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Old 07-20-2017, 09:03 PM   #41
barnstuf
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Default Re: Starving for gas at highway speed

A friend purchased one of the new Zenith carburetors that have been on the market for quite a few years, and up to 45 mph everything was fine, over 45 he experienced hesitation and starving for gas. He tried to find the problem without result and turned the carburetor over to a professional Zenith restorer. After serious testing he found the secondary well side opening was a tiny bit too small so he enlarged it to proper specs and the problem was solved.
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Old 04-14-2021, 04:50 PM   #42
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Default Re: Starving for gas at highway speed

Chris - I was reading through this 4-year-old thread of your problem with cutting out above 40mph or so. I was saddened to see the thread end with no solution as I am having same issue. I have rebuilt carb, new ignition, checked fuel, etc, etc. Did you ever resolve yours? Thx...
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Old 04-14-2021, 05:37 PM   #43
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Default Re: Starving for gas at highway speed

King, if you put a new fuel line on check that you don’t have more than 1/8 inch of tubing beyond the ferrule. Common problem. Good luck.
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Old 04-14-2021, 08:51 PM   #44
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Default Re: Starving for gas at highway speed

Sounds like a carburetor problem. Try a different one and if that works take the old carburetor apart to check for good flow through the float valve, the correct float level, correct jets with no clogs, jets tight in their threads, vacuum leaks at throttle arm or flange, etc.
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Old 04-14-2021, 08:53 PM   #45
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Default Re: Starving for gas at highway speed

By the way, the water will be yellow because of the rust it has picked up and the gasoline will look clear with the small volume. Keep emptying the water out of the sediment bowl.
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A is for apple, green as the sky.
Step on the gas, for tomorrow I die.
Forget the brakes, they really don't work.
The clutch always sticks, and starts with a jerk.
My car grows red hair, and flies through the air.
Driving's a blast, a blast from the past.
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Old 04-14-2021, 10:42 PM   #46
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Default Re: Starving for gas at highway speed

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several years ago, there were some poor quality carburetor float valves made with a very small hole for the fuel to pass thru. The car would run fine around town but get it on the highway and it would starve for fuel. When this would happen if you would let up on it for a little while it would get enough fuel to run for just a little more and then start starving again. I ran into this on a Model A of one of our club members. Took the carb apart and found a float valve with a very small hole in it. Replaced the valve, car then ran just fine.

If you have a good steady stream of fuel with the fuel line removed from the carburetor, you may want to check the float valve.

My experience, Chris W.
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Old 04-14-2021, 10:57 PM   #47
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Default Re: Starving for gas at highway speed

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Originally Posted by CWPASADENA View Post
several years ago, there were some poor quality carburetor float valves made with a very small hole for the fuel to pass thru. The car would run fine around town but get it on the highway and it would starve for fuel. When this would happen if you would let up on it for a little while it would get enough fuel to run for just a little more and then start starving again. I ran into this on a Model A of one of our club members. Took the carb apart and found a float valve with a very small hole in it. Replaced the valve, car then ran just fine.

If you have a good steady stream of fuel with the fuel line removed from the carburetor, you may want to check the float valve.

My experience, Chris W.
Do you know the office size on the float valve? I’ve seen the spec somewhere, but sure where.
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Old 04-15-2021, 10:14 AM   #48
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Default Re: Starving for gas at highway speed

Since he hasn't answered must be he got disgusted and sold the monster !

I still think he just had a gas cap issue.
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Old 04-15-2021, 10:42 PM   #49
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Default Re: Starving for gas at highway speed

Do you know the office size on the float valve? I’ve seen the spec somewhere, but sure where.

I am not at my shop where I could measure an original and off the top of my head, I do not know the size of the opening in the float valve but if you take it out and look at it, it is obvious that it is a very small hole.

I know Brattons has good valves and I am sure other of the parts suppliers also do. I would not recommend Mac's as most of their stuff comes from China.

Chris W.
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Old 04-15-2021, 11:48 PM   #50
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Default Re: Starving for gas at highway speed

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Since he hasn't answered must be he got disgusted and sold the monster !

I still think he just had a gas cap issue.

Probably not as he was online here today around 9:30 Pm.
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Old 04-16-2021, 07:49 AM   #51
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Default Re: Starving for gas at highway speed

Just fixed a similar problem with my 28. Ordered a pencil filter for the tank and when I drained the gas and pulled the tank valve, found that valve was only about 1/3 open when turned to open. Removed the valve core and drilled the passageways out larger, ground and amount of the lever stop arm and put a metal ship in the lever opening to tighten it up. Problem solved!
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Old 04-16-2021, 11:06 AM   #52
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Probably not as he was online here today around 9:30 Pm.





That was said ' tongue in cheek ' since he didn't bother to let us know what he found.
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