Backfire out of the carburetor?

1988 DODGE TRUCK

115 MILES • 5.9L • V8 • 2WD • AUTOMATIC

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Every time you give the truck gas or accelerate it gives a backfire to the carburetor. Replaced spark plugs wires distributor cap coil. Had the valve cover off on the past trying to troubleshoot the problem and nothing looked off in there.

Dec 18, 2022 at 6:37 AM

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JACOBANDNICKOLAS

CAR REPAIR CONTRIBUTOR
110,190 POSTS

Hi,

This can be caused by a lean fuel mixture or a rich fuel mixture. First, check to make sure there are no engine vacuum leaks.

Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

If that checks good, my next suspect is the EGR is stuck open. The EGR is mounted on the intake manifold. See pic below.

First, locate the EGR valve. You will see a steel shaft in the center. With the engine at idle, snap the throttle to about 2,000 RPMs. You should see that steel shaft move. If it does, that indicates it is working.

If there is no movement, remove the EGR and check if you can move it using a vacuum pump.

Let me know what you find. Also, here is a link that you may find helpful as well:

https://www.2carpros.com/articles/engine-backfires-while-running

If everything checks good, we may need to perform a compression test to see if there is possibly an intake valve that is weak or leaking.

Take care and let me know.

Joe

See pic below.

Image (Click to enlarge)

Dec 18, 2022 at 2:34 PM