avhart

Hi and good morning to all,

My problem today concerns (as usual) my fuel pump. It was working just fine until I took it out this morning to go to the grocery when it shut down about 100 yards from my garage for, as it turned out, lack of gas. So I went ahead and put a 12v jumper to the FP tap in the engine diagnostic connector and she started right up and took me back home. When I remove the jumper it still won't start.

Do you think that's a prob with the pump itself or could it be the fuel pump control ECU (89570-50010 - in the trunk)?

paulo57509

If the pump runs when jumped directly thru the Diag Connector, the pump works. Cross off a bad fuel pump off your list.

Is the fuel pump not running a intermittent problem? You might want to look at the fuel pump relay? If you have a wiring diagram, you might try jumper the socket terminals that feed the fuel pump (essentially bypassing the relay). I don't know how expensive the relay is, you may just want to go ahead and replace it.

avhart

Hey Paulo, thanks for the reply. In my case the car does not have a fuel pump relay. It has instead a fuel pump control ECU (89570-50010) so I'm wondering if that is my problem.

paulo57509

If you can find a controller, this might be the easiest route.

Hopefully, someone will come along with a fueling wiring diagram or some further diag procedure.

Yamae

First of all, I'd check the voltage of the pin 5 line (G) of the fuel pump ECU (lower left corner). This line should be between 5-8V when fuel pump ECU is driving the pump with lower speed. When the fuel pump ECU is dead or not working right, the voltage is lower than 5V. Sometimes semi-short circuited fuel pump causes too low voltage though.

avhart

Thank you so much for that detailed explanation, Yamae. I will check that voltage later today. On a related matter, what is your opinion if I were to just bypass the module completely and run the pump at 12v continuously.

Yamae

To run the pump at 12V continuously will reduce the lifespan of the motor due to the extra heat. But I don't know how long the motor actually lasts. I once have tried to bypass the fuel pump resistor and applied the 12V DC to the motor directly. It worked well but it was just the confirmation and I stopped to bypass it within a day.

avhart

Got it, thanks. I will disregard that option for now. Unfortunately I have the feeling that the pump is once again the problem and not the control module but I will do my due diligence. These pumps keep failing on me continuously...

paulo57509

Could it be possible for a bad control module being the cause for the fuel pump failures.

avhart

Well not too long ago I opened up the module and saw like a small part of the PCB had a burn so maybe that's really it.