What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Chev1991 Problems Please HELP

T

tractorman

Registered Member
Joined
May 16, 2006
Posts
11
Reaction score
0
Location
houston texas
Problem with a 1991 chevy truck 350 tbi, ok when it warms up a little it will die, at every stop sign or at idle I have had it at two mechanic and they can't figure it out either they both hooked up their scanners up to it but no codes show except for egr because it off have a plate on hole. Here are the items I have replaced so far the pickup coil in distributor, distributor cap and rotor,module, oxygen sensor, tps sensor, fuel pump pressure switch, temperature switch,spark plugs,tryed a different throttle body did the same thing. Changed out ECM also check fuel pressure around 14.Tryed a different coil, knocks sensor, map sensor, new gasket on throttle body changed out intake gasket. If anyone else every had the same problem please let me know I AM STUMPED. The truck does have a few miles on it 314000 but still runs good once you get going also if you floor it will drop down like nothing there but then take off like a bat out of hell, every time you let off the gas it will do the same thing.
 
My '90 K5 did a similar thing and I replaced basically everything you did. My truck has 256k miles on it. Turns out the truck had "jumped" time. I don't know if thats your problem or not. My truck would crank and if you revved it it would run. Just idled like crap. Good luck with yours. I know it seemed like I would never get mine figured out. The bad thing with mine was when it jumped time it bent a valve. The good thing is that instead of going to all the work to fix it and still have a 256k motor I just pulled that engine and I'm now doing a MPFI BBC swap. :D
 
Take it to someone with a fuel flow meter. I had a similar problem and replaced the same things. What it ended up being was the baffles came loose in the gas tank and knocked the fuel pump silly. Then on top of that there was an o-ring in the injector body that had gone out so the fuel was just leaking into the manifold causing it to flood out. At least that's what the mechanic I took mine to told me, and my truck now runs like a scared rabbit. ** I may have misquoted that, but either way my 88 Jimmy runs just fine.
 
tractorman said:
Check timing several times always right on top dead center. Thanks for reply.
Click to expand...

I could be wrong on this but I think if it "jumps" time it will give you the illusion that it is in time when it actually is not ie. a timing light will show that it's in time, but b/c the chain has jumped a tooth or two it is actually not in time. That was the case with mine anyway.

I also had this exact same thing happen to a boat of mine. The boat had a 225 ci Buick V6 and we actually overhauled that engine. We put it back together and it still wouldn't run right. Ended up the timing gear had the nylon teeth on it and some of them had broken off. The chain jumped a few teeth and it was out of time. However, we checked it numerous times with a timing light and it checked good.
 
From the Manual: Engine Stalls.

1. Idle speed incorrect - faulty IAC

2. Fuel filter clogged and/or impurities in the fuel system.

3. Damaged or wet distributor cap and/or wires.

4. Emmission system component(s) faulty.

5. Faulty or incorrectly gapped spark plugs, faulty plug wire(s).

6. Vacuum leak at the throttle body, intake manifold, or vacuum hose(s).
 
did you change the fuel filter??? That always seems to be a good cheap thing to replace that can definitely cause problems...
 
have you adjusted minimum air on the throttle body?

Also,

did you make sure you sealed that EGR blockoff plate really well? You need to make sure there are no leaks from one of the EGR passages to the other. If there is a leak, it will die like that because the engine will seem like the EGR is installed and blocked in the open position.
 
I once saw a cracked reluctor ring in the distibutor. Ran great cold but when warm it would throw the timing way off and stall. Didn't produce any codes either.
Don't know if it's your problem but it's a strange one I came across. Good luck.

Keith
 
Did the minimum air adjustment to throttle it helped a little still die some time. Still has that dead spot when you take off or let off gas and give it gas again. Did't give up yet still rechecking everything . Thank for reply about the air adjustment.
 
at idle, how does the spray pattern of the injectors look? It should be a nice fine cone, no drips or large drops in the spray. If it is dripping, you need to replace the injectors.

I guess it could also be a vacuum leak at the throttle shaft. The TBI's tend to do that when they have high mileage. The bores start to oval out, and a vacuum leak will start. To test for that you can spray carb cleaner at the throttle shaft on the outside of the TBI. If you're idle rises for a bit, then comes back down, you have a vacuum leak there. Only way to fix that is to get a rebuilt TBI base.
 
Spray pattern at idle looks fine cone spray. Checked for vacuum leaks around throttle shaft and vacuum lines sprayed carb cleaner all around them no change in idle. This is a tuff one. Thank for reply.
 
If you can't find an answer here you can always check www.thirdgen.org

They deal with fuel injection quite a bit more, even though it is a camaro board. A lot of the TBI people use it for reference.
 
Have you burnt a new chip to disable the egr function? As far as I know the egr operation effects timing too. I'm not to sure on this as I still have mine connected but you would certainly get some info on it over at thirdgen.
 
with this being a slightly off idle issue, I doubt the EGR function in the ECM is the problem. EGR shouldn't be active then anyway. But it is a good idea to get it programmed out if you decide to run the motor like this permanently.
 
You must log in or register to reply here.

Latest Posts

Top Bottom