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Old 03-18-2020, 08:21 PM   #1
Dougs 28
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Default Zenith-ll carburetor question

I have a Zenith-ll carburetor on the 28 and I have a problem with it leaking through the intake. The A runes great when I take it out for a drive and then when I come back and park it, the carb doesnít leek for hours, then Iíll check it the next morning and it has leaked. Every time I get done driving it I shut the gas off from the the tank. So Iím not sure if the float is sticking or if it could be something else...?

Doug
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Old 03-18-2020, 08:43 PM   #2
DBrer
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Default Re: Zenith-ll carburetor question

Probably the float valve. If it leaks slowly it takes somtime to overflow the float bowl, I had this problem just last week.
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Old 03-18-2020, 08:48 PM   #3
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Default Re: Zenith-ll carburetor question

Dougs 28, Read the article by Tom Endy on Zenith carburetor restoration tips, that helped me tremendously. Mine is working great now.
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Old 03-18-2020, 09:18 PM   #4
Ernie Vitucci
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Default Re: Zenith-ll carburetor question

Good Evening...Sometimes this leak is a combination of a leak in the shut off valve under the dash combined with the float valve and the head pressure coming from the dribble of the under dash valve. A quarter turn shut off valve from Bratton's that will not leak can sometimes/often cure the problem of the two old fashioned valves dribbling tiny amounts of fuel...Ernie in Arizona
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Old 03-18-2020, 09:21 PM   #5
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Default Re: Zenith-ll carburetor question

If the jets are not installed at the right height (ie, too low), fuel will run through them if the float valve and tap leak.
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Old 03-18-2020, 09:27 PM   #6
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Default Re: Zenith-ll carburetor question

To isolate the carb from the under tank shutoff, disconnect the gas line into the carb.
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Old 03-18-2020, 09:40 PM   #7
Dougs 28
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Default Re: Zenith-ll carburetor question

Thanks for the info, guys, Iíll check out Tom Endyís article on Zenith Carburetors and go from there. Appreciate the advise..

Doug
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Old 03-18-2020, 09:58 PM   #8
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Default Re: Zenith-ll carburetor question

Quote:
Originally Posted by Ernie Vitucci View Post
Good Evening...Sometimes this leak is a combination of a leak in the shut off valve under the dash combined with the float valve and the head pressure coming from the dribble of the under dash valve. A quarter turn shut off valve from Bratton's that will not leak can sometimes/often cure the problem of the two old fashioned valves dribbling tiny amounts of fuel...Ernie in Arizona
Leaky shut off valve is a real possibility. Recommend disconnecting the fuel line at the carb and placing it in a bottle overnight in a bottle with the shut off closed. Mine would leak about two oz. overnight and resulted in a carb leak which left gas fumes in the entire garage. New shut off valve fixed the problem.
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Old 03-18-2020, 10:13 PM   #9
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Default Re: Zenith-ll carburetor question

You should be able to leave the tank valve on all the time, even if it leaks. the float valve should keep gas from leaking so if you have a carburetor leak the float valve is bad. I would still change the tank valve if its bad. I do shut off the tank valve when the car is going to sit for awhile just in case the float valve fails.
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Old 03-18-2020, 10:28 PM   #10
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Default Re: Zenith-ll carburetor question

A while back I bought an electric shut-off valve so I didn't have to worry about it. I still shut off the manual tank valve when I park for long periods of time. However, even before that I never had any carb leakage when leaving the tank valve on. I guess I should call myself lucky.
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Old 03-18-2020, 10:52 PM   #11
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Default Re: Zenith-ll carburetor question

I have found that the float can contribute to the problem. You need to inspect carburetor float hinge bracket, frequently the float valve needle will wear a dimple in the hinge bracket and the dimple will impede the float travel and thus not completely seat the needle in the float valve. See the below photos of two floats with dimples from years of contact with the float valve needle.

I have sanded the bracket to remove the dimple.
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File Type: jpg P1020487 resize_LI (2).jpg (63.4 KB, 31 views)
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Old 03-19-2020, 07:26 PM   #12
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Default Re: Zenith-ll carburetor question

Quote:
Originally Posted by Ernie Vitucci View Post
Good Evening...Sometimes this leak is a combination of a leak in the shut off valve under the dash combined with the float valve and the head pressure coming from the dribble of the under dash valve. A quarter turn shut off valve from Bratton's that will not leak can sometimes/often cure the problem of the two old fashioned valves dribbling tiny amounts of fuel...Ernie in Arizona
Your right Ernie, that positive 1/4 turn shut off from Brattons has worked well for me. Been 5 years.....no leaks.
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Old 03-20-2020, 09:54 AM   #13
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Default Re: Zenith-ll carburetor question

I like to isolate 1st. Turn off the shutoff, take gas line off at carb, let gas line drain dry for a couple of hours, stick a small jar with a piece of paper/tissue in the jar under the free end of the gas line and let sit overnight. If gas in the jar, or paper is stained, fix the shutoff. Put the gas line back on the carb, test overnight with the shutoff off, check the carb air intake for gas Turn on shutoff on and leave overnight, if leaks fix carb.
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Old 03-20-2020, 08:02 PM   #14
doa44green
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Default Re: Zenith-ll carburetor question

My Zenith II has gas that wicks up the wall of the inside of the carb. and runs over at the gasket surface. No opne has been able to solve that problem for me yet.
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Old 03-21-2020, 04:42 AM   #15
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Default Re: Zenith-ll carburetor question

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Originally Posted by doa44green View Post
My Zenith II has gas that wicks up the wall of the inside of the carb. and runs over at the gasket surface. No opne has been able to solve that problem for me yet.
Why not make that a sepearte thread- you'd have lots of opinions I'm sure- Maybe be even some useful stuff
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Old 03-21-2020, 07:41 AM   #16
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Default Re: Zenith-ll carburetor question

double post ...
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Old 03-21-2020, 07:43 AM   #17
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Default Re: Zenith-ll carburetor question

,,,

Last edited by Benson; 04-11-2020 at 07:55 AM. Reason: clarification of text
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