Rough Re-Start When Air and Engine is warm

[Sven]

I noticed this problem last year when it got really warm here in the summer, (It only gets real warm and humid a little in NW Minnesota)

If its 75-80+ my Expy re-starts like garbage after its sat for 20min-60min on a relativly warm day.

It seems to fire right up but seems like its pig ritch and idles rough for 2-3 seconds. You can smell the raw fuel.

Last summer my MAF/BARO sensor was replaced and it did not help.

I was thinking since my immediate restarts are fine that it must be a coolant sensor??

Just wondering if anyone has had this problem.

 

[toms89]

I had similar issue with my stang several years back but it was also hard to start. I assumed leaking injector(s). I thought over a bit of time it would flood intake upon shut down. Wait longer and it would evaporate and start fine. My theory.

Ended up injectors were fine so I tried thinking of other possibilities for potential fuel leaks. Only thing I could think of was fuel pressure regulator so I tested it and found it was leaking fuel via the vacuum line to the manifold. I guess there was a pin hole in the diaphram that would leak down the fuel pressure over a bit of time after motor was shut off. With motor running it was mild enough to go unnoticed. After replacing the fuel pressure regulator I had no more issues.

So I would consider injectors or fuel pressure regulator as possible sources. I also had a fuel pressure gauge so I knew fuel pressure was dropping to zero over time after shut down. This was not all that unusual as the check valves in the pumps are known to bleed down.