Failure to start after short trips, any help much appreciated!

[sooby]

howdy folks,

My JDM 1996 GC8 wrx is failing to restart after short trips, example: left work after eight hours parked and car starts fine, travel maybe 1 minute down the road to servo to fuel up, go to restart and engine cranks but won't start!

This happened previously in February this year too, when I had to move the car out of the way (literately meters, and again it wouldn't restart. Got a jumpstart and that seemed to sort it.

Battery is less than a year old. Tested with a volt meter today and voltage was about 12.2volts so I charged it for about 10mins until it reached 12.6 volts.

Car is due for a service soon anyway - where should mechanic be looking for problem?

Any help much appreciated!

[Rosssub]

12.2v is a bit low, is that after a bit of cranking? What is it showing while your cranking? Could be a weak battery/tired alternator/loose belt/loose, dirty or corroded terminals/earths etc.

Do a diagnostics check to see if it's given any codes at all. Could be something weird like a crank sensor CEL when it's not starting.

If everything seems ok and it's got fuel and spark, then check out the coolant temp sensor. Might not be telling the ECU that the engine has warmed up a bit when your trying to restart it, so it's over fuelling.

[boon]

Are you running a Link?

Excess startup enrichment, floods it somewhat, try cranking it with a bit of throttle.

[sooby]

 Rosssub said:

12.2v is a bit low, is that after a bit of cranking? What is it showing while your cranking? Could be a weak battery/tired alternator/loose belt/loose, dirty or corroded terminals/earths etc.

Do a diagnostics check to see if it's given any codes at all. Could be something weird like a crank sensor CEL when it's not starting.

If everything seems ok and it's got fuel and spark, then check out the coolant temp sensor. Might not be telling the ECU that the engine has warmed up a bit when your trying to restart it, so it's over fuelling.

Thanks again Rosssub.

12.2v was at rest, will try reading when cranking. Will mention your thoughts to mechanic too.

[sooby]

 boon said:

Are you running a Link?

Excess startup enrichment, floods it somewhat, try cranking it with a bit of throttle.

Cheers - definitely no Link here, would have thought its not running rich as it doesn't have the telltale black stains above the exhaust pipe.

Did try cranking with full throttle and no luck

[Guitar_Guy]

My older Legacy did that, had to get atleast a bit of warmth in it before turning it off after its first start for the day.

Turns out it was flooding, now I might be way off on this so correct me if I'm wrong but I believe when the engine is cold

more fuel is injected to keep the rpm higher (1500rpm) while warming up, then when you turn the car off and it is still in its

"warm-up period" the excess fuel floods the engine.

I know there is a bit more to it than that but I'm by no means a mechanic and far from being knowledgeable enough to fix my own problems.

Just sharing my own experience to hopefully shed a little light on your problem.

[Steviep168]

Might it be the crank sensor as i used to have similar problems with My96 STI back in the UK.....

[Joker]

coolant temp sensor as someone mentioned it might be flooding may cause this (lives in the cross over pipe under the intake)

my old 90'GT would stall & not restart when cold (yes an auto stalling is very weird)

Edited June 28, 2015 by Joker

[sooby]

thanks for the help fellas, any idea how to narrow it down further?