Skiviking

86 928S... fuel pump replaced a couple days ago with filter, strainer hose you anem it...upon firing it up it ran rough for the first30 mins...then would crank but not fire.....put in new fuel pump relay..nothing... Sat for about an 1hr or so....went and cranked and fired up... got home.. shut off, nad refired it a couple times to see if it would happen again...everytihgn ran fine. Yesterday, fired it up ran about 70 miles no problem..ran great. Went out today, fired right up, went and got some gas. Came out of the store..no fire, just cranking over... Could this be a symptom of a failing green wire?...all else seems fine.. Any help is appreciated..

neilh

No green wire on an 86 - but you are on the right track - think electrical !

dogleg

agreed,have you checked to see which you are missing when it wont fire,spark or fuel?

davek9

Crank Pos Sensor would be my next replacement if it is not a new one. It can be scoped or you can just shotgun it

Mrmerlin

replace all 4 of the running relays,
ignition,
EZF,
LH ,
and fuel pump,
also check that the fuel pump fuse is good or replace it
Next check that the fuel dampers and FPR dont have vacuum lines smelling of gas

Skiviking

Brand new fuel pump, filter, hose and strainer from 928RUS and all new relays...I pulled the cover off the relay for the fuel pump and can see it switch over when the key is activated all relays new too... The car always starts right up when cold..if given an hour after a no start it fires like nothings wrong...drive it 10 miles shut it off for a couple minutes and try...it only cranks not firing... I'm now thinking it might be temp related...thinking the fuel pressure activator on top of the engine might be the culprit since it looks like it is temp activated to keep fuel in the lines for a refire? I think its allowing the fuel to drain out until the system equalizes..then it allows a quick start after it sits no problem...

Glenn M

I have a problem like this on my 87. Doesn't happen all the time, even less now that I've cleaned the grounds again.

When it happens again remove the battery ground for a few seconds and reconnect. See if this fixes it.

I spoke to Jim Coremnan at SITM and he said it could be the startup fuel enrichment map in the LH. Taking the ground off resets the LH.

I've tried the relays, computers, MAF, replaced the CPS and the rear knock sensor, still happens. Cleaned the grounds again and it has helped.

I have not done the Temp II sensor.

Now I need to ST my 87 and change the fuel enrichment map for startup.

Weird side effect that I have sometimes seen when this happens is that the interior lights and rear hatch release won't work. Reset the ground and all is well.

Good luck!

Mrmerlin

if your getting a no light in the interior i would investigate the fuse contacts,
they are likely melted or otherwise not making a solid contact you try to add a small twist to each blade of the fuse not too much,

ElReyos

Sounds simular to a problem I had with my 83'. Turned out to be the NTC II. It's easy to check with a DMM. The Shop Manual gives specific resistance values for various engine temps.

Skiviking

Is this a response to my problem on the 86 or the other problem? thks

ElReyos

Yes Skiviking, this is in response to the original problem you are having with your 86. The NTC II controls fuel enrichment based on engine temperature. On my car it was causing a no start when the engine was cool.

Skiviking

Thanks for the input...I will check it out...my problem is fires when cool or sitting for an hour or so after driving...but if I'm driving and stop and shut it down for 5 -10mins...it just cranks and will not fire or start... Give it 40-1hr and it fires on the first crank!...

WallyP

As has been suggested before in this thread, one of the common causes for that particular problem is fuel leaking into the intake from a leaking diaphragm in a pressure regulator or dampener. It is fast, easy, and free to check - all you need to do is to pull the vacuum line from each of the units and check for any traces of fuel in the vacuum line. Rub the end of the line on your finger and then smell your finger.

Skiviking

Thanks Wally, must have missed that response... I will check it out.

928mac

When it dose not start you need to verify that it has spark.
Throw a spark tester in the car so that you can do that the next time it dose not start.
This way you can elliminate the electrical to the ignition.
This is also when a fuel pressure gauge on the rail comes in handy so that you can see if you have pressure.

good luck you'll find it.

Brad