i am working on an 88 iroc, with a L98. automatic coupe. pretty decent, unscathed ole' car. i am in a pickle, and could sure use some expertise here.

a friend just recently purchased this car, someone has installed a fresh engine/trans. looks good. sounds good. runs good. no SES light. no codes (with the exception of one for a MAF circuit low, one time whilst i was scanning it, but havnt seen it sense after clearing it) i tidied up under the hood. verified all grounds i could come across. checked connections, connectors and so on.

with the KOEO if you hit the brake peddle or turn on the headlights or even the hazards or signals the fuel pump will complete a prime cycle.

that is correct... fuel pump, headlights.

other than that, car operates great.

i have disconnected, reconnected, tried with and without everything imaginable. literally. im figuring,that for some reason the ecm is getting a signal that it thinks is RPM and it is setting fuel pump cycle in motion, then when it sees it isnt running, it ends. everything is kosher between relay and ecm. even replaced fuel pump, maf, burnoff and so on relays just for giggles.

if i disconnect either/and/or the 4wire connector at the distributor, or either 2wire connectors at the coil the problem goes way.

if i remove all the bulbs in the car, the problem goes way.

i have added grounds temporarily here and there on these circuits in hopes of stumbling across the problem with no luck.

i guess more than anything after rackin' my brains all evening, then dismantling a perfectly good car, i just wanted to vent.

i think this evening i will try to isolate the problem by eliminating the lockup and braking circuits. sigh....

any thoughts, ideas, smart **** remarks, name calling and/or prayers are welcomed.

thanks-

 

I'm with ya buddy Wish someone would have helped ya 7 months ago...

PS:

https://www.thirdgen.org/forums/tech...mes-brake.html

 

In case your still on the forums or happen to get this message, please let me know. I'm having the exact same problem and seem to have tried everything you did and more! I've been at it for 2 months straight now!

I'll pray that you get this and help me! lol

 

Wow, this is an old thread! I just transplanted a Chevy TBI (sensors, ecm, etc. too) into a Jeep, and am having a similar problem.

If the key is off, car not running, I can turn on and off the lights.

If the key is on, car not running, Each time I turn on the headlights or running lights, the fuel pump performs a 1 second-ish prime.

Anyone figure this out yet?

 

sounds like they crossed the wire that supplys power on the relay with the headlight circuit somehow. I had just chased down wiring junk on my car and finally got it all back right. Some people shouldnt even work on cars. po had put cheapo alarm and bypasses on......but finally got it right. 1st id say eliminate vats as an issue, the starter interrupt circuit, then trace relay wires for proper operation.

 

The part that is confusing me is that the relay only gets a 1 second pulse of 12v when the lights are turned on. It is not simply an issue that when the lights are on, the pump is activated full-time.

The light switch I have is an old pull-type switch that has a first stop for the running lights, and a second stop, farther out, for the headlights. If I pull it out to the first stop, the running lights turn on and I get a 1 second prime. If I then pull it out to the second stop, the headlights also turn on, but I get another 1 second prime. Then, if I push the **** back in to the first stop (which would turn off the headlights and keep the running lights on) I get yet another prime!

I thought I needed to isolate the relay better, but I am taking power straight from the battery...

 

Read these two threads and it will explain to you exactly what I did to fix my/your problem.

https://www.thirdgen.org/forums/tech...mes-brake.html

http://www.justanswer.com/pontiac/58...eadlights.html

 

After reviewing those threads... I came to the conclusion that its way too much for you to read... let me just post the answers.

 

This is a post I posted on the Justanswer.com website when I finally fixed the problem:

Ok, Now I'm confused and a bit worried because I seemed to have fixed the priming problem but dont know how or why...

This is exactly what happened: (Remember the distributor was out of the engine)

I went ahead and removed the intake bolt and them moved the circle connectors for the grounds off to the side and separated them. I then tested the connectors individually and well just as I suspected, the ECM connector that has the two Black/White wires on it, had voltage....

So then I went over to the ECM and started testing the pins to see if any were getting voltage and what was going on at the ECM when the Black/White wires were no longer grounding the ECM.

Almost every single connection at the ECM had voltage.

So then I removed the 2 bulk connectors from the ECM and checked the voltage at the pins on the connectors. The only ones that had voltage were the ones that were supposed to have voltage which were 2 Orange wires and then the Pink/Black Ignition wire. Turning off the ignition would cause the Pink/Black wire to lose its voltage.

So I went ahead and put all of the fuses back in that I had previously removed the day before yesterday.

Now I went ahead and plugged the 2 connectors back in and then I checked if the ECM casing had voltage and it did! Although I knew it was going to have voltage since it wasn't grounded, just like the ECM builder had said, the voltage has no where to go but to the grounds. I also noticed that my SES light was on but it was very very dim.

