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Walbro problem....need ideas!

Old 06-30-2010, 09:02 AM
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BOB275
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Default Walbro problem....need ideas!

After several months sitting I took the aircraft out to fly with the ZENOAH 20cc with a WALBRO WT811 carb. 2 dead sticks later I decided to tune it up. I couldn't get it started, replace batteries, spark plugs, CDI, and gasoline. Got the spark ok, but no start. Went out and got a carb parts kit and replace several gaskets and diaphram. Still couldn't get it started.
I did notice the more I tried the more the fuel was dripping and several times the engine was flooded. HELP! Bob
Old 06-30-2010, 10:26 AM
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Tired Old Man
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Default RE: Walbro problem....need ideas!

Check the metering needle is not stuck open inside the carb. After the rebuild, did you orient the gaskets and carb base correctly over the pulse port?
Old 06-30-2010, 12:05 PM
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Default RE: Walbro problem....need ideas!

On the regulator side, the gasket goes on first and the the diaphragm goes on and the cover and four screws

http://wem.walbro.com/distributors/s...s/WTseries.pdf
Old 06-30-2010, 12:51 PM
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BOB275
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Default RE: Walbro problem....need ideas!

OH, OH, I didn't see the FUEL PUMP SPRING! Got to clean the work bench now out in the HOT garage. Standby................
Old 06-30-2010, 12:58 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: w8ye

On the regulator side, the gasket goes on first and the the diaphragm goes on and the cover and four screws

http://wem.walbro.com/distributors/s...s/WTseries.pdf
See my post, no spring
Old 06-30-2010, 01:06 PM
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Default RE: Walbro problem....need ideas!

The Walbro WT811 doesn't have a spring on the fuel pump side.

There is supposed to be a spring on the regulator side that holds the needle and seat closed

http://wem.walbro.com/walbro/product...11-1&Series=WT


Old 06-30-2010, 01:37 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: w8ye

The Walbro WT811 doesn't have a spring on the fuel pump side.

There is supposed to be a spring on the regulator side that holds the needle and seat closed

http://wem.walbro.com/walbro/product...11-1&Series=WT


That's correct on no spring as I looked at 2 other Walbro carbs, different models. Yes the spring to hold the needle is there.
Back to the drawing board or take another good walbro on a 26cc and try it.
Old 06-30-2010, 03:08 PM
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Default RE: Walbro problem....need ideas!

No spring on metering valve... I reckon it would flood... big time.

Old 06-30-2010, 04:07 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: AA5BY

No spring on metering valve... I reckon it would flood... big time.

Yep!
Old 06-30-2010, 05:16 PM
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Default RE: Walbro problem....need ideas!

where do you get the rebuild kits?
Old 06-30-2010, 05:21 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: Ram-bro

where do you get the rebuild kits?
Local hobby shop. ZENOAH #2372, Horizon Hobby has them. About 7-8 dollars.
Old 06-30-2010, 05:27 PM
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Default RE: Walbro problem....need ideas!

thanks Bob
Old 06-30-2010, 06:45 PM
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Default RE: Walbro problem....need ideas!

You can get the diaphragm/ rebuild kits at most any chain saw store
Old 07-01-2010, 09:24 AM
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Default RE: Walbro problem....need ideas!

I am going though the same problems with a g20ei, seems this a common problem..

does anyone have a spare 811 they would like to sell




thanks jessie
Old 07-01-2010, 09:30 AM
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Default RE: Walbro problem....need ideas!


ORIGINAL: racelikustolit3k

I am going though the same problems with a g20ei, seems this a common problem..

does anyone have a spare 811 they would like to sell




thanks jessie
I'm going to try later today. I cleaned and blew out the canals. If that doesn't work I'll take another Walbro from my 26cc engoine and try it. Hope it's not to hot later today. Have you tried a carb repair kit?? Bob
Old 07-01-2010, 11:03 AM
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Default RE: Walbro problem....need ideas!

