Zeinth #29 help

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chris
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Zeinth #29 help

Post by chris » Tue Oct 31, 2017 11:20 am

Had it rebuilt about a year ago, i finally have time to get it on and i think it has a vacuum leak, Once it starts up runs for about 20 seconds but when i give it throttle , it will throttle UP and dies right back to and idle , it go no higher than like 800 too 1000 RPMs. I didn't touch the Governor at all neither did the rebuilt place.


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Tankdriver
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Re: Zeinth #29 help

Post by Tankdriver » Tue Oct 31, 2017 4:51 pm

Sounds like you main jet may be partially stopped up. It does not have a acc pump, like most cars, that is linkage operated. It works off vacuum. When the vacuum get low, it drops a plunger, that functions as the acc pump.

It also has a separate idle circuit(jet). So it is idling ok, up goose the acc, the acc plunger drops squirting the gas in to the carb, when that gas runs is used up, it drops back to the idle circuit.

Check your main jet. Or trash in the bowl, getting sucked up.....

Maybe.... :D
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Re: Zeinth #29 help

Post by chris » Mon Dec 25, 2017 2:40 pm

You know a good carb guy ?

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Re: Zeinth #29 help

Post by johnseidts » Tue Dec 26, 2017 3:10 pm

If the carb checks out, check the fuel pump. I missed a step in rebuild, and this is exactly the result I had. The step I missed- when assembling the diaphragm chamber, you must fully deflect the cam kicker arm as you are tightening the chamber back together to compress the diaphragm. If you don't do this step, the diaphragm doesn't have enough travel to supply enough fuel to the carb at higher throttle settings. You get good idle, but inability to accelerate.
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Re: Zeinth #29 help

Post by chris » Wed Dec 27, 2017 2:28 pm

I put in a new repro ( airtex ) fuel pump when the carburetor was put back on

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Re: Zeinth #29 help

Post by dpcd67 » Fri Dec 29, 2017 9:47 am

I hate vacuum operated accelerator pumps, like yours, and the later Carter ones too. They were made to go under water. I like to see a mechanical arm make the pump operate, but for these, we are stuck.
I send my Carter carbs to Vintage Power Wagons and they do a great job. But I do not know if they rebuild the Zeniths.
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Re: Zeinth #29 help

Post by W. Winget » Sun Jan 21, 2018 2:18 pm

When mine did this, it turned out to be the fuel line leading to the Fuel pump (braided covering) down by the front of the engine. The rubber was cracked and allowed air to suck in when speed increased, but would only allow idle speed once the carb fuel ran out. Changed that and it was solved.
Another time my pin had creeped out of the fuel pump lever making it act like vapor lock.
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