the car is an 86 5.o tpi auto w/ no A/C...

when the car has been sitting for say, a few hours (or longer) it cranks until the oil pressure guage starts to move (secondary fuel pump power switch sensing oil pressure) then fires up and idles fine... I also noticed that sometimes (maybe all the time) the SES light does not come on when the key is in the on position with the engine off but comes on when the engine starts... when the car has only been sitting for a short time (less than an hour) it fires up normally (I'm thinking there is adequate fuel pressure so the fuel pump does not have to prime the system)... also the SES light usually comes on in the key on engine off position and goes off when the engine starts...

I tried slaping a fuel pump relay in on all of the locations to see if the pump would come on when the ignition was turned to the on position but I did not get any positive results (did not hear it kick on)... I was thinking that if fuel pressure was already present in the system that it might not activate (any ideas or thoughts on this?)... my next step will be to try the relay again but this time bleed off the fuel pressure between trys...

I really need some wiring diagrams to help me figure this out...

also need cooling fan diagrams for an 86 tpi w/ single fan and 87 tpi with dual fans... if anyone could help me out with this it would be greatly appreciated... the 86 does not have A/C and the 87 does have A/C...

zroc

 

Zroc,

The ECM will operate the fuel pump for about two seconds when the ignition is turned on. As long as the ignition has been off for at least twenty seconds, the ECM will operate the pump again when the ignition is turned on, regardless of pressure in the fuel rails. The FPR maintains fuel pressure in the rails and dumps excess fuel back to the tank. The fuel pump runs continuously when the engine is running, and all excess fuel is returned to the tank in the same manner. There is no pressure sensor for fuel pressure, so the ECM does not monitor it and cannot operate the pump based on existing pressure.

If your fuel pump is not running after a twenty second (minimum) shutdown, you may have a failed relay, ECM problem, or wiring problem.

Another problem that you mentioned may be related. The MIL lamp should turn on for about ½ second, off briefly, then back on when the ignition is first turned on. The lamp should remain on until the engine is running. Your lack of the MIL lamp may indicate a problem with IGN power to the ECM, which could account for the lack of a fuel pump priming cycle.

Start looking at the electrical connectors at the ECM, the ECM fuse in the panel, the IGN circuit, and the ignition switch. Since your fuel pump eventually operates, the FP fuse is likely O.K.

This might give you a start:



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Later,
Vader
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If you want to beat the World, it might reach up and pull you down...
Adobe Acrobat Reader

 

Thanx a bunch Vader... all the alpha numeric on the right side is the pin outs for the ECM right??? (the manual I ordered is taking its sweet time getting here)... this sounds like it will be a fun project...

thanx again...

zroc

 

I have not had much time to mess with this car... it still has the long crank thing going on (fuel pump not comming on when the key is turned to the on position)... the SES light was still not comming on with the key in the on position but I giggle the key and the light came on (still did not hear the fuel pump)... then the SES light started to behave like Vader described but the fuel pump is still not priming... after it sees oil pressure the cars starts and runs great... but still after start the occasional code 54 (low fuel voltage) SES light situation rears its ugly head... I need this thing fuctional and reliable for the woman and soon... please if you have any info on this point me in a direction...

ps... I got the coolant fan working properly... *** knows how... still wish I had the diagrams for the 86 single and 87 dual fan circuits...

zroc

 

bye bye double post

[This message has been edited by zroc (edited November 22, 2001).]

 

I believe I have the answer to your problem. I went thru the exact same thing as you describe. My problem was solved by curing 2 separate problems.
First the code 54 showing up--solved that by replacing the ECM. I tried replacing the relay first but that did not work. After replacing the ECM I never got a code 54 again and I always here the pump prime when ignition gets turned on.
This however did not solve the long cranking. This turned out to be a leaking injector. I checked the fuel pressure and found it to bleed off quite rapidly after shutting off the engine (within 20 min it was down to 0 psi). By pinching off the fuel feed and return lines and still seeing the fp drop I figured that was it. Further tested by pulling off the plenum and lifting the fuel rail and priming the fuel system. The #1 injector leaked like a seive.
I would check your fuel pressure first but here's the recap on my fix:Replace ECM--fixed the code 54; check for leaking injector.
You would not believe how my car starts now--probably better than new. And I lived with this problem for 5 years before actually trying to figure it out.
Hope this helps and sorry it was kinda long.

Bob

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350 TPI, 700R4(rebuilt), K&N's, MSD 6AL, Headers, Flowmaster, 160* stat, airfoil, MAF screens cut out. 13.88 @ 101.18 mph

 

must of had a time warp or something???

 

What???????

Bob

 

for some reason this post would not let me view anything after the nov 12th post even though it was showing additional post after that date... it stayed like that for two or three days...

anyway... I still have only had time to check the grounds under the hood... I seem to remeber someone mentioning a problem with the 86 tpi ecm (i wonder what it will cost to replace it???)... I need to find the power feed from the ignition to the ecm, the reason being is that after jiggling the key in the on position the SES lite started working... could this possibly be a problem in the ignition switch??? if so, what in the hell am I looking for??? also can anyone tell me were the ecm grounds might be located under the dash??? money and time have become way beyond tight (and I have my 87 that I need to finish for myself)...

thank you for all the help so far...

zroc