Motor not starting after short trips.

[TheTopher]

So like the title says...my 95 2.3 liter won't start after short trips.


By short trips, I mean very short trips, like under a quarter mile. Such as driving about a hundred feet from the parking lot back to my company truck because I forgot something, or driving from one shopping center on a major highway to the shopping plaza across the street from it...or to the other side of the parking lot. Very short trips. The first time it happened, it did it because I started my truck and then shut it off to unlock my glove box.


I have never been able to reproduce it on purpose...although I've never tried driving a little bit first. Starting and stopping it in the driveway has never done it. It also never does it if I drive any significant distance.

So anyway, onto the symptoms of this phantom problem.



When it won't start, it just keeps turning over. There is no spark from either of the coil packs, and i can't hear the fuel pump running. (not entirely sure how audible that is though.) I have not actually checked the fuel pressure when it happens, it's never a moment when I have a guage handy.

So after a while, it just works. Different things have fixed it each time, the first time just pulling the battery cable and reconnecting it fixed it, the next couple times I just kept messing with it and trying to start it and after about fifteen minutes it worked. The last time it happened, pulling fuse 19 (the fuse for ignition and pcm) and putting it back fixed it.


I'm stumped. so what are you guys thinking?

 

[95Rang515]

i had the same problem twice. once because of a stuck gas pedal on the floor so i shut the key off to avoid pinging off the rev limiter and once it stalled. both times just after start up (with in 1 min) with a cold motor

 

[TheTopher]

A few of the times it had only been sitting maybe half an hour at most, probably somewhere around 10-20 minutes...other times it was totally cold. Would that really be long enough for it to cool all the way down?

 

[95Rang515]

it very well could be the 2.3s cool off very quickly and have a hard time holding at operating temp in cool weather. it happened to me to me in February about 3 days abart. it never happened again so i didnt really investigate. i would really like to know if some has a clue. I've sence sold the ranger to pay off my fines from getting my license suspened

 

[TheTopher]

hmmm, thanks for the info, mate. Next time it happens I'll make a note of what the temp is at.

 

[TheTopher]

Edit: *grumble*

Take a lesson, kiddies. Don't leave your laptop logged into your truck forums when the missus comes over.

 

[TheTopher]

So I got a fuel pressure gauge and there's no fuel pressure either when it does it. It did it three times today even after long trips. This is getting really annoying. The only thing I can think of is the PCM...has anybody ever heard of them going bad before...or maybe some other ideas?

 

[95Rang515]

not sure if this is the same for rangers but my buddie has a 92 f150. and i would die on us randomly. where the wiring harness is attached to the fuel pump it was packed with dirt. so he would hit a bump and the plug would move ever so slightly and the truck would die we just had to push the plug in and it would fire right up. it was just a thought when you said there was no fuel pressure. did you check if there was spark. if theres no spark then i would deffinatly say it was the pcm or that the pcm wasnt gettng power

 

[TheTopher]

No spark, no fuel. I talked to the senior mechanic while my company truck was getting new brakes put on it and he said that it's definitely the pcm not doing it's job, however it could be the crank or cam sensors not telling the pcm that the motor is cranking, thus causing the pcm to not give the engine fuel and spark. So I guess that'll be my next thing to look at.

 

[TheTopher]

So after screwing with the problem for about two months total I finally just sucked it up and took it to a shop. Naturally it started up every time for them until they'd had it for a week. They said the diagnosis machine said the computer had no voltage, so their first attempt was fixing the ignition switch which did not fix the problem. So then I put it back in and they had it for a few days and they replaced a relay between the ignition switch and the computer and it seems to be fixed so far (I've had it back about two weeks now) They said what they think was happening was that after so many starts the relay would heat up and just take a dump on itself, and after it was left to cool for a while it'd be good.