I've had the weirdest start issue for quite some time now. I've taken it to 3 mechanics after trying to troubleshoot it myself and no one seems to be able to fix it.

Here's what happens:

Cold start - truck starts fine.
Warm up truck, turn it off, start it immediately - starts fine.
Warm up truck, let it sit for 30+ min, turns over but won't start. At this point, giving it a hint of throttle starts her right up.

I have fuel pressure at start, I have spark, one mechanic thought it was from a dirty PCV valve and cleaned that out as well as the throttle body (I had previously tried cleaning the throttle body to no avail so I knew that wouldn't help). This issue is driving me nuts and I just can't figure out what's going on with it. Any ideas??

Thanks!

 

Kinda sounds like vapor-lock. TPS might be whacked.

 

Hmm I mean the 0 and WOT readings on the throttle check out ok but it's possible that it's off somewhere in between. I could see it being a scenario where conditions dictate the throttle should be at 5% for a hot-start and the TPS reports it there but throttle is sitting at dead zero in reality. Is the TPS on our trucks built into the TB like the IAT sensor? Cause if that's a cheap replacement I might try it just to entertain the possibility.

 

Any check engine lights by chance?

 

Negative. It seems like the throttle is working properly too. Cold start it opens to 6% and starts right up. When its having its trouble when warm it only opens about 3-4% but that's all the ecu is demanding. Sit your foot on the throttle slightly and it starts up.

 

reset pedal yet? not that it matters..

 

Yes tried that

 

When it turns over, does it attempt to fire? You only need three things for an engine to run. Spark, Fuel and timing. If it doesn't even attempt to start, then I would start looking at electrical. Usually with fuel related problems you get changes in RPM during cranking as the engine attempts to fire. The TPS issue does also seem viable though.

 

It does attempt to fire, im getting spark and you can hear the beginnings of it catching. The weird part is there seems to be no attempt to adjust the idle during cranking... it'll just crank and crank until you tap the gas.

 

I know this isnt the same but years ago i had an Olds 350 and it has a distributor cap and button setup. Timing was adjusted by turning the distributor CW or CCW. With it advanced the engine ran better. But get it too far and (like you) after the engine got hot and was shut down, when you tried to start it back up while it was still hot you would have to turn back the timing.