When you had it apart did you clean the screen? Sounds like it might be dirty as it don't take much to clog it up.
Old 07-01-2010, 11:53 AM
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Default RE: Walbro problem....need ideas!

yep I put a new carb kit in it. but now when I roll the engine over it will completely fil the jug with fuel.. even closing the H/L speed needles it is still pumpin fuel through the carb (this one has me scratching my head)
Old 07-01-2010, 12:02 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: budchugger

When you had it apart did you clean the screen? Sounds like it might be dirty as it don't take much to clog it up.
That was the first thing I thought of. Clean as a whistle. I have recently clean and blew the holes out.
Old 07-01-2010, 12:07 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: racelikustolit3k

yep I put a new carb kit in it. but now when I roll the engine over it will completely fil the jug with fuel.. even closing the H/L speed needles it is still pumpin fuel through the carb (this one has me scratching my head)
My hair is falling out from scratching so much. If you come up with a fix, please let me know.
Old 07-01-2010, 12:32 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: BOB275


ORIGINAL: racelikustolit3k

yep I put a new carb kit in it. but now when I roll the engine over it will completely fil the jug with fuel.. even closing the H/L speed needles it is still pumpin fuel through the carb (this one has me scratching my head)
My hair is falling out from scratching so much. If you come up with a fix, please let me know.
The needle is not seating in the regulator

pop off pressure = Zero

Old 07-01-2010, 12:47 PM
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Default RE: Walbro problem....need ideas!

Bob, I thought you had found the problem to be the small spring left out from under the metering needle? If it is still flooding, do you ever get a pop before the cylinder gets flooded to much? Maybe no spark?

Also, the metering diaphragm must not be hard or misshaped. It must be turned so that the anvil hits the rocker arm of the metering valve.

If it runs but closing the mixture needle fully does not lean out the engine then the metering diaphragm has likely gotten too hard to function properly or there is dirt in the needle seat.

If it will not richen adequately, the pump is not functioning properly due to wore out pump diaphragm or pump valves. Also it has been documented that an acetate (bluish) pump will not pump adequately to provide fuel overhead for the engine to cool properly.
Old 07-01-2010, 01:16 PM
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Default RE: Walbro problem....need ideas!


ORIGINAL: AA5BY

Bob, I thought you had found the problem to be the small spring left out from under the metering needle? If it is still flooding, do you ever get a pop before the cylinder gets flooded to much? Maybe no spark?

Also, the metering diaphragm must not be hard or misshaped. It must be turned so that the anvil hits the rocker arm of the metering valve.

If it runs but closing the mixture needle fully does not lean out the engine then the metering diaphragm has likely gotten too hard to function properly or there is dirt in the needle seat.

If it will not richen adequately, the pump is not functioning properly due to wore out pump diaphragm or pump valves. Also it has been documented that an acetate (bluish) pump will not pump adequately to provide fuel overhead for the engine to cool properly.
The spring wasn't needed for the 811 carb.It was a bigger spring on the other side. I already replaced the gasket and diaphragm from the kit. The only part that isn't the right one was the needle. My kit was for a G23 carb. Same gaskets but different needle.
Funny it will fire on the first try and quits and won't start again.
In about 2-3 hours I will try again. And maybe try another Walbro carb from a 26cc engine.
Old 07-01-2010, 01:38 PM
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Default RE: Walbro problem....need ideas!

Ahhh, if it fires the first time and then no more... it tells that ignition is ok but carb is flooding. I'd close the high speed to about two turns out, and make sure the throttle is cracked open enough for starting and that the choke is opened after the pop. If that fails, then recheck everything on the metering system under the plate that has the four small screws. It has the symptoms of the metering needle not closing. Causes for that are 1. the little spring is missing or misaligned under the rocker arm. 2. dirt in the needle seat. 3. wrong metering needle. 4. diaphragm bulged inward and not allowing needle to close. 5. atmosphere hole clogged and not allowing fuel pressure to move the diaphragm outward.
Old 07-01-2010, 01:47 PM
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Default RE: Walbro problem....need ideas!

I am workin on mine right now, and its still kickin my A%$..

when I put the fuel line on, I can roll the engine over about 10 times (choke open) until the engine hydrolocks(jug completely full of fuel).. I dont get it at all everything was replaced just exactly like factory..

any thoughts on this??

I am about th just buy a new carb from HH and see if it fixes the problem

Old 07-01-2010, 02:16 PM
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Default RE: Walbro problem....need ideas!

It is still the fact that the needle is not seated due to the reasons listed a couple posts above

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