere, pull up that plastic cover to the left and you'll find a connection plug and a ground ring there that you can disconnect.
WIRE COLORS ARE LISTED BELOW.
Note that the brown wire is the pump ground, but it does not go directly to the pump. It grounds to the pump/sender holder. And the pump then also grounds to the holder.

   

Remove the ring terminal from the old pump.  That nut will probably be 6 mm (or maybe 5 mm).
Release the orange plastic band holding the pump. 
Remove the hose clamps and the rubber fuel hose and the old pump from the metal tube.
 

Since the 740 Turbo pump is LONGER than the original pump, the metal feed tube needs to be cut down.  You'll need to trim about 1.5 inches.  Measure it yourself to be sure. 
Keep in mind that the BOTTOM of the new pump needs to be at the same vertical height as the old pump, so the sock filter will be at the bottom of your tank. 
If you cut off a little too much of the metal tube, it's OK. You can always just put a slightly longer rubber hose on. This is not difficult.
 

CAUTION: If you find a rubber "accordian" style hose that looks like this original one, DO NOT reuse it. 
That is a weak hose that commonly deteriorates with age. It will eventually rupture and cause problems.
 

Here's the new 740 pump in place. 
When you re-insert the pump assembly back into the tank, go slowly. Be careful to avoid snagging the wires. 
 
If you know of any helpful hints not mentioned here, please write me. 
CONTACT 

Thanks,  Dave

MORE USEFUL LINKS ON THIS SUBJECT
http://cleanflametrap.com/transferPump.htm

 

Fuel Pump Check Valve
The Volvo 240 uses a fuel pump check valve in the main fuel pump to maintain pressure beyond the pump when power is off, so the fuel in the line doesn't drain back into the tank.  Sometimes a fuel injected 240 will begins to have a problem with fuel pressure. Specifically it may result in longer cranking to start the car.  The most common diagnosis for this is a failing FUEL PRESSURE REGULATOR.  Sometimes the problem actually IS a bad fuel pressure regulator, but NOT ALWAYS. Keep in mind that there's also a CHECK VALVE in the main pump which can fail. Failure can be from debris or foreign material lodging in the valve or sometimes the valve parts can disintegrate from long use.

The check valve is a separate part which can be replaced.
Volvo PN 1306990: 240 K-Jet B21F, Turbo B21FT.
Volvo PN 1326899: 240 non-turbo LH B23F, B230F.
 
There's a video below on this replacement.
 

Replacing a Fuel Pump Check Valve
https://www.youtube.com/watch?v=qIW3VgovsYM

Here are some useful diagrams for early K-Jetronic 240 fuel pump check valves.
(PDF, click to open)





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