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Hesitation under acceleration

D

David67

Active Member
While driving home the other day, I noticed that my car was hesitating when I was accelerating. When I got home, I took off the air cleaner and then sprayed some carb cleaner and it went away. Today I was driving around and it did the same thing. So I did the same thing and sprayed some carb cleaner and it away. The carb was looking like it needed to be rebuilt, which I did 2 years ago. The carb looks really dirty. It's a edelbrock 1406 carb.

Over the last few months I changed the spark plugs, fuel filter, spark plug wires still look great. I have a pertronix billet distributor and the cap and rotor look fine.

So should I look at anything else or just rebuild the carb?

Thanks
 
I would do the carb since it is easy and low cost to do. That way you eliminate it from the problem list if the miss continues.
 
So I had the carb rebuilt today. I installed it and it ran fine until after I ran it to go get dinner about 5 miles away. On the way back it would hesitate all the time. I installed a clear fuel filter and the fuel looks clean. Do you think I just bad gas, maybe a bad fuel pump?? Should I looked at ignition system? I'll check the spark plugs tomorrow.
 
Pertronix is normally good or bad...no in between.

How old is the gas? Sometimes the treatments like sea foam can cause a miss/stutter if it is used at a higher mix level. Might even run a pint of fuel into a clear jar and see what it looks like. Just use the fuel pump but be careful of spills and such.

When it is hesitating, you might try putting it in neutral, shut the key off, and check the fuel level in the carb bowl. This should be done without letting the car idle at all...want to see the carb fuel level as close to running as possible.

If the fuel pump very old, it could be weak...thus not providing enough fuel to maintain a mooth engine.

Will it do it sitting in the driveway? If so, you can check all the plug wires for spark with a timing light.

If you see any black smoke from the pipes, that would be a rich issue....

Just some thoughts to look at....
 
The gas is about a 6 days old. I had let it get a little lower than I usually do.

I have never used seafoam on this car before. I have a clear fuel filter so I can inside and I the gas looks good.

It does do it in the driveway at idle, so I'll check the wires with a timing light tomorrow and report back.

No black smoke at all out of the exhaust.

I'll check back later today with an update. How do you know if you have a bad fuel pump? I have feeling that's my problem.

Thanks for your help again.


Sent from my SCH-I535 using Tapatalk 4
 
You can remove the fuel line, put it in a gallon jug and have someone crank the car over (do not let it start) and measure how much fuel comes out in a minute (or whatever time frame you want). Extrapolate that out to GPH and see if it matches the stated flow of the pump.
 
Stop and retrace your own steps. It would seem you are getting ahead of yourself. Ask yourself a couple questions.

1. When you sprayed the cleaner in the carb did it really "fix" the issue? Did you drive the car around for a while and notice the problem was gone?

2. Did the second time you used the cleaner have the same results?

If all of the above are true, why would you blame anything other than the carb? If you drove the car even a bit after spraying and the issue was fixed very hard to point at the fuel pump. No? A mechanical pump is going to be very consistent in performance good or bad. It's not going to "come and go".

Just because you paid someone to "rebuild" the carb doesn't mean they fixed the issue with the carb. Take the car back to the tech and tell/show him the problem. I'm betting letting him experience it will help him to diagnose it quite quickly.

As an old field tech, just seemed to me that you might be getting ahead of yourself in your troubleshooting.
 
Yeah I have been thinking about it while at work. On the drive to work it started maybe a mile into my drive. Got to work and looked at the fuel pump and it's fine. The fuel filter looked completely full. The carb guy said the carb was full of gunk and smelled liked bad gas.

Since I filled the tank last Thursday with 91 octane. He said I need to blow out the fuel line.

I'm going to check the ask the spark plugs when get off. I installed them new about a month ago. Maybe I had one go bad. I also check the spark plug wires to see if I need new ones.

If I can't see a problem today I'll go back to the carb guy to have him look at it tomorrow. He's about 7 miles away maybe he'll give an idea what could be wrong.

Sent from my SCH-I535 using Tapatalk 4
 
I wonder if the problem is due to rust getting past the fuel filter.
 
Could even be bad gas? It does happen. Though I'm not sure how that fits with everything you've told us here.
 
"Midlife" said:
I wonder if the problem is due to rust getting past the fuel filter.
Click to expand...

+1

Had a small pc of debris get by the filter and partially clogged one of the jets. Took forever to find that!
 
UPDATE!!!

Well I figured it out. I was my stupid ignition wire that was coming from the firewall to the positive side of the coil. I started to check those wires with the car and suddenly it smoothed out. So I cut the wire back far enough to were it shorted at and connected a new wire. I am going to my local mustangs parts store tomorrow morning to get a new harness.

What was funny before I figured it out. I looked up in my garage and saw my Johnpro head on a stick. I was thinking what would Johnpro do? I figured it out about 2 minutes later. Thanks Johnpro!!!

Rebuilt the carb, new cap and rotor and bought some new spark plugs wires. Damn oh well.

I am telling myself that I really need to buy the new cap and rotor and rebuild the carb. That was money well spent. :thum
 
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