Surging

[butterball]

i have a surging problem on my gmc 1500 1992 4.3 it will surge at steady speeds. this will be only after it has been drivenand after the enging is at full temp. and it is shut off and restarted will it surge. i can drive it 200 miles will run fine till it is shut off then restarted will it start surging. it can be turned off onlt 10 minutes. i have replaced fuel pump. fuel filter , plugs egr selinoid, egr valve used distributer. net dist pick up , cap rotor. cant find a vacuum leak. im at a loss.check eng light does not come on. any ideas ? oh 305.000 miles on it.

[XYZ]

I'd hit the throttle body with a can or two of throttle body cleaner, and while you're doing that, disconnect the battery and let the computer reset itself to the lack of carbon you'll create by cleaning the throttle body. You only spend about 6 or 7 bucks on the cans of cleaner, which if it has 305,000 miles, I'm sure it needs to be done.

[butterball]

never thought about that. any one brand work better than another ?

[XYZ]

No, I usually buy the store brand of whatever auto parts joint I happen to be in at the time....

[butterball]

thanks will try than monday.

what i can not figgure out is why it will only surge is after i restart it .when the engine is at or near normat temp. if it cools down below say 125* and restart it if will be fine. it idles fine put the gas to the floor its fine but at a steady speed it will start surging . i have used luckus(sp)in the tank 3 times no change.

[desrtrat]

thanks will try than monday.

what i can not figgure out is why it will only surge is after i restart it .when the engine is at or near normat temp. if it cools down below say 125* and restart it if will be fine. it idles fine put the gas to the floor its fine but at a steady speed it will start surging . i have used luckus(sp)in the tank 3 times no change.

check for a vacuum leak when your at temp. on older vehicles that used a thermal vacuum switches it was a common issue. engine ran fine until the switch opened and caused a leak some where in the system.. also ..you may be getting a bad signal to your EGR

 

good luck