[stiers]

I have been having this problem with my '89 4.3L Jimmy since I got it. It will idle fine for a bit then every once in a while the engine idle seems to get caught up and hesitate. It will come back right away but it keeps doing it like a cycle. Same thing while sitting at stop lights. Other than that it seems to drive well. I have replaced the folowing:

New Plugs(bosch platinum)
Checked the wires and replaced one i broke
New Air Filter
New PVC valve

It still has the problem with the idle and the hesitation and I am not sure what to look at next.

 

[BlazerFRS]

O.K., I'm no mechanic, but two things I woud start with would be:

1) Fuel filter

2) Distributer cap/rotor

 

[BlazerLT]

Is the temp controls on defrost when this happens? Sounds like the AC system cycling on and off.

 

[stiers]

Already did a distrubuter cap and rotor today, didn't help. Going to try the fuel filter tonight. AC is turrned off.

Chris

 

[mechanic98]

mine is doing the same thing. i've replaces ALL spark Plugs, Wires, Dist cap, rotor, Fuel Filter, um... pcv valve, new air filter ( till i clean my k&N) And i also have an '89 4.3 with 189,000 miles, Oh yeah, the TPS also. I still havn't figured it out.

 

[stiers]

mine is doing the same thing. i've replaces ALL spark Plugs, Wires, Dist cap, rotor, Fuel Filter, um... pcv valve, new air filter ( till i clean my k&N) And i also have an '89 4.3 with 189,000 miles, Oh yeah, the TPS also. I still havn't figured it out.

Mine had a sticky valve or a blown ring something that was letting massive amounts of oil into the #1 cylander. I pulled my plug and it was caked with oil. Hopefully you don't have the same problem.

 

[strombon]

Sounds like a vacuum problem. Check every vacuum line on or around the engine. They tend to break down over time or collapse intenally. Will cause an idle problem and hesitation. It did to me.

 

[tippmann243]

mines doing the same thing, but when it does it the rpms dropt to about 375 and it almost dies

 

[mechanic98]

yeah, gets the low rpm, then goes back up after a few seconds like someone hits the gas pedal, i will check the vaccum lines when i get back to my house, right now, i'm about 13 hours away. I would like to figure this out, and don't really want to take it to a mechanic and have him look at it. would like to figure out what is going on for myself

 

[91GMCsonoma]

Check EGR system

 

[crappy red blazer]

mine had the same problem , come to find out, my vacuum line that goes to stupid black ball was cracked, i fixed the vacuumleak, now its fine.

 

[Teeleton]

My hotrod does that, but it's far from stock. With the cam lope, if i'm not paying attention when it does that, the engine just flat dies on the next lope. It would run fine 99% of the time, but occasionally at a stoplight it would try to die, and i'd have to pop it into neutral and rev it a bit. SES light would come on, and then go back off. The motor was freshly rebuilt, had all new vacuum lines, and a custom chip. Even still, the low vacuum from the cam might be causing it in my case.

Teeleton

 

[drumset5994]

My dad had a 88 Silverado with the 4.3 in it about 10 years ago...replaced the whole engine...at the time, Chevy had a huge problem with a cylinder burning out in Chamber 5 on a few engines...dunno if its yours, but the effects match what we had, but all the time.

 

[lil Tom]

i had the same problem to but i check my injectors and they were bad but then my engine started knocking i think its a bad lifter but got 2 get injectors fixed cuz it wont start now but check yours its a fairly simple fix