Carb leakes A LOT of gas - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**guyryan100** · 10-04-2002, 02:24 PM

Still trying to get the truck drivable. Upon startup, truck runs great for about 30 seconds. Then engine chokes and dies. At the same time, fuel begins to pour out of the rear of the carb. plenty of fuel pouring down onto the manifold. I don't get too close to the action at that point in order to get details, cause I don't want to be part of the charred remains. But if anyone knows how to resolve the problem ... Oh, I have a 6cyl engine and the simple Rodchester carb.

Thanks in advance!!

71GMC_3/4T · 10-04-2002, 03:06 PM

Pull the carb, take the top off it and put a new needle and seat in it. Check the float - maybe it's full of fuel. Check to be sure you have a fuel filter installed.

**COBALT** · 10-04-2002, 04:34 PM

Are you just finishing a rebuild? I had a similar problem with my Rochester 2bbl when I finally got it on the manifold. The fuel inlet has to have 2 washers: the metal one and a gasket BOTH, otherwise it will leak like crazy. Also the airhorn plate (the top part of the carb itself) needs to have the gasket inbetween it and the float bowl, AND it has to be perfectly aligned, and the screws that hold the main air horn plate down have to be tight, but don't strip them (aluminum wants to do that for some reason). You can get extra thick airhorn gaskets at NAPA. Maybe the one you have is too small.

Also the thing about the float: yes, you need to have that adjusted to the right level, otherwise it will never let the needle seat, and you'll have the bowl filling with fuel faster than the jets can throw it over the venturi (in which case you only have one). I'd check to make sure the bottom of the float at its low point and the mid seam of the float at its highest point is in the right range. Move the float in its entire range of motion, and make sure at its highest point it seats the needle. You'll probably have to check the kit you bought for the right distances from the float bottom-to-airhorn plate and float seam-to-airhorn plate, and measure them. If you can't get those measurements you'll have to keep adjusting the float until its at the right level.

Mine was spec'd to a 327, but I have a 350, so I had to cheat a little and guess. I split the difference between 350 and 327 and must'a got it right!

Good luck.

10-04-2002, 02:24 PM	#1
guyryan100 Registered User Join Date: Sep 2001 Location: Cumming, GA Posts: 470	Carb leakes A LOT of gas Still trying to get the truck drivable. Upon startup, truck runs great for about 30 seconds. Then engine chokes and dies. At the same time, fuel begins to pour out of the rear of the carb. plenty of fuel pouring down onto the manifold. I don't get too close to the action at that point in order to get details, cause I don't want to be part of the charred remains. But if anyone knows how to resolve the problem ... Oh, I have a 6cyl engine and the simple Rodchester carb. Thanks in advance!!

10-04-2002, 03:06 PM	#2
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Pull the carb, take the top off it and put a new needle and seat in it. Check the float - maybe it's full of fuel. Check to be sure you have a fuel filter installed. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO

10-04-2002, 04:34 PM	#3
COBALT Senior Member Join Date: Sep 2001 Location: Seattle, WA, USA Posts: 5,817	Are you just finishing a rebuild? I had a similar problem with my Rochester 2bbl when I finally got it on the manifold. The fuel inlet has to have 2 washers: the metal one and a gasket BOTH, otherwise it will leak like crazy. Also the airhorn plate (the top part of the carb itself) needs to have the gasket inbetween it and the float bowl, AND it has to be perfectly aligned, and the screws that hold the main air horn plate down have to be tight, but don't strip them (aluminum wants to do that for some reason). You can get extra thick airhorn gaskets at NAPA. Maybe the one you have is too small. Also the thing about the float: yes, you need to have that adjusted to the right level, otherwise it will never let the needle seat, and you'll have the bowl filling with fuel faster than the jets can throw it over the venturi (in which case you only have one). I'd check to make sure the bottom of the float at its low point and the mid seam of the float at its highest point is in the right range. Move the float in its entire range of motion, and make sure at its highest point it seats the needle. You'll probably have to check the kit you bought for the right distances from the float bottom-to-airhorn plate and float seam-to-airhorn plate, and measure them. If you can't get those measurements you'll have to keep adjusting the float until its at the right level. Mine was spec'd to a 327, but I have a 350, so I had to cheat a little and guess. I split the difference between 350 and 327 and must'a got it right! Good luck. __________________ '69 3/4 ton C20 2wd-350ci/TH400 '69 3/4 ton Custom 20 2wd-350ci/4sp Manual '99 2wd 5.7 Chevy Tahoe Seattle, WA.



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.