Gmc trucj

Asked by Feb 09, 2016 at 03:05 PM

Question type: Maintenance & Repair

I have an 85 gmc Sierra classic, it starts hesitating
with acceleration at 45mph, now when I got to
start it it starts at a high idle roughly 3-4000 rpms,
im thinking it may be a vacuum line but im not
positive, can anybody help?

5 Answers


It is probably a miss, check cap & rotor, wires and spark plugs.

1 out of 1 people think this is helpful.

How long since a tune-up? Any applicable trouble codes? Your obd1, you should be able to check some codes, yourself, if there are any. Make sure throttle valve is closed. Block off the mouth of the throttle body, it should kill the engine. If no effect on idle, you are getting false air in there from somewhere.

Im not real sure I got the truck about 3months ago, I know the plugs are shot and not gapped correctly, it has a few vacuum leaks and the timing is off just a hare, its been this way since I got it and it just started doing this today, I will check everything and see how it goes thanks


Any of that could be causing your problem, Giver a good tune up.

1 out of 1 people think this is helpful.

Thats my thoughts exactly, thanks for your help I really appreciate it

Your Answer

Add photo

Related Questions


Search Maintenance & Repair Questions

Maintenance & Repair Experts

#1 Tom Demyan
Tom Demyan
Reputation 165,610
#2 dandyoun
Reputation 90,410
#3 tenspeed
Reputation 73,270
View All