its on my uncle's '00 trailblazer 250. he bought it brand new and has rode the **** out of it for 7 years. it finally gave out around june or so of last year. took it to the local dealer (same place he bought it) and they re-did the top end. new piston and such. it ran great after he got it back. (yes he broke it in correctly) this weekend we went out and it started doing the same thing. when its cold, it'll start right up and after it warms up, it won't start at all. checked compression and its only 90 psi. this is the 5th time its been out. not quite 3 tanks of gas. any guesses as to what happened?

 

Still using the oil injection?
Somehow my oil tank had water in it(couldn't tell by looking in it...oil floats)
Scored the piston & cylinder wall pretty good. I rebuilt the top end & replaced the oil pump but didn't see the water was in the tank until i drained it after the rebuild.
Fortunately, I caught it before screwing up the fresh top end!

 

haven't checked that. that's one of my guesses also, the oil injection isn't working right. ever since it was new, it doesn't use much oil. he even took it back to the dealer because of that and they said it all checked out fine. might just go ahead and block the oil injection off and just pre-mix it.

 

my trailboss comp is around 90psi too will running pre mix fuel help this?? if so which ratio should i use 30:1???

 

trailblazers dont use much oil. no premix really woulsnt make any differnce on the compression. i beleave its around 40 to 1. make sure it didnt loose a head gasket.