Can’t get power to my fuel pump Volvo 140s

[Kaleo Ake]

Hello, I’ve been struggling for a while chasing down this issue with getting power to my pump. Car is a 1972 142s. So car was running before just about a month ago and then it wouldn’t start again. I’ve done a bit of diagnosing and found that my fuel pump relay was getting no power from all terminals in the relay. The main fuel relay does get power though. I’ve sent 12v straight from the fuel pump wire to pump and I could hear the pump and car would fire then die. Ive inspected the fuel pump wire all the way down to the pump and everything looks good. I’ve replaced both relays and that didn’t work. I knew I had an issue probably from the battery to the fuel pump relay. I’ve looked into the distribution block and cleaned all the connections. I’ve also checked the little fuse junction on the inner fender of the drivers side and the connections there look good. All fuses inside the car are good as well. Anyone know about these early fuel injection cars? Any pointers would be appreciated thanks!

 

[JohnMc]

Is the ECU powering on? Turn the key on, obviously the fuel pump won't prime, but you can tell if the ECU is live by listening carefully (maybe up by the engine) when you open the throttle. The throttle switch will set of injector firings (the injectors are wired in pairs) as the throttle opens, it's how it does accel enrichment. If it's not clicking when you do that, the whole FI system may not be getting power.

In this time frame there was a separate power wire leading to the positive terminal on the battery. I forget if there's a separate fuse or not (probably is). I once spent an embarrassing amount of time diagnosing the fuel pump on my 71 1800E when that wire got bumped somehow and pulled out of the terminal.

 

[Kaleo Ake]

Is the ECU powering on? Turn the key on, obviously the fuel pump won't prime, but you can tell if the ECU is live by listening carefully (maybe up by the engine) when you open the throttle. The throttle switch will set of injector firings (the injectors are wired in pairs) as the throttle opens, it's how it does accel enrichment. If it's not clicking when you do that, the whole FI system may not be getting power.

In this time frame there was a separate power wire leading to the positive terminal on the battery. I forget if there's a separate fuse or not (probably is). I once spent an embarrassing amount of time diagnosing the fuel pump on my 71 1800E when that wire got bumped somehow and pulled out of the terminal.

I’ll check on this today. This could be very likely and my injector wires are starting to disintegrate so I’ll try to fix that as well.

 

[bgpzfm142]

Connections to your fuel pump relay should be -
- white wire, going between ECU terminal [19] and relay terminal [85] (the coil), so you should see 12V.
- white wire, going between terminal [87] of the main FI relay, and relay terminal [86]. That terminal [87] of the main FI relay should also have wires hooked back to ECU terminals [16] and [24]. This is the 12v supply to the fuel pump relay's coil, from the main FI relay.
- yellow wire, going from pump relay [87] and off to the fuel pump, to supply 12V to the pump.
- yellow wire, from terminal 30/51 of the FP relay to a fuse. This supplies 12V power to the fuel pump when the relay operates.

Connections to your main FI relay should be:
- yellow wire, from terminal [86] of the MFI relay, to the 'ignition on' 12V supply at the fuse box. this supplies 12V to the relay coil via a diode.
- white wire, from terminal [85] of the MFI relay, to ground.
- red wire, from terminal [30] of the MFI relay, directly back to the alt or battery for 12V supply.
- white wire(s), from terminal [87] of the MFI back to the fuel pump relay terminal [86], (to repeat myself) That terminal [87] of the main FI relay should also have wires hooked back to ECU terminals [16] and [24]. This is the 12v supply to the fuel pump relay's coil, from the main FI relay.

Good luck!

 

[Kaleo Ake]

Connections to your fuel pump relay should be -
- white wire, going between ECU terminal [19] and relay terminal [85] (the coil), so you should see 12V.
- white wire, going between terminal [87] of the main FI relay, and relay terminal [86]. That terminal [87] of the main FI relay should also have wires hooked back to ECU terminals [16] and [24]. This is the 12v supply to the fuel pump relay's coil, from the main FI relay.
- yellow wire, going from pump relay [87] and off to the fuel pump, to supply 12V to the pump.
- yellow wire, from terminal 30/51 of the FP relay to a fuse. This supplies 12V power to the fuel pump when the relay operates.

Connections to your main FI relay should be:
- yellow wire, from terminal [86] of the MFI relay, to the 'ignition on' 12V supply at the fuse box. this supplies 12V to the relay coil via a diode.
- white wire, from terminal [85] of the MFI relay, to ground.
- red wire, from terminal [30] of the MFI relay, directly back to the alt or battery for 12V supply.
- white wire(s), from terminal [87] of the MFI back to the fuel pump relay terminal [86], (to repeat myself) That terminal [87] of the main FI relay should also have wires hooked back to ECU terminals [16] and [24]. This is the 12v supply to the fuel pump relay's coil, from the main FI relay.

Good luck!

Thank you so much!

 

[Kaleo Ake]

Is the ECU powering on? Turn the key on, obviously the fuel pump won't prime, but you can tell if the ECU is live by listening carefully (maybe up by the engine) when you open the throttle. The throttle switch will set of injector firings (the injectors are wired in pairs) as the throttle opens, it's how it does accel enrichment. If it's not clicking when you do that, the whole FI system may not be getting power.

In this time frame there was a separate power wire leading to the positive terminal on the battery. I forget if there's a separate fuse or not (probably is). I once spent an embarrassing amount of time diagnosing the fuel pump on my 71 1800E when that wire got bumped somehow and pulled out of the terminal.

Is the ECU powering on? Turn the key on, obviously the fuel pump won't prime, but you can tell if the ECU is live by listening carefully (maybe up by the engine) when you open the throttle. The throttle switch will set of injector firings (the injectors are wired in pairs) as the throttle opens, it's how it does accel enrichment. If it's not clicking when you do that, the whole FI system may not be getting power.

In this time frame there was a separate power wire leading to the positive terminal on the battery. I forget if there's a separate fuse or not (probably is). I once spent an embarrassing amount of time diagnosing the fuel pump on my 71 1800E when that wire got bumped somehow and pulled out of the terminal.

With the key in the on position I can’t hear any injectors or any other sounds when I open the throttle. My fl relay is getting power though I can hear and feel the solenoid. Is my fl system getting no power at all?

 

[bgpzfm142]

Is my fl system getting no power at all?

Check out this document, which may help with your troubleshooting.

Oz Volvo Technical Archive

ozvolvo.org

 

[hiperfauto]

Check the wires to the trigger contact points at the distributor. I knew that broken or disconnected wires could prevent the injectors from clicking when opening the throttle but was unaware that it could prevent the pump from running.

 

[Kaleo Ake]

Check the wires to the trigger contact points at the distributor. I knew that broken or disconnected wires could prevent the injectors from clicking when opening the throttle but was unaware that it could prevent the pump from running.
View attachment 33216

This sounds a lotttt like the problem I’m having. The car was running rough before, probably only off a pair of cylinders, and after trying to mess with the dizzy those contact points must’ve gotten more messed up ending with the pump not working. When I checked them just now the wires were being pulled out of the little plastic connector that plugs into the dizzy making a weak connection so I fixed that. Battery’s dead but I pray this is the problem! Sounds just like it.

 

[hiperfauto]

I have repair parts for that connector if you need them.