I have a bog/hesitation problem that occurs when i acccelerate from idle. I just recently noticed this happening and it only occurs when I press the gas hard enough to open the secondaries from a stop. The problem doesnt exist when I accelerate normally. I also dont have the problem when I accelerate from cruising. I checked, and the secondaries seem to open freely whithout any resistance. Could this be a bad accelerator pump? BTW the engine is a mild 403 with a 72 quadrajet.

 

Secondaries opening to soon, ether the pull off is bad or someone adjusted the flapper to SOFT. Check pull off first.

 

it could be a LOT of things... including ignition timing


bill

 

Choke pulloff, RH side, connected to secondary air valve by means of a link?

It holds vacuum ok and has a good hose?

 

Tested the pull off and it seems to be working fine. It holds vacuum and the link is connected to the secondaries. The problem is most noticeable at WOT but still happens most every time I get on it hard from a stop.

 

No expert but start with the basics. Make sure it's in proper tune first. Carbs get blamed for everything.

With the engine off, look down the cab to see if the pump gives 2 solid squirt of gas when you pull the throttle cable.

After that. see if the secondary springs are too loose. Google how to adjust a quadrajet bog.

 

I checked and there are two steady streams of gas when i hit the throttle. I will try adjusting the secondary springs and see if that fixes the problem.

 

Accelerator pump! I had the same issue. A good rebuild kit and forty minutes on the bench rebuilding the carb should solve the problem.

 

there is a spec. for adjusting the vacuum break link for the air valve dashpot adjustment. if somebody has been bending on that link, or replaced the vacuum break, the link spec. will need to be checked/adjusted. the link controls how far the secondary air valves open before the vacuum break can release. if you look at the front side of the air horn casting for the secondaries, just above the front edge of each air valve, you will see a small hole. these are the secondary accelerator discharge ports. they need to to be partially covered when the vacuum break is active while lightly opening the secondary air valves. if you give me a carb. number, i can give you the spec. another thing to keep in mind, the secondary accelerator well tubes often fall out of the air horn casting over time. this can also cause your problem. if these tubes are missing, they can't carry fuel up to the secondary accelerator discharge ports.


bill

 

Thanks, i should be able to get you the carb number tomorrow. Also if the secondary accelerator tubes did come out, how difficult of a fix would that be for someone who doesnt know much about carbs?

 

the fix is simple, getting the carb. apart and back together is the hurdle you'll have to overcome.


bill

 

cheap broken practice carb is a good idea for a beginner to dismantle

 

Carb number is: 7042250