Carb issues

[CherryK5]

Does anyone know how to keep my truck from wanting to die everytime i hit the gas? I have to double tap the gas pedal and sometimes triple. If i dont it just dies. I've raised the idle but it still tries to die unless it idles around 1800rpm, which is wayyy too high. My truck has always done this and it pisses me off. Any ideas on how to fix it?

Edit: Im running an edelbrock performer 650 with 750 secondaries on a 355 GM performance crate motor.

 

[NorCal_Chris]

any vacuum issues?

maybe accelerator pump?

 

[Fordum]

Most likely? Accelerator pump bad.

Next? tossup between float level way too low, but should cause other problems, or secondaries set up wrong and trying to open too quick.

 

[chalet2506]

run a can of carb cleaner through. cheap, and can't hurt.

 

[xXamwxxXx]

Well I was having this same problem a while back. New fuel filter, carb cleaner and I leaned out the mix a bit and it runs good now (just make sure to keep track of your adjustments.) I believe it was stumbling on acceleration due to it getting too much fuel and not enough air, when it was going at higher speeds it was fine. Basically just took a flathead and drove around for a few weeks til I got it right. Not the proper way to go about it but its cheap and easy.

 

[CherryK5]

run a can of carb cleaner through. cheap, and can't hurt.

Haha. pulled it apart and soaked it 2 days ago.

And about the pump... Its new, but the tunnel or whatever is clogged somehow. i tried everything to clear it out but nothing worked. And that would make it flood even worse if it worked.

 

[Fordum]

Haha. pulled it apart and soaked it 2 days ago.

And about the pump... Its new, but the tunnel or whatever is clogged somehow. i tried everything to clear it out but nothing worked. And that would make it flood even worse if it worked.

Why do we think its flooding?

Carbs work off the venturi effect when air rushing past a hole or tube causes a vacuum that sucks the gas out and mixes it with the air. The faster the air goes by, the more suction.
When you open the throttle more, the air slows down because the space it has to go through is now suddenly wider.
And the engine has not had time to get faster, so it is still sucking the same amount of air through a wider hole.

This causes more air into the engine, and much less gas. So, instant stall.

The accelerator pump shoots a shot of gas directly into the intake when you press on the throttle to make up for the loss of vacuum. It sounds like yours is not doing that, so it stalls out.

It only pumps that gas in when you increase the throttle, so it would have little effect on flooding.

J.

 

[USSkoval]

When you pump the gas (not running), does fuel squirt?

 

[diesel4me]

Might be a big help to know WHAT carb we're fixing here.....but good general advice by all ..

It could have clogged accelerator pump passages,or some carbs used a spring and steel check ball valve in the pump discharge jet,on many GM's they get pitted or dirty and the ball cant seal well and the pump loses its prime and wont squirt sufficient gas during acceleration..if it uses a accelerator pump diaphram it might be defective or leaky,or the stroke of the pump might be too short,the pump cup worn,etc..

Vacuum leaks at any hose like the PCV or power brakes,carb base gasket and intake can affect "take offs" more than idle or driveability sometimes..the secondaries on 4 barrels can stick open or open too soon and cause a bog,many times I have found vehicles with a bog or stumble on acceleration did not have any carb issues,it turned out to be vacuum leaks,bad vacuum advance unit on the distributor,late timing,bad plugs or wires that "snuff out" under a load,once I had an ignition coil with a crack let the spark leap to the small terminals (12V) to the high tention lead ,only when under acceleration..had defective ignition modules that crap out only under a load like take offs and had no dwell advance do it too..with points,bad bushings in the distributor shaft can cause a hesitation ..

I agree a hesitation on take offs IS a very annoying and one of the most dangerous things to have to put up with in city traffic..sometimes you cant afford to let it take its sweet time getting out there when entering an intersection or freeway..

 

[NorCal_Chris]

Does anyone know how to keep my truck from wanting to die everytime i hit the gas? I have to double tap the gas pedal and sometimes triple. If i dont it just dies. I've raised the idle but it still tries to die unless it idles around 1800rpm, which is wayyy too high. My truck has always done this and it pisses me off. Any ideas on how to fix it?

Edit: Im running an edelbrock performer 650 with 750 secondaries on a 355 GM performance crate motor.

this has been here since yesterday

 

[zombie1969]

Hes saying haha when his engin is falling on its face and already knows the accelorator pump isnt working thinking it flooding.Whats a 650 with 750 secondaries?Custom job or something?Never herd of it although I havent bought a new carb in over 10 years.

 

[Burbdood 74]

How long have you had this carb on your truck? Have you messed with the rods and springs at all? I'm running an Edelbrock 1406, (600cfm), on my 72 Pontiac and I had to try 3 different spring and rod combo's before I got it running smooth as silk. The weaker springs could be just what you need to eliminate that hesitation.

Just a thought, but check to see if your distributor is advancing correctly while you have someone run up the throttle. I've seen a couple of cases where the vacuum advance canister was sticking just a little bit and the timing wasn't advancing smoothly when they hit the gas.

 

[CherryK5]

Hes saying haha when his engin is falling on its face and already knows the accelorator pump isnt working thinking it flooding.Whats a 650 with 750 secondaries?Custom job or something?Never herd of it although I havent bought a new carb in over 10 years.

Haha, yea custom job. I had the 750 laying around and thought it would be cool, turns out its ****ing awesome when you stomp on it.

And thanks everyone for the advice, for the most part it sounds like my accelerator pump is the culprit, i just assumed it was flooding out when i hit the gas but its been doing the opposite (go figure) I'll have to get the gunk out of the accelerator tunnel. The carb sat for a while and that was the only thing that didn't end up spotless after i cleaned it up.