floods on warm start up
 

1989 chevy k1500 5.7 L will start and run fine when engine is cold but when hot, starting is very difficult and clearly is flooding.

I would think,cts,not reading the warmer coolant,still thinks it's a cold motor

You use good gasoline? Any gasoline additives? If not sound like TBI injector issues to me.

I should have given more detailed background on this pickup. It all started when I was unable to restart with warm engine. No fire what so ever and I assumed no fuel but did notice a strange odor, the same odor on every attempted warm engine restart. I blamed the fuel pump but after determining the cost of test adapter I opted to just replace the fuel pump. That did not solve the problem, so replaced the fuel pump solenoid. That did not correct the problem so rebuilt the fuel regulator and injectors. That did not change the hard start with warm engine but did notice a slightly rough engine idle while cold and as has always been the case, a 1200 rpm idle speed. The PVC valve rattles and so I assume that is adequate and did find a vacuum leak, but plugging it did not seem to make a difference. I have discovered that depressing the foot feet on warm start up will bring the engine out of an extreme flooded state and get the engine running. The fuel has some Sea Foam in it but wonder even though some of the fuel may be old (several months) if that would affect cold starts as well. Also the engine has almost 150,000 miles but after a cold start, I can take it on the road and accelerate and have good power for the miles on the engine.

Cts, maybe?or grounds on intake that affect that circuit

Or weak spark, ignition control module going bad with heat?same with coil?

Would temperature gauge show warm coolant if cts was not operating properly? Thanks for response!

Yes,two separate sensors,cts for ecm,the choke,for cold starts

As of today, two warm engine restarts and excellent performance during road tests including hard accelerations, the warm engine start ups are perfect. I have eliminated the cold engine butterfly in the intake to assure cool air delivery during warm engine start up. I do notice a definite time lag in engine warm up during cold starts but glad to sacrifice that if it in fact it cures the problem. We will see. Thanks to all for the suggestions.

You are correct. It was the cts. Ohm check showed infinite resistance. Replaced it and now cold engine starts with 1400 smooth rpm's, that slowly slows to 950 and just as smooth as can be. Hot starts are perfect. Thanks!