1990 TBI 350 won't start when hot

[Zukyota]

OK, be gentle....chevy newbie

I tried a search, but no luck.

A buddy of mine has a 1990 GMC that will start and run fine when cold, but not when hot. When the truck warms up, it idles poorly, then will not restart.

He's getting diag. code 15 for coolant temp sensor. I understand that the coolant temp sensor would affect the idle, but will it cause the truck not to start at all.

He's checked fuel tank vent lines for blockage and he can see fuel spray from the injectors.

any help appreciated.

[440ex]

after its hot and cools does it start fine again ??? if the TB squirting gas once its hot .....i had a TB motor just a few months ago run great till it was hot ,then it wouldnt start till it cooled off ..it didnt thow a code either ...totally strange .it turned out to be a bad fuel pump relay

[Rastus]

yes, the coolant sensor will in fact cause the issue you are having.

[zkrawler_04]

could it possibly have the timing set too far advanced?....did that on my 90 TBI chevy and caused the same problem when i did my headgaskets

[jays68yak]

possibly a starter? I had issues with my 94 not starting, changed out the starter and it has been good ever since. well except for that time that I lost a starter bolt.

[TatorZuk]

Originally posted by Zukyota
He's getting diag. code 15 for coolant temp sensor.

Code 15 is low temp indicated, sensor tells ECM it's -35*, ECM adds fuel, probably enough when warm to flood engine.

Disconnect sensor, jumper the harness connectors together. This will trick the ECM into thinking it's +260*, go test drive. I bet it will run way better when warm.