Vapor lock?

[scrappiedew1]

my sons 91 chev k2500 4x4 5.7 tbi , 250k on it when the temp gets above 50 degrees here in minnesota it is 60 now my sons truck will start great when motor is hot or cold when it is above 50 and the motor is mormal operationg temp if you feather the gas it will stay running and it is fine.

it has been off and on since we have had it i have replaced ,egr , idle air control , plugs cap etc general tune up stuff , fuel filter 3 years ago pump 4, now when it is winter and engine is at operating temp no problem
it seem to get better after i put a cold air intake on it , we have alot of that clean burn gas up here . any suggestions?????

 

[Black02Silverado]

How many miles on the fuel filter? Not sure what it could be. So you are saying it will not run if it is warm out, or it will run but not idle?

 

[OldCracker29]

This is the first I've heard of vapor lock since the old carb days.

 

[Texas Jim]

Based on reading the post.....
First thing I would check is "FUEL PRESSURE" when at normal temp.

 

[dirtyoldman]

This is the first I've heard of vapor lock since the old carb days.

Yup,with electric fuel pumps vapor lock is a thing of the past.Gotta be something else.Maybe the TPS or MAP sensor?

 

[Draenor]

.Maybe the TPS

Only other thing is a vacuum leak.PCV valve ?

 

[Draenor]

Oh and the gasket uner the TBI is known to detoriate, cause a leak and give bad idling.

 

[scrappiedew1]

How many miles on the fuel filter? Not sure what it could be. So you are saying it will not run if it is warm out, or it will run but not idle?

replaced filter 4 years ago 250 k on motor, fuel pump same time it starts right up when hot but if you do not feather gas a few times it dies and is hard to start now this is only when out side temp is only 60 deg or above when motor warm in the winter no problems maybe pick up coil in distubtor??i think i killed that word. gasket under tbi was done last year along with the throttle postion sensor

 

[scrappiedew1]

This is the first I've heard of vapor lock since the old carb days.

Yup,with electric fuel pumps vapor lock is a thing of the past.Gotta be something else.Maybe the TPS or MAP sensor?

done tps but never did map sensor worth a shot...just enough of a problem to keep me busy..