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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> Gas Engines >> Sticking carburetor
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Sticking carburetor - 1/2/2007 3:12 AM   
shoeless joe


 

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From: Carrollton, TX, USA
Status: offline 		I have a converted engine with a Walbro WT434 carburetor. Recently I began to have problems priming the engine and getting it started, if it has set for 2-3 days. It does not draw fuel from the tank. I can remove the plate and diaphragm and blow into and jiggle the inlet needle valve; put it back together and it woks fine until the next time it sits for a few days, after which I have to free the sticking needle again. I installed a carburetor kit (which included a new needle valve) and I soaked and blew out all parts of the carb using Barryman B-12. It was only a short time before the problem began recurring.

Has anyone else had this kind of problem? Or does anyone have a suggested fix.

Thanks


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RE: Sticking carburetor - 2/26/2007 3:32 AM   
captinjohn


 

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Status: offline 		I find it quite strange that no-one took the time to help you out. With only 1 post you must be new to this forum. I appoligize for the people that could have helped you but did not. I am not a pro on carbs but if you do not have it working by now...post a reply. Best Regards Capt,n

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RE: Sticking carburetor - 2/26/2007 2:25 PM   
Geistware



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Status: offline 		Make sure that your butterflys are not lose and are oriented so the barrel can close all the way.
This goes for the choke and the throttle.

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RE: Sticking carburetor - 2/26/2007 3:32 PM   
shoeless joe


 

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From: Carrollton, TX, USA
Status: offline 		Thanks for your responses. I had given up and hadn't been looking anymore until I got an e-mail from captainjohn.

This is a converted engine and the choke has been removed. I use an earplug glued to a 1" stick for a choke. So I'm sure I'm getting a good seal. This approach works great when the carb is drawing properly. It doesn't seem to me that during this choking step the throttle butterfly is in play.

What seems to be sticking is the inlet needle which is part of the metering system. With the installation of a new kit I replaced the inlet needle but it made no difference.

I have a farm, a lake place and a home. I run a lot of weed whackers with Walbro carbs that don't do this even when they have set over the winter.

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RE: Sticking carburetor - 2/26/2007 11:15 PM   
captinjohn


 

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Status: offline 		shoeless joe: Give this a try. Get a primer bulb that fits inline from tank to engine and install it. You will need a return line from carb back to tank. Use primer (really a purging devise) to get air out of lines then choke it to start. Keep us up to date on your progress. Best Regards Capt,n

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RE: Sticking carburetor - 2/27/2007 7:06 AM   
shoeless joe


 

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From: Carrollton, TX, USA
Status: offline 		Capt'n,
The primer bulb sounds like a great idea. My carb apparently had a bulb on it at one time. The additional brass tube (secondary port) has been capped off. I tried pumping from the tank into the primary inlet on the carb but I didn’t get any flow, and the fuel line remained filled with air. I hooked up a gauge on that input and it takes something in excess of 25 psi. to open the inlet needle.

I have re-plumbed a couple of weed whackers that had bulbs but simply hooked them back up the way they were without paying any attention to how the lines were run.

The primer bulb is marked carb and tank with the carb side being the suction side. So I tried to use the extra inlet that had been capped off. When I hooked up the suction side of the bulb to the secondary port (which is the way I believe it is supposed to be connected) I couldn’t seem to move any fuel.

If I can’t find the right hook up on the internet I plan to take one of my weed whackers apart to see how they are plumbed.

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RE: Sticking carburetor - 3/1/2007 3:30 PM   
shoeless joe


 

Posts: 4
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Joined: 3/2/2005
Last Login: 2/18/2008
From: Carrollton, TX, USA
Status: offline 		Capt'n,
I finally solved my problem. When I tried the primer bulb and couldn’t get it to pull gas I realized my problem was more serious than I thought. The more I worked on it the worse things got until I finally reached a point where I could no longer get my engine to run beyond the prime I squirted in the carb. I finally found a good Web Site (http://wind-drifter.com/technical/wg8walbro.htm) that describes a WG series carburetor. Although it was not the same as mine it gave me the clue I was looking for. I made a tool similar to the Walbro Part # 500-13-1, and bent the metering lever to the correct height.

When I did this I was amazed at how easy it was to bend and realized my aggressive use of an air gun was my enemy.

I don’t believe I will need the primer bulb now, but, only time will tell. At least I have that option as a fall back and will carry one in my flight box for a temporary hook up as needed.

Thanks, for you positive outlook. It kept me going.

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