johnny bubba

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Hey all I have a very old Zenoah 35, think this is the model that was before the 38. Any way I have had this engine for manyt many happy years of flying. After a year off from RC, getting everything ship shape again for flying.

got a problem. Redid all the fuel lines and made sure they were right and tight. Reinstalled tank. Tried to fire up engine. No go. Does not seem that the gas is getting sucked into carb. When I prime the carb, the engine starts on the first release of the spring starter. Runs until fuel in carb is gone. Took off carb and looked at gasket btw carb and engine. HELL IF I KNOW WHAT TO LOOK FOR! Is there a way to tell if the gasket is bad and needs replacing?

What would you do to pin down exactly is wrong with this motor? Appreciate any help offered.

karolh

Sounds like it's only running long enough to burn off the prime, which could mean that the carb is not pumping or there is some debris blocking the carb's internal filter screen. It might be time for a well needed carb clean including a repair kit and new diaphram.

Karol

johnny bubba

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Thanks. Now looking for parts and all, I am beginning to wonder. Did zenoah ever make a 35cc or could this be a Quadra? I know Quadra used to make a 35cc, but I cant find any info on a zenoah 35cc. MMmmmm CRUD!!!

A carb rebuild kit should not really matter much I think. How can I tell if the carb insulator gaskets are ok? Could this be the problem. Just trying the easy route before having to rebuild a carb, which I have never done.

johnny bubba

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Now my brain is about to explode!! Do I get a rebuild kit for a captive or non-captive. Feeling mighty dumb....

johnny bubba

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how can I ID the maker of this engine. Seems that zenoah only make a 35cc marine engine.

R Plante

There should be a number on the carb engine make won't matter. If you are not comfortable a local small engine shop will rebuild and basic set the needles for you. You will still have to fine tune but it will get the engine running. Not an expensive item

johnny bubba

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thanks again.

arobatx

The diaphragm is likely stiff and unable to pump the fuel...and though that may be the only thing holding you up, with the carb partially apart, it would make good sense to visually inspect and clean the filter screen, and give it a good cleaning inside and out. If you plan to have your local mower shop do this for you, make note of where your carb needles are currently set before handing it over, so you have a ballpark idea of where things might end up when you re-tune. don't expect that they will be in the same position after a good cleaning and a replacement part or two when you retune it, but it would be good to have an 'idea'.

Chad

johnny bubba

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Thanks. I did note that when I took the carb off the engine to take a look see, it was not attached very tightly. Could the gasket from the carb to the engine been leaking and this causing the no fuel draw situation?

arobatx

Yes, there is a pulse port in the cyl case, carb block and gaskets, that allows case pressure to 'pulse' through to the carb and diaphragm to meter the fuel. If the pulse goes anywhere but through the port properly, and without leaking, it could weaken or not even be present, preventing the correct metering, or pumping of fuel once running. This could explain why after choking it will run briefly, but nothing beyond that.

Chad

arobatx

Seriously though....once you are monkeying with it at all, it would be well worth your time to tidy things up, and at the least, replace the diaphragm. Then you can look forward to some significant run time before further attention is required.

Chad

johnny bubba

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Thanks Again. Can I send the carb to you with a check for rebuilding if this is not the problem?

arobatx

Haha....I understand how intimidating a carb rebuild might sound, when you haven't done it. But you have to trust us here, and know that it is not a big deal, and certainly not worth shipping it off somewhere to have it done. your local outdoor power equipment shop can easily get you the parts, either with the carb in hand, or the number off of it, and they can even rebuild it for you without extensive cost or time involved at all. No worries man!


Chad

johnny bubba

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So that is a no eh? LOL, appreciate all the advice. Any idea where I can find pics of a break down and rebuild of a walbro carb??

arobatx

http://wem.walbro.com/distributors/servicemanuals/

or type in the walbro part number in the upper right on this page:

http://wem.walbro.com/walbro/family.asp

(I'm guessing that it is a walbro) You will find the number stamped right onto the carb...

Chad

johnny bubba

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THANKS!!!!!

arobatx

www.bennettbuilt.com is also a good source for Quadra and Zenoah parts and service items I would be surprised if Dick doesn't have carb kits as well.

Chad

johnny bubba

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OMG!! All those tiny parts!!!