Engine hard to start when it is warm

[supraGhost]

When the engine is cold, my car starts fine. once the engine is warmed up, if i shut it off, it will start right back up. but if i shut it off and come back a few minutes later, it will fire right up but idle super low and shut off (depending on how long the engine has been setting). if i let it sit for an hour or so it will just idle low for a few seconds and then it will idle normally.

its really a pain in the butt. if i come back like after buying gas, i will have to pump the throttle to keep the rpms up until it idles normally.

like i said, it starts great if i let the car cool down completely.

whats going on??


this is a 89 supra turbo 7mgte

 

[Dan_Gyoba]

Could it be heat soak?

Boiling of the fuel in the fuel rail. The resultant bubbles don't feed the injectors properly and the engine doesn't run until it gets a chance to bring up the fuel pressure.

The problem isn't so bad once the engine cools, because the fuel recondenses, so all you need to do is give the injectors time to clear the bubbles.

The solution? Well, I dunno, but it probably involves keeping heat away from the fuel rail.

 

[supraGhost]

wouldnt all mk3's do this then? mine is bone stock. what would make it boil?

 

[Dan_Gyoba]

I don't know about all, but it's fairly common. Of course that's also usually in hot weather. I can't see how, but it fits the symptoms.

 

[cuel]

http://www.supramania.com/forums/showthread.php?t=61776

Read post #3 (written be Jetjock)

 

[supraGhost]

im confused. so what do i need to do to fix this problem? adjust those selenoids or something?

 

[jetjock]

You should first learn how the thing works. That way you wouldn't be confused. That said the FPU system is pretty much superfluous as long as rest pressure is maintained. I'd be looking at that before I did anything else. Or try this: next time after it's shut off before you start it hot again jumper the fuel pump on. If the symptom disappears you'll have the answer.

 

[MA71_Static]

I had the same problem, my car ran in open loop so the ECU thought it was still cold so after it had warmed and I shut it off then started it again it would trigger the cold start injector and flood the engine, it also effects the injector by altering the pulsewidths (Thinking the engine is still cold). Check your car for any storded DTC's.

 

[jetjock]

^ Say what? Unless the wiring and a bunch of other things in your car has been modified from stock none of that is possible.

 

[supraGhost]

i never messed with the wiring on the car. i know on the way home from buying it it started jerking around like it wasnt getting fuel so i shut er down and had er towed. the shop cahrged me $300 to find a little wire and solder it.

thats all i know.

 

[supra_kid101]

Mine wouldn't start after it was warmed up either. Turned out to be the starter. I was told the magnets inside expanded due to the heat. Changed it and never had the problem again.