hey all....

i have a 1989 chevy 4x4,2500 6 lug. the truck has a new engine in it with less than 6000 miles on it (goodwrench HO 350). one day about 2 weeks ago i was up deer hunting and the check engine light popped on, and the thing started surging real bad ,no power,etc,etc. i drove it home ( about 15 miles away) and took it to my neibor and mechanic. keep in mind that the truck generally runs like it just came off the showroom floor.


now, we checked the trouble code, and it read that it was running real lean. he hooked it up to his diagnostic machine, and it said that it wasnt getting the O2 it should so we replacxed the O2 sensor. no good. so far we have replaced


O2 sensor
temp sensor
MAP module
intake gaskets ( it had a small leak)
computer ( plugged in a new one and tested it,same thing,no change)
fuel filter
throttle body base gasket
fuel pump in the tank ( which we havent checked yet, and it could be causing it i suppose)


i got it back yesterday and it ran like new again. this morning, i took off to go hunting AGAIN and i got about 10 miles from home and the light popped on AGAIN and it started running real crappy and surging AGAIN.....

now, like i said, the truck ususally runs like brand new.


all the diagnostic computer stuff says everything fine,exept its running lean and the computers trying to compensate for the problem by spraying more fuel thru the injectors ( throttle body injected of course). im on social security and cant keep pumping money out just replacing things in the hopes that it will fix it.





any suggestions'?

 

if it surging iac (idle air control) just chek the line pressure for the fuel with that year it has to be excatly in spec or it wont run right. i would also through a vacum gauge on to see if you were losing vacum but im pretty sure its the iac

 

2 grounds you need to check...
near the thermostat housing..1 ground goes on the housing...the other ground GOERS TO AN INTAKE STUD...If they share the same ground,she'll run ignorant

 

i double checked both of them myself. i even put now ends on them and soldered them on...no good

 

well, its all fixed. we found it was the fuel pump...thanks for the replies

 

good find...a "weak" pump can be a real bear to diagnose