Engine missing exhaust backfire

My 1952 Willys CJ3/M38 with a Buick 3800 V6 has occasionally backfired upon deacceleration. Friday it was hard to start and once started it would miss on acceleration. Once the load was not as heavy it appeared to not be missing but could hear backfires from exhaust. What suggestions are there for trouble shooting?

Is that a newer engine from something like a grand am? Normally, on deceleration, popping is from an exhaust leak but wince you are missing on acceleration now too, maybe you have an ignition problem?

Pull your plugs and inspect for wet or fouled conditions.
Make sure they are snugged properly.

Check the gap and the injector.

You could have a leaking injector and your detonating on the exhaust stroke or a fouled plug from bad gaping.

Also check for an intake leak.
No matter base the checking on the plug inspection

Thanks for the replies. I have checked the spark plugs and none are fouled. I borrowed an inline spark checker and will check with that in a few minutes to insure each plug is firing. I am planning on checking the timing after that, To check for intake leaks I can spray starter fluid or carb cleaner around intake areas to see if engine smoothes out. How does one check for an exhaust leak? If you are referring to a fuel injector the engine has a two barrel carb. I do not know much about the engine. Was told, when I bought the Willys, that it was from a Buick V6 3800. Guess I need to find the numbers on the engine to get the year, etc. so I can check the specs for timing setting and spark plug gap.

Usually, you can eee an exhaust leak because there is a black soot spot

To check for exhaust leaks use the exhaust of your shop vac to blow backwards up the tail pipe. With a cold engine you could listen and feel around for for the leak.

JPNinPA said:

To check for exhaust leaks use the exhaust of your shop vac to blow backwards up the tail pipe. With a cold engine you could listen and feel around for for the leak.

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Believe I had water in the gas tank, etc. As I worked on checking the spark plugs, timing etc. it seemed to run better each time I restarted. Neighbor who just retired as a Certified Mechanic said that with all the rain we had lately that is what he would guess was wrong. Bottom line engine is running better than ever as neighbor adjusted carb, choke, etc. Thanks for your input.

Bob Snow said:

Believe I had water in the gas tank, etc. As I worked on checking the spark plugs, timing etc. it seemed to run better each time I restarted. Neighbor who just retired as a Certified Mechanic said that with all the rain we had lately that is what he would guess was wrong. Bottom line engine is running better than ever as neighbor adjusted carb, choke, etc. Thanks for your input.

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Water getting in your tank or the stations tank?

Don't buy gas there anymore.

Maybe throw some fuel line de-icer (methyl hydrate aka rubbing alcohol) in there to remove the water. Maybe some got in the dist too? I saw the post about the vac advance

How did that rebuilt vac advance turn out?? You said above its running great so I assume they did a pretty good job. Glad its running for you again.