i have a 99 GST that has kind of a dual problem. It will either not start or start and run for 30 seconds then turn off. I checked the fuel, spark, and checked for codes but i found no problems. I really need some advice on any other systems or parts could cause a problem like this!!!! Also: This is a manual trans vehicle that recently had its enging replaced

 

Does it smoke at all? I was thinking a possibly bad coolant temp sensor for the hard start.

 

when u first try to start the car a little cloud of white smoke can be seen coming from the head but this will eventully stop

 

sounds like a headgasket to myself... what color is the exhaust gasses?

 

do a compression test and come back w/the numbers

 

start with the compression test like he said. But what about checking the alternator. Have you tried jumping it and leaving it to let the battery charge. See how long you can get it to stay running while still on the jumper cables

 

I think this is electrical.

Could be ECU or cam sensor going out.... however, I would do a compression test like the guys said.

 

i did a compression test and all cylinders are averaging 150+psi

 

Well you can assume the engine is in healthy condition. When it dosent start try spraying 2+2 into the intake and see if it fires right up.

 

take it to autozone and have them test your alternator, and also your battery for the hell of it. its free so why not