Carb problems please read below

bobeeker

Cadet
Joined
May 3, 2009
Messages
19
Ok I had a carb that was not allowing my boat to take off and plane out. I sent the carb to Flyfishcarbs and they rebuilt it. I installed the carb back on and took the boat to the intercoastal waterway. It ran great for about an hour. It took off like it was supposed to and ran the best the boat has ever ran since i owned it. Then all the sudden it started spitting and spudering and before i could get the boat cut off we pulled the motor cover off and there was fuel bubbling out of the carb at the top and the overflow barb fitting. I was told by the rebuilder must have picked up a piece of trash and tried the few things they recommended like running carb out of gas and filling it back up a few times and pecking on the bowl. Well non of this worked so I took the card off and took the bowl off. I cleaned it al back out removing the needle and float. Put it all back together and put it back on and its still pushing fuel out of the little 90deg tube that dumps back into the carb in a straight flowing stream. What am i Missing or how do i fix this problem now???? I have 5psi coming out of the exterior fuel pump. Is it somehow when all hooked up building more pressure when running? The fuel pump is hooked up to the oil pressure switch so it only runs when engine is running.......... Please help!!! I only get 2 weeks vacation a year and this one is being spent working on my boat yet again. Thanks so much in advance. Joe
 

stonyloam

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Mar 13, 2009
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5,827
Re: Carb problems please read below

s still pushing fuel out of the little 90deg tube that dumps back into the carb in a straight flowing stream.

Isn't that fitting attached to the clear line from the pump? Is the clear line filled with fuel? If it is you have a ruptured diaphragm in the pump and it is dumping gas into the carb. Just a guess from your description need to know what engine and carb.
 

bobeeker

Cadet
Joined
May 3, 2009
Messages
19
Re: Carb problems please read below

5.0L engine with Holly 2 barrel carb but there is no clear line. The only line on this carb is the black hose that brings the fuel in to the carb from the fuel pump.

Isn't that fitting attached to the clear line from the pump? Is the clear line filled with fuel? If it is you have a ruptured diaphragm in the pump and it is dumping gas into the carb. Just a guess from your description need to know what engine and carb.
 

ktbarrentine

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Dec 12, 2011
Messages
1,296
Re: Carb problems please read below

From the sounds of the post, electric fuel pump.... I was thinking the same thing as Terry until I reread the original post.
 

stonyloam

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Mar 13, 2009
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Re: Carb problems please read below

Dang I thought I had it there. Sounds like for some reason the needle is not closing off the flow, but you already know that. Good luck!
 

Boland01

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Joined
Aug 10, 2012
Messages
15
Re: Carb problems please read below

Did you verify your carb float level was in spec and in good shape (not too heavy from fuel absorbtion)? On my Mercarb there are two measurements you need to take. One with the float hanging down and one with it upside down.
 

fasteddy3243

Recruit
Joined
Sep 5, 2012
Messages
3
Re: Carb problems please read below

The needle valve is not sealing. To verify, remove carb top and blow into fuel inlet while pressing float up. If that seals, check float for sloshing/leaking/misadjustment (it is very easy to mess up float adjustment in shipping). It is possible that the electric fuel pump is pushing too much pressure, in which case you need a fuel pressure regulator. Holley makes a good one.
 

Oshkosh1

Ensign
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Jun 8, 2009
Messages
968
Re: Carb problems please read below

Did you verify your carb float level was in spec and in good shape (not too heavy from fuel absorbtion)? On my Mercarb there are two measurements you need to take. One with the float hanging down and one with it upside down.

If you still have a nytrol float...replace it with a brass one as long as you have it apart. New ethanol blends don't play well with the seams of the nytrol floats...brass is virtually impervious.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: Carb problems please read below

Need some engine information. Per your other post http://forums.iboats.com/showthread.php?t=574832 you have an OMC engine, yet you say you have an oil pressure switch for the fuel pump. What year is your engine? OMC doesn't use an oil pressure switch, unless it's an aftermarket setup. Which then leads to what fuel pump you have.

Big question is how much fuel pump pressure do you have? EDIT disregard, re-read and see you have 5 psi pressure.
 
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