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89 GMC - PLEASE HELP!!! Having issues with stalling and ru

GMC Work Horse

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GMC Work Horse New Member

GMC Work Horse

Posted
Posted
Hey there guys!


I have a 89 GMC 1500. Just recently it has begun bucking, popping and stalling on me. 5 days out of the week it will run fine, but those 2 days it starts acting up. Of course I am being somewhat facetious, but also serious... for the most time, it will run good, but then out of the blue, it will start this jerking, popping, and stalling, as I a driving. It usually starts within 20 min of the drive, I always say, when it gets hot, but the temp is good.... however, a few weeks back, the temp was buried in the RED and the radiator had little water in it so I filled the rad and a few days put some stop leak in it. Not sure were it was leaking, since I never noticed water, and I am not sure how long I was driving, while it was in the RED, but the heads and gaskets seem fine. Now I can't recall if this bucking and popping was happening, prior to the rad/water issue, but no doubt, it's happening now.


For example... Thursday night, I had a friend come over to try and figure what was going on. So we drive around to try and get the truck to do its thing... I hit WOT a few times to get it hot and nothing... ran like a champ, for the most part... then on Friday, I had to go pick some freight up and my same buddy went with me. about 15 min or so into the drive, the truck started bucking... then stopped (bucking)... then a few min later, it started popping, through the TB, or so it sounds like... then every time I started to slow down, it started wheezing and popping and bucking more, then if I didn't hit the gas... HARD, it would stall out. If we hit a red light, it would definitely stall and to make the green, I'd have to put it into N and give it gas to GO...


Some are saying IAC, some are saying MAP or MAF, whichever one... I don't have a lot of money to blindly replace things so I'm hoping to get better EDUCATED guesses, if you will, here.


Please hit me back ASAP, please! This is my only truck, and it's what we use to move my handicap mom around since she is in a wheel chair.


Thanks guys!!!

barry G Senior Enthusiast

barry G

Posted
Posted

Is it throwing any codes?

 

Have you checked the cap and rotor for carbon tracking or other impurities?

 

my first guess.

is it humid out or dry, to coincide with popping.

 

most electric is bad or good, but cap and rotor and wires can play games like this.

if one goes out, the coil has a different charge to smack a good one into different timing.

 

Not much for real tune up, coil included.

 

the most common wires flunked is the back. Short cylinder wires. Very hot there.

 

TB may not notice equal length wiring, but I'd try it.

GMC Work Horse New Member

GMC Work Horse

Posted
  • Author
Posted

Is it throwing any codes?

 

Have you checked the cap and rotor for carbon tracking or other impurities?

Sadly this truck is old and was used as a work truck so many of the lights on the dash don't work to read codes.

 

I they show obvious use, but nothing crazy as for the impurities, I always said that when it was appending, it felt like what happens when there's water in the gas tank.

 

my first guess.

is it humid out or dry, to coincide with popping.

 

most electric is bad or good, but cap and rotor and wires can play games like this.

if one goes out, the coil has a different charge to smack a good one into different timing.

 

Not much for real tune up, coil included.

 

the most common wires flunked is the back. Short cylinder wires. Very hot there.

 

TB may not notice equal length wiring, but I'd try it.

 

we live in Florida so it's always humid, lol...

Looks like I will start with a tune up.

GMC Work Horse New Member

GMC Work Horse

Posted
  • Author
Posted
Well guys there was a crack in the tank of the rad, that I never noticed and today it gave up the ghost so a new rad is in order. Does anyone know what rads swap over to this y/m&m?



I did find an issue with the IAC... when we pulled it out, the pin, or whatever you want to call it, that's inside the spring, was unscrewed all the way out. The washer was split in half so at this point, I've no doubt that this is part of the issue. Funny thing is, when we screwed the "pin" back in to 1-1/8", as the book (haynes or chilton... don't remember what I have) says, the truck ran noticeably better, though I think we retarded the timing a little too much.


Well, I guess a tuneup and IAC is in order.


Since I am broke and these damn sensors are like $40+ each, I was thinking of getting this and covering all my bases....




How do they test to see if these things are any good? Any thoughts?


Thanks guys!

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