my fuel pump recently quit on me, and at the same time, my check engine light stopped coming on, so im thinking its something with the ecm. i already searched, but can't find any threads telling how you go about testing the functionality of the ecm.

all of my underdash fuses are good. is there an underhood fuse, or one on the passenger side where the ecm is? which leads do i need to be checking for power?

 

There is a ECM fuse in the fuse box and it should say ECM on it?...in the tech articles theres a ECM diagram and in that.. there should be a power wire the one that comes from that ECM fuse to the ECM ,dont know if the 87 is different then an 86 but should be close?..as long as you have power there,and all your grounds and fusible links(at the starter etc.) are good then I would say the ECM is a good place to start.

 

is there a way i can test the ecm itself? things are expensive, i dont want to just start throwing money at the car.

 

Easiest method to test is to try it in another vehicle.

There is a good possibility there is a fuse under the hood. Many of the f-body's have one. If there, it is inline, heavy wire, comes off the battery and runs along the top of the passenger side fender. May also be up by the battery.

RBob.

 

wish i did, but i dont have another 5.7 tpi car sitting around to test it in. can i turn unplug the harness and turn the key to acc, test the harness pins for power, or is it bad to turn it on with the ecm unplugged?

 

No, the power is not to the ecm in acc. mode.
Unplug the canister plug and test for voltage w/key on.
Unplug the relay with the big orange wire and test for voltage there.
Assuming all the fuses have been checked you should have voltage at those connections.

 

what is the canister plug?

 

SWEEETT!!!! while looking for that orange wire, i pulled out a plug that looked to me before like it was just a connector, but actually it had a 20 amp fuse inside that was popped. thing fired right up. id almost forgotten how freakin evil that thing sounds, was music to my ears. thanks for trying to help my dumbass everyone, and no thanks to the shop that told me my fuel pump was done and they wanted 700 bucks.

 

I wonder why the fuse popped?

 

i dont know, but i replaced it, was fine in the driveway, i drove it a few blocks, got sideways (hey, its been a while since i've had the pleasure) and it popped on me again. obviously theres a power wire bumping a ground somewhere, but im not sure what all wires could pop that fuse. is that just one wire that leads from the battery to the ecm that i can trace the whole way? i really only know the basics of wiring, and its a mess under my hood.

 

ok now im looking at the wiring diagram in my service manual. its in section 6e3-a2-5 if anyone has a 1987 manual and wants to look it up.

i see the power lead off the battery, into the fuse holder, then it splits into 3, one goes and splits into 2, one for each ecm harness. another of the 2 goes to the fuel pump relay, and another goes and splits twice, one to the maf sensor burn off relay, and another to the maf sensor power relay.

could one of the grounds being loose cause current spikes to pop that fuse, or does it have to be an exposed wire someplace touching a ground? anything else it could possibly be? sorry for the noobish questions, but im still learning electrical diagnostics.

 

Bump -- Same problem with mine well not the popping on hard corning but mines popping 20amps to it takes about a days and a half and i mean a day and a hald where all day im driving the car like it should be driven and then all the sudden when i accelerate hard the fues poped again but i didnt do it for a day and a half of hard accelereating just after a white of doing it. Fuel pump going bad? Maybe pulling to many amps trying to keep working?