This might be a strange question, or just a strange problem. EXCESSIVE fuel pressure.

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Lester
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#1
This might be a strange question, or just a strange problem. EXCESSIVE fuel pressure. 226 engine, stock dual action fuel pump. Pushes engough pressure I have fuel spewing out of cab vent within 45 seconds of starting it. Brand NEW carb as well as the original. What can cause this? It runs smooth as silk with the new carb, until this happens and floods it.
 
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Lester
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#3
doubt it....first carb I knew for sure it wasn't sticking, second does same thing, I void the carb warranty if I crack it open. and when it it spews fuel, I mean it SPEWS fuel.....not seeps fuel.
 
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Lester
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#4
Missed a sheet that came with the carb, Which is one of those universal ones you see. It says one of the causes of flooding can be a worn out fuel pump. Fuel is clean and it its through a new filter so crud isn't an option, Didn't smack the carb because the old worn out one did it too. Only it ran rough as hell with it.
 

Moriazbane

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#5
I bought 2 of those brand new made in india carbs from a well known vendor with the adapter to make the air cleaner fit and the base spacer that adapts it to the manifold and makes it the correct height. I then bought a fuel pressure regulator to adjust the pressure to about 2.5 lbs. Nothing will make those carbs work. They will be fine a week or two and then dump it all over the place. I finally bought a used Jeep carb off ebay and never had another problem. I sold one on ebay saying it was new but flooded. (I modified it with 2 rivets because the interference fit air cleaner adapter kept coming loose and figured they wouldn't take it back, the other is sitting in a box because I used the carb spacer off the bottom on my incorrect for the year intake) a waste of close to $300. Buy the original Willys. That is what worked for me.
 

Blindmelon

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#6
Put a gauge on the fuel line and crank the engine... It should show at least 3 psi and less than 6 psi.. The carb needle and seat will handle
this pressure fine.. Fuel pressure on diaphragm automotive fuel pumps is determined by the diaphragm spring and is non adjustable..
But can be fiddled with... I've never tried connecting fuel lines to the vacuum ports.. And I wonder if that's what's going on..
 

Moriazbane

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#7
If you do buy a regulator, be aware that the Holley Regulators and most others will NOT work. They aren't fine tunable to the low pressures we need. They are for High performance racers with high consumption engines. Mine was made for small displacement British cars with low pressure and is adjustable in half lbs to 5 lb. max. I tried my flathead at 1.5 on up, and it had no noticeable starvation at 2. I gave it another half, but your 6 could need more. I think it depends on the carb more than the displacement though.
 
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#8
Vacuum port in the bottom and fuel is on top? Correct? At least that's how mine is hooked up. I need to look for my pressure gauge. I have to old very crusty "spares" one of which is an AC, and different than the other, I assume both of those need rebuilt at the very least. There is one in Manassas at Autozone, but no way can I get there because of the extreme traffic between Arlington and there after work. And don't want to risk a quick delivery to home and find out its not the right one.....because their search listing is a bit weird.
 

cwdtmmrs

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#9
Put a gauge on the fuel line and crank the engine... It should show at least 3 psi and less than 6 psi.. The carb needle and seat will handle
this pressure fine.. Fuel pressure on diaphragm automotive fuel pumps is determined by the diaphragm spring and is non adjustable..
But can be fiddled with... I've never tried connecting fuel lines to the vacuum ports.. And I wonder if that's what's going on..
I agree, except I would go less than 4 psi. If you still have fuel spewing out of the vent, the needle is not seating.
 

jfcroni

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#11
Other less common things to check: Is there any possibility your tank (if un-vented) is getting pressurized (can happen but not in 45 seconds), fuel line or filter is too close to heat expanding the gas and affecting pressure. (but wouldn't happen in 45 seconds either).

Other than that if pump PSI is good... and carb is still spewing while running, then it sure seems like the needle isn't holding or there's a gas-filled or defective float... or there's some gasket failure.. or like others have said - just a bad carb unit.

Don't discount the possibility that the part may have been dropped in shipment. It would be possible to affect the float adjustment if it were dropped. Also, check to be sure you didn't receive someones returned inventory. Just want to be sure no one else owned the carb and messed with it before you got it.
 

steve.bright

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#12
I believe you have the fuel pump hooked up wrong. Vacuum is on top, fuel on the bottom. That's the way it is on my 56. others should be able to verify this before you spend any more money.

Good luck
Steve
 

captainlance

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#13
Vacuum port in the bottom and fuel is on top? Correct? At least that's how mine is hooked up. I need to look for my pressure gauge. I have to old very crusty "spares" one of which is an AC, and different than the other, I assume both of those need rebuilt at the very least. There is one in Manassas at Autozone, but no way can I get there because of the extreme traffic between Arlington and there after work. And don't want to risk a quick delivery to home and find out its not the right one.....because their search listing is a bit weird.
The original carter type dual action fuel pumps are gas on bottom, vacuum section is on top. This also goes for the Airtex and other after market replacement pumps.
 
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#14
Hmm....I put a gauge on this. before reading your responses..and I'm pumping something north of 15psi fuel pressure. I say something because my vacuum/fuel pressure meter pegs at +15psi and it was pegged. Guess I need to move those. Thats how it was when I got it.
 
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#15
Other less common things to check: Is there any possibility your tank (if un-vented) is getting pressurized (can happen but not in 45 seconds), fuel line or filter is too close to heat expanding the gas and affecting pressure. (but wouldn't happen in 45 seconds either).

Other than that if pump PSI is good... and carb is still spewing while running, then it sure seems like the needle isn't holding or there's a gas-filled or defective float... or there's some gasket failure.. or like others have said - just a bad carb unit.

Don't discount the possibility that the part may have been dropped in shipment. It would be possible to affect the float adjustment if it were dropped. Also, check to be sure you didn't receive someones returned inventory. Just want to be sure no one else owned the carb and messed with it before you got it.
It was sealed in plastic shrink wrap. Everything was sealed up in their respective packages. It was pulling from a 5 gallon gas can, was pushing MORE than 15psi fuel pressure, and as some other guys commented. I think the previous owner hooked it up backwards. as in reversed the vacuum and gas, I have gas on the TOP and Vacuum on the bottom. Guess that explains a lot. Thanks guys. I'll pull it apart and move them where they are supposed to be.
 

steve.bright

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#16
Could be that the fuel side of the pump went bad and they tried moving the lines. Anyway, after running fuel in the vacuum pump, you might consider a rebuild kit from Walck or a new pump. Don't get rid of the original carb, people are looking for them in the for sale/wanted section pretty regularly.
 
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#18
Could be that the fuel side of the pump went bad and they tried moving the lines. Anyway, after running fuel in the vacuum pump, you might consider a rebuild kit from Walck or a new pump. Don't get rid of the original carb, people are looking for them in the for sale/wanted section pretty regularly.
No intention to dump it. I know how hard they are to find. I have two spare pumps, One is AC....the other I need to check, but that one looks beat to death.
 
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#19
I don't think there's any guarantee that the vacuum is on top and fuel on the bottom. I remember when I was growing up, one of my books (either the owner's manual or the service manual) had a picture of the pump being one way, and ours was the other way. But I do think, the fuel side has threaded fittings and the vacuum side has tubes you just slip the hose over.
 

Vintage Don

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#20
My money is on dirt in the system, holding the needle valve from closing. Stuff was apart, dirt got in somewhere. All it takes is a microscopic bit. Been there. When everything's eventually truly clean, it will be OK.
 
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