So with my 12v test light probe and the Ignition ON, I would touch the ECM casing and it would turn on the test light, and every now and then it would even cause my fuel pump to prime, this was completely inconsistent because sometimes it would not prime and sometimes it would.

If I turned the ignition OFF then the SES engine light would still stay dimly lit until I touched the ECM case with the test light and then the SES light would turn off and my ECM would no longer be hot or turn on my test light.

I then got a wire and a battery clamp and shoved one end of the wire into my frame and then used the clamp to clamp the other end on my ECM case to ground the ECM case.

By doing this, everything started working again and my SES light was now brightly lit just as it should be.

So, I though this was really weird but anyways. I decided to throw my distributor back in and see how and when the fuel pump would prime with the ECM casing grounded to the frame rather than through the circle connector at the rear intake bolt.


I put the distributor half ways in and then connected the dist. connectors to the ICM. So then I tested the headlights and yes the pump still primed...

So I though maybe the distributor isnt grounded good enough since it was only half ways in so I went ahead and put the distributor all the way in and then it finally snapped in and went all the way down.

Went over and tested the headlights, THE PUMP DID NOT PRIME. So I was pretty confused and didnt believe it so I kept trying and I could not get it to prime.

So I then put on the dist. clamp and bolted it down. The pump still did not prime with the lights, so then I grabbed the ground strap and put the ground strap circle connector onto the dist. clamp bolt, and then tested the lights, the pump primed! So I removed that ground and then I could not get it to prime, so I put it back on and then this time I still could not get it to prime! lol

So this was really confusing! but anyways....

I removed the ground from the ECM casing and then connected the rear intake bolt grounds to the distributor clamp to see if it had been the ECM case ground that was causing the problem to go away and No, the lights still did not prime the pump!

So I put all of the fuses back in and connected the headlight module and connected the rear lights harness and everything else!

I then used the intake bolt to bolt the grounds that had been on the intake bolt to the rear of the cylinder head (Their original location) I connected the ground strap and everything else. Nothing primed the pump anymore no matter what I did.

I dont know if this is either good or bad... but I may have just fixed the problem. I started to put my car back together but ran out of electrical tape and well everytime I connect something back I go test the lights to make sure they do not prime the pump, I've tested the hazards, headlights, brakes, and turn signals and nothing will prime the pump any more... Well of course turning the key off and then back on will prime it but none of the lights prime the pump.

So what do you think?

Also noticed that the distributor gets a bit warm as well as the coil. Going to go back out there and check on it and the lights right now. So let me know what you think the problem was... I'm thinking it may have been that the distributor never went in right but that doesn't really make sense because I dont see how that could happen?

AND for all I know, I might still have the original stalling issue... but I cant turn on my engine at 2 in the morning to see if thats still going on but I'm thinking that these two issues were related.

So I am going to report back in a few minutes after I come back in and double check everything. I really dont like how I fixed it because I dont really know if I did or not. Just cant seem to get the lights to prime the pump anymore.



Read more: Brake Lights..brake pedal..Hazard lights -Turn Signals..Headlights - JustAnswer http://www.justanswer.com/pontiac/58...#ixzz2HA63Atiw

 

This is an email thread with me and BobR:

 

Thanks Napster! I will check out the ground situation and check back in a few days!

 

It a nutshell, the problem was simply a bad ECM ground. Seems to be your problem as well. Make sure that the ECM grounds are not grounded to anything aluminum or anything that doesn't look like a REALLY good ground. Best place is the frame, rear cylinder heads( as long as their not aluminum), and block. I know you said you put this engine into your jeep (I have one too, a 1989 Wrangler Sahara) so I dont know how you wired up these grounds but your best bet it to find the wiring diagram for your ECM and make sure every single ECM ground is 100% grounded.

 

I have re-grounded the ECM wires to the block. Nothing! The block is grounded well...

I have been troubleshooting this for over 6 weeks now, and am pulling my hair out!

 

hmm well something is causing the ICM to be triggered into priming the fuel pump everytime you turn on the headlights and draw current. Why don't you try to remove all grounds from the engine block just to see if the fuel pump will still prime whenever you turn on the lights... Remove all grounds from the block except for the battery ground and try again. If it still occurs then at that point try removing the two pigtail connectors on the distributor and see if it still happens...

 

I forgot all the details but basically the icm inside the distributor is made to prime the fuel pump when its triggered, in the case of my issue, the icm was being triggered by my bad ground near the distributor that was probably just causing a change in voltage by just enough to cause it to become triggered ... Im thinking your icm is being triggered due to the same reason. The voltage going to the distributor from the engine is increasing or decreasing just enough so that the icm sees the change and triggers the prime... The ICM is grounded to the bottom of the distributor and from there it gets grounded by the block, cam, hold down bolt, frame, etc.

 

It turns out that the culprit was a faulty EST (ICM) module. Swapped in a new one, and all the problems magically disappeared!

Thanks for helping out Napster!