Backfire and stalls
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
Backfire and stalls
i own 1989 Z51 6 spd. It started to backfire and stall. It will idle for ever and it accelerates well. But, slow down and it will backfire and stall. Good compression, plugs look great. They are new, wires are new.
Timing chain?
SES light is on.
Thank you
Timing chain?
SES light is on.
Thank you
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
I am guessing that FPR is fuel pressure regulator. Check it? remove the line a smell for gas. If so is the fpr nfg? thank you
clean the throtle body. spray fuel injector cleaner into the tBI?
thank you
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
I was reading an article on backfiring. It said that backfiring in the exhaust is unburned fuel and that on a car with an air pump the GULP valve(s) may be bad. I am thinking that the gulp valve the way that the article describes them are the two valves fed by the AIR pump. I am also thinking that if I plug the lines to the valves and the backfire may stop.
The article also mentioned a lean code. My mechanic said the car had lean code.
Any ideas comments. Thank you
The article also mentioned a lean code. My mechanic said the car had lean code.
Any ideas comments. Thank you
Race Director
Joined: Mar 2015
Posts: 15,926
Likes: 579
I was reading an article on backfiring. It said that backfiring in the exhaust is unburned fuel and that on a car with an air pump the GULP valve(s) may be bad. I am thinking that the gulp valve the way that the article describes them are the two valves fed by the AIR pump. I am also thinking that if I plug the lines to the valves and the backfire may stop.
The article also mentioned a lean code. My mechanic said the car had lean code.
Any ideas comments. Thank you
The article also mentioned a lean code. My mechanic said the car had lean code.
Any ideas comments. Thank you
sounds like it is dumping fuel just do the free tests first might even be a o2 sensor. Can you get a scanner on it while it happens? 
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
I have the scanner software for the ALDI connector will that give me any information. The O2 sensor has about 1000 miles on it. Thank you for the help
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4th Gear
Joined: Sep 2018
Posts: 4
Likes: 0
hello guys i'm from europa and i'm new in this forum and i need help with my amcar. after i cut catalistic converter,blocked egr and deleted smog pump my corvette crossfire1984 starts backfires through the tbi's. i checked compression, tested ignition timing 6 degrees,fuel pressure 12 psi, map,o2,tps,temp sensors works good. new spark plugs and wires new distributor new intake manifold gaskets,new iac. adjusted valves. no fault codes. and still this samme problem. i have no ideas what i can check more. please help me to solve that problem. i promise big beer box for good help. p.s sorry for my english
Thread Starter
Drifting
Joined: Feb 2013
Posts: 1,464
Likes: 48
hello guys i'm from europa and i'm new in this forum and i need help with my amcar. after i cut catalistic converter,blocked egr and deleted smog pump my corvette crossfire1984 starts backfires through the tbi's. i checked compression, tested ignition timing 6 degrees,fuel pressure 12 psi, map,o2,tps,temp sensors works good. new spark plugs and wires new distributor new intake manifold gaskets,new iac. adjusted valves. no fault codes. and still this samme problem. i have no ideas what i can check more. please help me to solve that problem. i promise big beer box for good help. p.s sorry for my english
Good luck
4th Gear
Joined: Sep 2018
Posts: 4
Likes: 0
Typically this is a cam shift/valve train problem. This happened to me. What you should do is remove the valve covers and then put a socket wrench on the crank shaft bolt, 5/8", and slowly by hand rotate the engine. You will probably see that one of the intake valves is not opening. To determine the cylinder 1. run the car. 2.remove a spark plug wire. if the backfire does not go away replace the wire and remove the next wire. When you get to the cylinder that is backfiring. The backfire will stop. Then remove the valve cover and check. Could be a broken push rod or loose rocker arm. But, most probably it is a cam shaft lobe. My cam shaft lobe was so worn it looked like a journal . Remember the cam shaft is hardened but only the first 0.015". So a nick or over tightening the cam will wear out, quickly.
Good luck
Good luck
Burning Brakes
Joined: Feb 2013
Posts: 1,173
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From: norway