Fuel Dumping Inside Carb After Shut-Off

F

Fairlane Fixer

Well-known member
Had an old Holley 1bbl that was acting up on idle and acceleration.

Bought a rebuilt Autolite 1100 (original for my vehicle)
Set throttle linkage, Choke setting (manual choke), Dashpot,
and check float level (ok).
After installation and idle for a few minutes to begin mixture
adjustments, I shut off the car and gas was pouring into my
vent opening. I doubled checked float and needle and is OK.

Put back on old holley, since it never flooded like that.
And now it is flooding.

Could I have begun to have too much fuel pressure (stock fuel pump)
all along that was causing my old Holley to act up in the 1st place and
was just getting worse?

Would a bad fuel pump cas too much pressure?
The Holley never flooded in the year since I had the car.

SORRY SO LONG?

Any and all help is desperately needed and appreciated.
 
Never heard of a mechanical pump increasing pressure with age.

Check your engine temp. Is this happening right after the engine is shut down? Could be that the heat from the block is expanding the fuel already in the bowl causing the overflow.

I would try the simplest solution first and add a Phenallic sheet spacer between the carb and the spacer. Keep that heat from transferring from the intake to the carb.

Good luck, Ric.
 
Is the float or needle sticking open? I have had that happen a few times after installing a carb.
Doug
 
What Fastback said:
some carbs are easily screwed up by trash. In the motorcycle word Mikuni's are notorious for this happening. Usually a tiny piece of trash gets between the float needle and the seat. This causes the bowl to overfill. If you have any rubber line that you removed and replaced i would look here first as often a tiny fleck of rubber will be the culprit. If all hard line, a flake of thread or dirt will get in there. Sometimes rapping the carb where the gas line comes in (wood or rubber screw driver handle) will dislodge it and it will work fine. of course then there is the possibility of that same trash getting in the jet and clogging it making you go lean later.
 
Is your fuel filter on the carb itself? The simple process of screwing a metal filter on can cause metal filings to be worked loose which can clog the needle and seat.

Or pushing fuel lines into rubber gas hoses can scrape off enough rubber to clog thing up. Is there any rubber hose between your fuel filter and carb?

Cheers,
Steve-O
 
I've been running an older Holley 1904 now for
a couple of weeks without flooding problems.

I just wished I could solve the Autolite flood problem.
I re-installed it the other day to see what happens and
it still yet flooded.

Also cannot seem to get the mixture set. Screw is all
the way in. If I back it out, it is worse.

I even double checked float level and even raised the
level a bit thinking less fuel in the bowl may help.
But no, it still floods.

I don't think heat is an issue.
Timing is OK, (other carb runs good & no pinging)
Fuel is clean.

Any ideas? Carb was reman. recently through a
repitable company.

Thanks
 
Fairlane Fixer":1jqcd4r7 said:
I even double checked float level and even raised the
level a bit thinking less fuel in the bowl may help.
But no, it still floods.

I don't think heat is an issue.
Timing is OK, (other carb runs good & no pinging)
Fuel is clean.

Any ideas? Carb was reman. recently through a
repitable company.

Thanks
Click to expand...

HI
If heat isn't an issue then it has to be float or needle and seat prob..
When you said you raised the level you did mean with it inverted right? and did you bend it in the right place so it shuts off sooner? When you bent it the pad where the needle sits should not have moved just the float its self? Or to better put it the pad where the needle sits should be farther from the float than it was. I don't have any pic to show what I mean.. but if fuel is comming out of the vent tube there's too much fuel in the bowl.
with the float out the bowl should only be about 1/3 or 1/2 full.
Tim
 
Yes it was inverted and float adjusted higher up where
needle would close sooner.

I even removed needle to see if it was distorted.

Maybe I should get carb cleaner, clean it good inside, &
blow it out with air at all orfices.
 
Howdy Fairlane Fixer and All:

Two thoughts- make sure the needle valve seat is screwed into the carb body tightly. Make sure the needle is lined up with the seat as it hangs on the wire.

Make sure that the gasket does not interfer with the movement of the float and armature. If it does, it will not allow the float to rise and the needle to seat,

Even though you feel the rebuilder is reputable, it is not unlikely that you go a problem carb. Given that it requires that the idle air screw is all the way in causes me to think more is wrong with this carb than just a stuck needle seat.

Adios, David
 
they they said sounds like needle and seat problem... it happens to me all the time. :wink:
 
HI
I all most have to agree with David (CZLN6) with the mixture screw all the way in it should die .... sounds like a vacuum leak maybe as well are the gaskets right..
tim
 
When you said the float level and valve were all set properly, I was suspecting that the throttle plates could be open too much. That would help explain why the fuel mixture screw would not have any effect if the carb was transitioning to the intermediate fuel circuit. But it does not explain the fuel flow after the engine is shut off. So I keep coming back to the fuel float level, needle and seat or some plugged orifices to explain the fuel flow.
Doug
 
if the fuel is overflowing into the venturi it makes sense that it would run better with the mix screw all the way in--as it is getting raw gas anyways. If gas is overflowing into the carb throat it pretty much has to have a float needle related problem. or something is cracked--i mean if the gas won't stop flowing then what else could it be. With the carb off and the top removed you should be able to simply blow theough the inlet and raise the float with your hand and feel the valve close. Might not taste too good but mechanics usually have poor taste anyways.
 
Fairlane Fixer, on the top, underside of your 1100, are there little mounts spaced about 1" appart? The reason I ask is you may be missing a small plate for the vent. I had the same problem with my '63 several years ago & it drove me nuts as I couldn't figure out what the problem was. Then, I noticed a little plate at the bottom of the float bowl. Once I re-installed it the car ran fine. I'm not all that sure exactly how to describe it, but I can take pictures for you if you want.
Edwin
 
I like my glass bowl on my Holley for problems like this one. I had rusty lines that caused mine to overflow (before I got a glass bowl). I've got a rubber line now from the pump to the carb. Other issues have parked it for now.
 
I'm kind of at a loss :?: :?:
I guess contenu to adjust the float untill there is NO fuel comming in and then go back from there also check like czln6 suggested as to making sure the needle seat it tightly screwed into the housing..
It has to be something wrong with float, needle or the seat thats what stops the fuel from comming in..
Tim
 
I guess I could start with very little fuel coming in and gradually work
up. If I get it to work with inadequate fuel, will it not try to stall
on turns?

Is there supposed to be a plastic type insert in the throttle neck
that form the shape and size of the opening?
 
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