i have a 97 c2500 with the 5.7. after i start it up after sitting 4-5 hours it seems to hesitate when you are going to speed up (get to about 15 then starts to hesitate) then after 8 secs of hesitation it comes alive like nothing was ever wrong. and you wont have this problem till it sits again. hilarious

 

How many miles on it?when was the last tune up?sounds like something gets heat soaked and sticking,did you try some techron or seafoam? are there any codes stored

 

the truck has 180k the motor has 60k and the transmission has less then 7k. there is a code the will turn on after going down the highway for 30 miles then 10miles after that it shuts off. and last tune up was maybe 4k ago. when i did the tune up i ran seafoam through it. truck sat for a year before i got it and put the tranny in.

 

Sounds like you have a leak in the fuel injector unit. It hesitates until it burns the fuel that has leaked into the intake. Most likely it is the regulator. When you park it look inside the intake through the throttle body, after sitting 4-5 hours look back inside. Do you see puddles of fuel sitting inside?

 

i didn't see any wetness or anything when i looked down the throttle body.

 

Did you pressure test the fuel system?

 

Did it start bad RIGHT after you looked in?

 

let me explain it better. after it sits you can jump into it and start it and you can rev it like any normal engine but when you put it into gear you can get up to about 15 then it falls on its face then after 5 secs (no matter how much throttle you give it it will still feel like you don't have much power for then 5 secs) or so it comes back alive. only time it doesn't do it is when it runs for a 3-5 mins then you take off

 

no i haven't pressure tested it because i don't have a gauge to do it right now. I'll see if my schools shop has one on Monday when i go back for class.

 

the code is still probably in there if you have an autozone close by they will scan it for free