1996 Volvo penta 4.3 not getting power to fuel pump

[Colby dorris]

So I have been trouble shooting lately because I’m not getting power from the red and yellow wire that goes in to the fuel pump.I replaced the relays and fuel pump and made sure the alternator is working and it was im still not sure what’s causing it to get now power.Any advice or pointers thank you. 4.3GSPMDA (AQ) model

 

[alldodge]

I don't have a 4.3 GS wiring diagram but do have it for the GL and the 5.0 GI and GS. Neither show a Red/Yel wire feeding fuel pump but no biggy. They all show the ECM applies a ground to the FP relay to turn the pump ON.

Only the GL uses the ALT to keep power on the FP, but all EFI motors (TBI or MPI) the ECM applies a ground on the relay

Do you have power on pins 30 and 86 of the relay, and is the fuse good?

 

[Colby dorris]

I’m not sure if I have a fuse I don’t think I do,I think I just have diodes,and I’m almost I’m getting power to everything that the fuse connects but I’ll check.

 

[alldodge]

Are you carb or fuel injected?

 

[Colby dorris]

Are you carb or fuel injected?

Carb

 

[alldodge]

Being a carb then FP is powered thru ALT when running and Yel/Red when cranking. Both of the wires have a diode inline so one circuit does not back feed the other. Might just be the diode. Use a meter to check resistance on the diode scale if it has one.

Put leads on each side of diode and measure, then swap leads and measure. One way will read high resistance and the other low resistance. If you get infinite resistance then diode is open and will not pass power

This is a GL but note the diodes 23