Diagnosis help (fuel pump/relay, FPCM etc..)

[Q45dude]

94 Q45 with 160k miles. I need to find out what needs to be replaced. Please see the history of events:

Since its time for my registration and smog check I decided to spray clean the intakes/plenum through the throttle body. took out and sprayed the EGR valve which contained alot of black stuff in it (carbon build up). Also spray cleaned the MAF and was in a hurry and messed up the maf.
so I start the car afterwards (thats when I found out the maf has been F----d up) cause the car was running like a diesel truck and wobbling and stuff.

I drove the car to work and back next day (not too far). got a MAF and changed it and noticed a huge difference. no smoke now but the car still was not like it used to be.
Started turning off at stops and at idle.

now the car won't start and noticed when i turn the switch on I don't hear the pump when you first hear it upon turn of the switch.

I have an extra FPCM, so I switched it thinking maybe its that but didn't fix the problem.

I don't whether the fuel pump (replaced brand new about a year ago and was Genuine Infinit pump) has fried driving under that condition.
Or is it the fuel pump relay?

Sorry about the long history. Any need would greatly be appreciated

[Lokim]

Try disconnecting the battery for at least half an hour to reset the adaptive memory.

If that doesn't help, open the fuel line after the filter and put the end in a jar or something. Turn the key on and see if the jar collects gas. If not, check at the pump for power upon turning the key on. If there is no power, check the relay and fuses.

If it does get gas, I'd bet the EGR is stuck open and that was causing the rough-run/idle-stall issue and may have fouled the plugs. If the EGR valve sticks open, the computer thinks the car is running lean, so it starts enriching the mixture to get the O2 sensor reading it wants. Pull the valve and see if it is stuck. Pull a couple spark plugs and check their condition. If no dice, get back to us.

[goody90q45]

Stalling? Check the MAF connector and make sure the pins fit tight, are corrosion free and are lubed with dielectric grease. The female pins should look like the middle one in the pic.



IIRC correctly the only purpose for the relay is to run the pump for 5 seconds when the key is turned to the ON position, without starting the engine. You should hear the FP run to prime the fuel system when the key is turned on and then shut off after 5 seconds. If so the relay is working.

If you suspect a bad FPCU try bypassing it. Run a jumper from the FPCU connector pin shown in the pic to a ground on the chassis. The only other thing I can think of is the fuel pump fuse got put back in the wrong spot. There should be an empty slot above the FP fuse.