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-   -   Walbro problem....need ideas! (https://www.rcuniverse.com/forum/gas-engines-142/9836145-walbro-problem-need-ideas.html)

BOB275 06-30-2010 09:02 AM

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

Tired Old Man 06-30-2010 10:26 AM

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?

w8ye 06-30-2010 12:05 PM

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

BOB275 06-30-2010 12:51 PM

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................

BOB275 06-30-2010 12:58 PM

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

w8ye 06-30-2010 01:06 PM

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...&Series=WT



BOB275 06-30-2010 01:37 PM

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.

AA5BY 06-30-2010 03:08 PM

RE: Walbro problem....need ideas!
 
No spring on metering valve... I reckon it would flood... big time.


Eganwp 06-30-2010 04:07 PM

RE: Walbro problem....need ideas!
 


ORIGINAL: AA5BY

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


Yep!

Ram-bro 06-30-2010 05:16 PM

RE: Walbro problem....need ideas!
 
where do you get the rebuild kits?

BOB275 06-30-2010 05:21 PM

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.

Ram-bro 06-30-2010 05:27 PM

RE: Walbro problem....need ideas!
 
thanks Bob

w8ye 06-30-2010 06:45 PM

RE: Walbro problem....need ideas!
 
You can get the diaphragm/ rebuild kits at most any chain saw store

racelikustolit3k 07-01-2010 09:24 AM

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

BOB275 07-01-2010 09:30 AM

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

budchugger 07-01-2010 11:03 AM

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.

racelikustolit3k 07-01-2010 11:53 AM

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)

BOB275 07-01-2010 12:02 PM

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.

BOB275 07-01-2010 12:07 PM

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.

w8ye 07-01-2010 12:32 PM

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


AA5BY 07-01-2010 12:47 PM

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.

BOB275 07-01-2010 01:16 PM

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.

AA5BY 07-01-2010 01:38 PM

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.

racelikustolit3k 07-01-2010 01:47 PM

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


w8ye 07-01-2010 02:16 PM

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

racelikustolit3k 07-01-2010 02:20 PM

RE: Walbro problem....need ideas!
 
already tired that.. yes it is seated

I have tried it both ways by bending the tab

it does the same exact thing both ways

w8ye 07-01-2010 02:39 PM

RE: Walbro problem....need ideas!
 
The fuel from the pump has to come up that passage way where the needle and seat is to ever get into the throat of the carb and into the engine.

Tx_RcFlyer 07-01-2010 03:18 PM

RE: Walbro problem....need ideas!
 


ORIGINAL: racelikustolit3k

already tired that.. yes it is seated


It's seated against a bunch of varnish and gunk. Take it apart and either soak it in some carb cleaner or use the spray cleaner and spray down where that needle seats to get all that varnish and crap out of there. I just went thru this with my G38 and had the exact same symptoms you described.



racelikustolit3k 07-01-2010 03:27 PM

RE: Walbro problem....need ideas!
 
ITS A BRAND NEW CARB

there is no junk in it and im not an dunce!!!!

there is a crack in the case on the new carb, straight from horizion.. so back it goes again

the crack goes from the small hole where the fuel enters the fuel pump (just on the other side of the fuel line barb) side straight the throat

problem solved

spaceworm 07-01-2010 03:49 PM

RE: Walbro problem....need ideas!
 


ORIGINAL: AA5BY

"... Also it has been documented that an acetate (bluish) pump will not pump adequately to provide fuel overhead for the engine to cool properly..."

Please, where is the documentation citing that the blue acetate diaphram does not pump enough? And, what is "fuel overhead" and it's impact on proper cooling.? I have never heard this before. I am running one on my G23, my Craftsman blower and my Weedewater trimmer.

This is a serious request from me. Please cite your information sources.

Thank you very much.

Sincerely,

Richrad

The Ghost 07-01-2010 05:17 PM

RE: Walbro problem....need ideas!
 
[link=http://wem.walbro.com/distributors/servicemanuals/]HERE[/link] is the link to setup and adj for all Walbro carby models.

Cheers

AA5BY 07-01-2010 05:49 PM

RE: Walbro problem....need ideas!
 
The documentation that I speak of is a chart that has been posted on this forum a couple of times that shows the characteristics of the various Walbro pumps and it list the acetate pump as the weakest. I don't have a link to that chart but a search should find it without much difficulty.

One of the threads that I posted with my problem is at

http://www.rcuniverse.com/forum/m_9746155/tm.htm

There was another thread where the discussion of fuel overhead took place.

I'm cramped for time right now but will reference it to you later if I can find it.

You will find that current G-20s and G-26s are fitted with the teflon pump.

Antique 07-01-2010 06:52 PM

RE: Walbro problem....need ideas!
 
Any of the diaphragms will work just fine..

BOB275 07-01-2010 06:52 PM

RE: Walbro problem....need ideas!
 
OH THIS IS GOING TO BE REMEMBER FOR A LONG TIME TO COME!
I took the good carb off the other 26cc I have (identical except for the wt #. Mounted it on the ZENOAH
and it would not start. Damn not again! This has got to be something with the spark. Got another CDI
that was on the 26cc and put that on the zenoah and the 26cc carb STARTED RIGHT UP. Took the
26cc carb off and installed the original WT811, BANG IT STARTED RIGHT UP and tuned it up. Runs great!
OH HAPPY DAYS ARE HERE AGAIN!
Learned a lesson on not to trust what you got laying around unless it's brand new.

Gentlemen thank you for so many wonderful hints. Bob

Tired Old Man 07-01-2010 07:27 PM

RE: Walbro problem....need ideas!
 
Pleased to hear the matter is resolved.

spaceworm 07-01-2010 07:42 PM

RE: Walbro problem....need ideas!
 
Many times many years ago, I rebuilt many automobile carbs (remember those), and when that did not solve the problem changed plugs, and or plug wires, and or points and condensors (remember those), and THAT was the problem almost every time. Then hopefully I had not screwed up the carbs so they would not work right ever again.

But then early fuel injection was not always without blame (remember VW and the "Porsche" 912?), nor were early capacitive discharge ignition systems (homebuilt).

Sincerely,
Richard

w8ye 07-01-2010 08:06 PM

RE: Walbro problem....need ideas!
 
Before computers, engines were more simple. You could tell by ear what the problem was.

They are simple now if you have a device to read the computer. The OBDII requires a reader where with the early computers you could pull up the codes with the ignition switch.


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