Stall, Backfire

[74se]

I have a stock 318 2blr carb. When accelerating i get a stall, hesitation and bit of a backfire thru the carb. Am i running to rich? How can i adjust it in?

[DynoDave]

Severe hesitation, just off idle?

[Deleted]

A severe hesitation along with backfire thru carb would have me looking at the timing first.
How many miles on the engine? Timing chain might have jumped.

Backfire thru carb is generally a lean condition issue. Another thing to look at is the accelerator pump shot.

[Deleted]

Aug 10, 2015 20:17:25 GMT -5 @tom said:

A severe hesitation along with backfire thru carb would have me looking at the timing first.
How many miles on the engine? Timing chain might have jumped.

Backfire thru carb is generally a lean condition issue. Another thing to look at is the accelerator pump shot.

[Deleted]

After thinking about this for a little while....I have a few more questions.

What is the history of the car?
Has it been sitting up for a long time?
Has it ever ran well as long as you have owned it?
Do you know how many miles are on the engine?

In a previous post, you seemed interested in rebuilding the engine.....
So, I am thinking it might possibly be best to start with the basic starting point....and recommend a compression test first.

[DynoDave]

Aug 10, 2015 20:17:25 GMT -5 @tom said:

Another thing to look at is the accelerator pump shot.

That's where I was going...thinking if it was a sever stumble off idle, then it's likely the accel. pump.

[Deleted]

Aug 11, 2015 7:51:15 GMT -5 DynoDave said:

...thinking if it was a sever stumble off idle, then it's likely the accel. pump.

Yeah...that is something that I need to look at on my own car.

I really don't like working on carburetors.....so I have lived with the stumble up to now.
One of these days, maybe I will get motivated to check it out more.

[74se]

The engine is not the original. It is out of a 71. (Cast#s show that ) rebuilt carb from napa. It hesitates when the pedal is pushed down.

[Deleted]

Aug 11, 2015 12:32:59 GMT -5 74se said:

The engine is not the original. It is out of a 71. (Cast#s show that ) rebuilt carb from napa. It hesitates when the pedal is pushed down.

The out of the box rebuilt carbs from the local parts stores are very questionable.
Have you performed a vacuum check? Are the plugs black?

Bob

[Deleted]

Aug 11, 2015 12:32:59 GMT -5 74se said:

The engine is not the original. It is out of a 71.

Ok...how about all the other questions I asked?
The more information you provide, the better advice we can give.

For example....
If the car has been sitting up a long time...fuel quality and fuel delivery would have to be considered suspect.
If you have never had it running well, a compression check could be in order to verify the basic mechanical condition of the engine.


Back in my beginning days of turning wrenches, we had an old dinosaur of a diagnostic machine we had to use on all engine diagnostic work.
If we wanted to get paid for our diagnosis, we had to run it thru all the tests and print out the results.
We all hated it! It seemed so tedious to do all that work before really getting into the real meat of the diagnostics...checking codes, looking at data, etc etc
But in hindsight...it was a great tool. One of the first tests was a relative compression check.
No sense in replacing plugs, wires, etc etc...... on car with a basic compression issue.
Years later, when we no longer required to use the dinosaur... it was surprising (or not) how many misdiagnosis's were made because someone overlooked the very basics.