Accelaration problem with Carb?
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New User
Joined: Mar 2004
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From: Seattle
Accelaration problem with Carb?
Need some help. 72 Ford F-250, 360 engine, 2 barrel carb.
When I step on the gas pedal, there is a huge heisitation and then the idal will slow almost to a stop and then go real high and the truck is almost jerking.
When I push the accelarator looking at the carb with the hood up I hear a gasp of like air in all the heisatations.
If I drive the truck, it is backfiring like crazy with real loud booms.
I thought I got bad gas, but now I am thinking the problem might be bigger. Any ideas or suggestions?
When I step on the gas pedal, there is a huge heisitation and then the idal will slow almost to a stop and then go real high and the truck is almost jerking.
When I push the accelarator looking at the carb with the hood up I hear a gasp of like air in all the heisatations.
If I drive the truck, it is backfiring like crazy with real loud booms.
I thought I got bad gas, but now I am thinking the problem might be bigger. Any ideas or suggestions?
Post Fiend
Joined: Sep 2004
Posts: 5,231
Likes: 1
From: Near Fresno, California
Do you get a squirt of gas in the throat of the carb when you mash down on the gas? If not, look at your accelerator pump on the carb.
Also check to see if the vacuum advance line is connected - you distributor should retard the timing when you step on it.
Also check to see if the vacuum advance line is connected - you distributor should retard the timing when you step on it.
Post Fiend
Joined: Sep 2004
Posts: 5,231
Likes: 1
From: Near Fresno, California
Bad/dirty gas could have plugged the passage in your carb - but your problem is that it is not getting that shot of gas when you step on it. A carb rebuild will fix it. Like qman said, just replacing the accelerator pump may be all you need, if you do not want to do a full rebuild on your carb.
Post Fiend
Joined: Sep 2004
Posts: 5,231
Likes: 1
From: Near Fresno, California
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New User
Joined: Apr 2004
Posts: 14
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From: Bothell, WA
Make sure if you rebuild the carb to take your time setting the float as this is probably the most importatn part of the rebuild. replacing the accelerator pump is easier than a complete rebuild and shouldnt take too long if you want to try that first.
On some carbs you can adjust the accelerator pump as well in a few places 1) a high or low pin, although if it was ruinning good before this prob isnt required 2) a ddouble pumper" has a screw you can adjust, but these are fine details. If your truck was runinng good before and then isnt now, prob a bad carb or accelerator pump, as the fellas sugested.
Get a good rebuild kit - autozone.
On some carbs you can adjust the accelerator pump as well in a few places 1) a high or low pin, although if it was ruinning good before this prob isnt required 2) a ddouble pumper" has a screw you can adjust, but these are fine details. If your truck was runinng good before and then isnt now, prob a bad carb or accelerator pump, as the fellas sugested.
Get a good rebuild kit - autozone.
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From: **** hole San Jose ca.
1. Your problem may only be the vacuum pot that pulls the choke butterfly open when the engine starts. It has 3 small screws holding the cover on and is on the top of the carb. "To check" pull air cleaner, start engine see if vacuum pot linkage arm should be pulled down. if good.
2. The accelerator pump maybe work fine, but the pump shot check valve maybe bad. Your's should be a little round redish color rubber thing inside the accelerator pump housing it's head is about 3/8'' size. This stops your pump shot from going back in the float bowl & pushes it throught your pump shot nozzles.This is where you should see gas shooting out looking down the carb
To replace it, remove old one. New one has about 1/4'' long rubber pulling stem that you pull from the float bowl side. Older model carbs have a check-Ball. ps good or bad the accelerator pump or check valve will not make any air noises."Warning" this can be very (dangerous) if your not very CAREFUL Get a can of quick start and lightly spray around manifold edges,carb base, vacuum hoses checking for vacuum leaks. Engine will race if you find a intake leak.
my 2cent
orich
2. The accelerator pump maybe work fine, but the pump shot check valve maybe bad. Your's should be a little round redish color rubber thing inside the accelerator pump housing it's head is about 3/8'' size. This stops your pump shot from going back in the float bowl & pushes it throught your pump shot nozzles.This is where you should see gas shooting out looking down the carb
To replace it, remove old one. New one has about 1/4'' long rubber pulling stem that you pull from the float bowl side. Older model carbs have a check-Ball. ps good or bad the accelerator pump or check valve will not make any air noises."Warning" this can be very (dangerous) if your not very CAREFUL Get a can of quick start and lightly spray around manifold edges,carb base, vacuum hoses checking for vacuum leaks. Engine will race if you find a intake leak.
my 2cent orich
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