Hi guys, was repalcing my O2 sensor(ECM was throwing O2 error code) on the weekend and reset the ECM afterwards by disconnecting the positive battery cable then connected it back after 10 minutes.. I turned the ignition key in the on position I noticed the check engine light was not illuminating...I tried to start the car and nothing...It cranks no problem but wont catch...did I kill the ECM??..looks like it ....checked the ECM fuse..its ok

I noticed no fuel pressure on my gauge when the engine was in the on position..Usually have pressure

Should have disconnected the negative when I was changing the sensor but didnt ....:doh

Any help would be great

 

Hi guys me again...I replaced the ECM with a new one and same thing!!...no check engine light and it doesnt start(will crank over)....Could it be the Ignition module is fried?? and the check engine light is cooked??.....what gives??

 

What year is the car and which FI type is it (TPI, TBI?).

At key on-engine off the fuel pump should run for 2 seconds. Listen for it, it may explain the lack of fuel pressure, which would explain the lack of starting.

The FP relay is driven by the ECM.

RBob.

 

Hi RBob My car is an 88 Iroc 5.7L TPI...Even if the FP relay is shot ..shouldnt the check engine light still come on???

It cranks no problem but wont start

 

Was looking in my Hayes manual and on the schematic diagram shows the battery connected to a Fuse & holder which then connects the ECM +12v and also goes to the Fule pump relay...It shows this Fuse and Holder in the front of the engine bay by the rad on the drivers side.....This could be the problem...Anyone know where I can find it???..I looked and cant find it...The fuses in the fuse panel in the car are ok...the Engine control fuse and the fuel pump are fine......

HELP!!!..this is ticking me off!!

 

Hi again, found the problem...It was the fuse for the fuel pump relay and ECM in the Engine compartment!!!!...She fires up no problem

 

That's good news. Was the fuse actually on the drivers side by the radiator? Reason I ask so I know and it is in this thread.

I know that GM also put them on the passenger side in a wire along the fender. If you don't know they are there, you'll never find it.

RBob.

 

Yeah, its on the passenger side on the fender close to the - ve battery cable you cant miss it...In my manual it was showing a 1987 model which is located on the drivers side along with the battery.... in 88 they switched the battery to the passengers side along with the fuse....Hopefully the store wont give me a hard time bringing back the new ECM ...going to install my factory ECM back tonight...

 

:thumbs up:

Thanks,

RBob.