1987 GMC S15 truck just goes to "idle"

RCAVANAUGH

MEMBER
1987 GMC S15
4 CYL
2WD
AUTOMATIC
151,000 MILES

I have an 87 s15 w/2.5l I4. What happens is completely irratic. I can be driving and all of a sudden the truck will go back to idle, I can let off the gas and push it again, it will try to rev back up then same thing, back to idle. I it does it when holding the pedal steady at different speeds, conditions, road terrian, ect. All I have to do is pull over, shut it off and restart and its usually good for another few minutes. I replaced the IAC valve because it kept saying "rpm + or - 50rpm from were it should be", The fuel filter, the O2 sensor, none of which helped. I dont know if maybe its the fuel pump, regulator, injector but it seems to be with the fuel system not the engine or trans, unless its a sensor. I have no idea but its made my truck a hastle to drive. Help me please

1 Reply

HMAC300

MECHANIC
48,601 POSTS

First thing to do is see if you have good fuel pressure with TBI it should be 11# 40# at lest with port fuel. But if this has the distributor an dI think it does, those had bad reluctors in the distributors and that could be the problem. It usually kills the motor when it goes bad though but will restart. The reluctor cracks on it.