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Username Post: symptoms of bad accelerator pump        (Topic#57205)
chevy4ever 
Senior Member
Posts: 863

Age: 31
Loc: Virginia Beach, VA
Reg: 08-31-03
02-09-04 05:51 AM - Post#388767    

what are the symptoms of an accelerator pump going bad. Ive got a 4bbl carter 625cfm. My current symptoms are; It tries to stall when you give it only a tiny bit of gas, Im talking just barely over idle, like what you would give when easing into a parking spot or leaving a stoplight. But if you push a little harder its ok. Its not a real big deal but i usually dont accelerate fast on a normal basis so its annoying to have to mash it each time to avoid the stumbles. Incidently it idels smooth, it is just at that point a few 100 rpm above idle (currently 5-600 in drive)

My friends truck did sort of the same thing when his acc. pump went bad. What do you guys think? Thanks All!!
A stranger is just a friend you haven't met yet
Uncle Jesse Dukes of Hazzard

1966 C10 LB Fleetside
1986 GMC SWB 2WD 5 inch lift 33" tires 4.10 gears with locker
2006 Trailblazer 2WD


 
BrianEsser 
BANNED
Posts: 7383

Age: 38
Loc: North Star, Ohio
Reg: 06-30-01
Re: symptoms of bad accelerator pump
02-09-04 05:59 AM - Post#388768    
    In response to chevy4ever

Most times mine were bad. It would fall flat on it's face under hard acceleration and would do ok if you babied it.


 
chevy4ever 
Senior Member
Posts: 863

Age: 31
Loc: Virginia Beach, VA
Reg: 08-31-03
Re: symptoms of bad accelerator pump
02-09-04 06:01 AM - Post#388769    
    In response to BrianEsser

The only times mine falters under hard acceleration is when it hasnt fully warmed up yet and it sorta backfires thru the carb. Once warmed, it has no problems.
A stranger is just a friend you haven't met yet
Uncle Jesse Dukes of Hazzard

1966 C10 LB Fleetside
1986 GMC SWB 2WD 5 inch lift 33" tires 4.10 gears with locker
2006 Trailblazer 2WD


 
Jay727 
Old as Dirt Member
Posts: 5968

Reg: 09-02-01
Re: symptoms of bad accelerator pump
02-09-04 06:26 AM - Post#388770    
    In response to chevy4ever

It sounds like you may need to adjust the mixture screws a little richer.
I had the problem with an edelbrock carb, the mixture screws had an effect even up to cruise speed.
I adjusted it out once, then when the weather changed I had to readjust it because the symtoms came back.

 
0utlaw 
Very Senior Member
Posts: 2043

Loc: New Hampshire or Florida
Reg: 09-10-02
Re: symptoms of bad accelerator pump
02-09-04 06:41 AM - Post#388771    
    In response to chevy4ever

Look down your carb (wear safety glasses) with the engine off and manually ease on the throttle. If the pump is bad, gas won't squirt out in good supply.
The clue about checking your idle mix is a good one as weather is always changing.
Also, a spark that is retarded more than it should be, will cause stumbling/ sometimes stalling also.... making a weak pump more noticeable.. For instance, if you have it on 4 BTC and it will take 10, the engine will really respond to the highest advanced/ no ping setting. A bad vacuum can sometimes causes stumbling.
I'm the master of MOUSE...you got any duck tape?


 
Robert_May 
Old as Dirt Member
Posts: 6939

Loc: San Marcos, CA USA
Reg: 01-03-02
Re: symptoms of bad accelerator pump
02-09-04 11:18 AM - Post#388772    
    In response to chevy4ever

Since you are not running lean when you give a good push on the gas pedal, it isn't the accel. pump. I'd richen up the idle jets a little and see if that fixes the problem. The idle circuits actually are still providing fuel even at a crusing speed of 2K rpm and that will make a difference in the little bit of additional need for air needed for a gentle acceleration. You may also want to check the float level to make sure that it isn't too low as this will slow down the gas to the main circuits.
Most accel. pumps are setup with a leaking circuit so that a gentle movement doesn't dribble gas into the carb all of the time and thus you shouldn't be getting a squirt from the accel. pump holes with that gentle push.
Robert May Fat? Eat less and you will get thinner!


 
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