Bogging down when accelerating

[cptita]

Help, my car won't go! I'm running a totally stock 302-2v and I just had the carb rebuilt. It fires up and idles great and when I rev the engine, it seems fine. It seems good when I put it in gear, but when I hit the gas it wants to stall. It sputters and hesitates until I let up on the gas. Funny thing is, it doesn't always do it. Sometimes it accelerates fine, sometimes just a little hesitation, and sometimes I can't go more than 5mph down the street.

Any ideas on what could be going on?

 

[Mikes73]

It sounds like your accelerator pump on the carb is not working correctly.Remove the air cleaner and with the engine off manually open the carburetor while looking down the throat and see if you are getting two shots of fuel (one from each side) while the butterfly opens up. Post you results.

 

[Jeff73Mach1]

Also look for a vacuum leak or a shot PCV valve (creating a vacuum leak)

Another thing to check is the condition of your ignition system-bad wires or any other component can cause weak ignition that works fine when the engine isn't under a load, but when it is everything goes to hell.

Intermittent problems are a bear. I would check all the grounds while I was at it.

 

[Don C]

Intermittent problems are a bear.

+1

Mike and Jeff both have possible solutions. Something as easily overlooked as a loose (or missing) breaker plate ground or a loose or bad condenser can cause your problems. Debri floating around in the gas tank can plug the inlet. Pick one system and go through it trying to find a problem, try it to see if you still have the problem and if so go onto the next.

Good luck...

 

[cptita]

I'm definitely getting 2 shots of fuel when I manually open up the carb. Does this mean I can rule out the accelerator pump being the problem? Also, my plugs and wires look like they're in good shape, but they are probably 10 years old.

 

[piper62j]

If all else checks out, all that's left is the power circuit in the carburetor.. What was the reason for the carb rebuild in the first place? If the problem existed prior to the carb rebuild, you must look elsewhere.. We need more information to come up with some solutions..

 

[cptita]

A little background...I had the car in storage while I was building a garage for it. When I took it out of storage, I had trouble getting it to drive on the trailer. It stalled every time I hit the gas. I assumed it was bad gas or something gummed up the carb. So I installed a new tank, new fuel pump, and had the carb rebuilt. I thought that did the trick, but occasionally it still happens. As you can imagine, it makes me nervous driving it because I never know if I'm gonna have to limp home...

 

[Mikes73]

How's the ignition timing? is it set around 10* btdc? For the time being you may try unhooking the vacuum advance until you get things sorted out to see if things improve.

 

[piper62j]

Glad you mentioned the car was in storage.. Also helps to know the fuel tank and fuel was replaced.. I'm leaning towards fuel pump failure.. Can you take a pressure reading on it. Off hand, I don't know what the specs are, but something like 5 - 12 psi might be in the ball park..

A gear head friend of mine and I were driving our cars to the car show last summer and his just quit running.. We disconnected the fuel line on the side of the road and cranked the engine over.. Barely any fuel was being pumped up to the carb.. Replaced the pump and all was well..

Just a thought..