Fuel pump?

[Fred D.]

1994 Q45 130,000, pretty well maintaned.I know when my fuel pump starts to humm its gone bad and is causes extra electric strain on FPCU, & Im in the process of replacing it(F.P.$). My question is it possible for FPCU to cause the engine light to come on, and go off? I have checked ECU for codes and it only gave code 55 all fine. Thanks for assistance.

[elwesso]

the short answer is NO.. I wonder whats causing the CEL, so it comes on and off on occasion? It should still store codes!

[Fred D.]

Thats what I thought, that it would store the code. It also feels under powered when the light is on (check engine), maybe FP or FPCU. The light only stays on fo five minutes then turnes off, some days it doesnt come on at all with WOT run's. If the fuel pump is straining the FPCU could the solder be melting and causeing the light to come on and go off, doesnt seem to be consistant with the way I drive WOT alot. Thanks for any help.

[Q45tech]

The ecu has no simple or complex method to determine fuel pressure so no code nor will a low fuel pressure illuminate the check engine light.

In closed loop cruise the ecu has a 30% range to increase steady speed fuel injection time but it assumes something else is going on.

Evaluate the block learn [adaptive learn] to see if injector duty cycle is as preprogrammed.......................easiler to just measure the fuel pressure at idle and under full load.

[Fred D.]

(Q45tech) your stating,A bad or failing FP and FPCM, will not cause check engine light to illuminate. I see only FPC & FPS is on the code list, # 22, & # 42, no fuel pump though. I will check injectors, but I want to know why no codes, with a illuminated check engine light are'nt consistant with each other.Thanks.

[goody90q45]

The first time I pulled the code off the ECU I was following the instructions in the FSM and mistakedly rotated the ECU screw twice which erased the codes and gave me the 55 code.

I would think the codes should be stored on the ECU even if they've cleared. The FSM instructoins were a bit confusing to me as a newb so I'm just bringing this up to make sure you didn't make the same mistake as me.

[Fred D.]

I may have turned it twice, I cant remember-it was a long day.This is why I like NICO , every one seem's to have a diffrent perspective. I really apprciate the help, I will check again tommoro and look for codes.