No ground in fuel pump relay socket Volvo Penta 4.3 GXI

[teslasun]

Agree with funtimes about the corrosion at the female lead(s). Needs to be attended to before fully troubleshooting the issue.

Based on your information and the wiring diagram provided it appears the ground for both relays is the same and tied into the harness ground circuit, not controlled electronically/anything special. The wiring diagram doesn't exactly match wire color(s) you mention however the system in question is not complex. It has constant 12 volts + and constant ground. The relay is energized by the ecm to make contact between the constant 12 volt + and the + lead for the fuel cell assy.

When you say by adding/jumpering a ground the relay works and provides + voltage to the fuel cell it appears you have found the issue, just need to clean/solidify the ground and repair/replace the faulty fuel pump cell/assy

Thank you. I hope to publish here a short video of the engine running once the new fuel pump is installed

 

[bruceb58]

Ripjmk is correct...the ECM creates the ground path. You will not be able to measure it at the connector.

 

[dubs283]

You have throttle body fuel injection controlled by a MEFI engine control unit. The fuel pump relay is actuated by the MEFI providing a path to ground when it deems it is ok to do so. You need the VP EFI diagnostics manual (VPA 7742218 03-2003) to guide you to a solution to your problem.
The fuel pumps should turn on for approximately 2 seconds when the ignition key is first turned on to build pressure in the system and then shut down until the engine control unit senses the engine running ok when it turns them on again.
Do you hear them turn on for a brief period when you turn the ignition on but not try to start ?

This info is standard first go to troubleshooting, I agree with everything in this post save for one (maybe two) factors.

OP had not posted any Volvo serial/model/product numbers and the wiring diagram posted may or may not be engine specific for this issue. Yes, there are many MEFI controllers that provide ground for various components but without actual verification we can only base our opinions on info provided

 

[teslasun]

Ripjmk is correct...the ECM creates the ground path. You will not be able to measure it at the connector.

Thank you all of you guys. Once the pump is available I'll try to test the original configuration of the switch once again. The problem to me is that in the first slot of the fuel pump switch power is always on, no matter the ignition key is on or off. But perhaps it is as it should be and MEFI solves this issue, I don't know. I'll browse the manual as well, as suggested https://vdocuments.net/10322862-download-volvo-penta-efi-diagnostic-manual.html

 

[ripjmk]

This info is standard first go to troubleshooting, I agree with everything in this post save for one (maybe two) factors.

OP had not posted any Volvo serial/model/product numbers and the wiring diagram posted may or may not be engine specific for this issue. Yes, there are many MEFI controllers that provide ground for various components but without actual verification we can only base our opinions on info provided

OP posted picture of engine showing cover label "4.3.GXI" and clearly that is a MEFI ECU attached to the STB riser. The VP EFI diagnostics manual states it covers this model. The manual clearly indicates all I said in my post is true!

 

[teslasun]

Unfortunately, still no luck... I've installed new high pressure fuel pump (it works), 2 new injectors (work), 2 new relays, checked all the fuses, the starter cranks, spark is present, fresh fuel. But engine doesn't want to start anyway, nothing. Should I call an exorcist?

 

[Lou C]

Is there any way to test the ECM itself?
I did hear of a place that tests & repairs these units.

 

[teslasun]

Is there any way to test the ECM itself?
I did hear of a place that tests & repairs these units.

Thanks Lou, I'll try to get it tested.

 

[89retta]

Have you checked to make sure the kill switch is properly attached? If it's not fully attached it will cut power off to the pump

 

[teslasun]

Have you checked to make sure the kill switch is properly attached? If it's not fully attached it will cut power off to the pump

Thanks for your suggestion. Yes, I know it happens sometimes but this boat has no kill switch... Perhaps it is one of the sensors, of throttle position or crancshaft, I don't know. Tomorrow I'll have more time to look into the problem again.