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"Dry Carb" Restarting

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Old 06-14-2009, 08:36 PM
  #76  
av8tor1977
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What I have done is go to using an "after run fuel", and leave it in the carb. I use a mixture of Coleman Camp fuel, Sta-Bil, and Pennzoil at 20 to 1 ratio. After flying, I drain my normal fuel out of the tank, and then put in about a half tank of my after run fuel. I run the engine at various throttle settings long enough to be sure the fuel is thoroughly through the carb/engine, then I shut down, drain the tank, and store the plane. I am doing this on five of my flying planes right now but I've only recently started; time will tell if it will help my diaphragms last longer, and keep the carbs "wet" and ready to go, but I think it will.

Other than that idea, one has to realize that Walbro has been aware of this problem, and has addressed it. On nearly every piece of equipment with a Walbro carb, you will find a primer bulb. I know we don't like to use a primer bulb on our planes, but an easy substitute could be used. Just run a capped line to a fuel dot from the carburetor primer port. Then use a large syringe to draw fuel through the carb just like the primer bulb used to do. That will fill the carb and solve the problem, just as it did for Walbro in their tool/equipment applications....

AV8TOR
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Old 06-14-2009, 08:44 PM
  #77  
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from the carburetor primer port.
I'm no expert, but I sure don't see any extra ports, capped, or not, on the carbs on my engines. You have pics??
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Old 06-14-2009, 09:02 PM
  #78  
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ORIGINAL: Jake Ruddy


ORIGINAL: captinjohn


The camera angle made it look real unsafe...but I never really reved it near full at all. I used a super heavy firemans glove that protects very well. Yes the mix of glow fuel with gas is good for starting a gasser or a Glow/gas engine. A heck of a good choke or a squirt prime...and most engines fire right up...even on a very cold day with ice on engine!!!! Capt,n

I am sorry but it has nothing to do with the camera angle. That was just a bad example of how to be around an engine turning a prop, let alone an APC (read sharp composite prop). About the time the prop hit your coat I stopped watching. You should have watched it all...and listen to waht is said

I don't care what kind of glove you have on, that's not the way to stop an engine and is a poor example to those who don't know better.Out of over 1,400 = views...you about the biggest and only coplainer!


Other than that, the problem is not a cold engine, it's an engine that has been sitting for months and has a dry carb and in this case a rear carb. That is why I mentioned a squirt /prime...to get things wet
Gee...Jake...I promise to never do it again! This I can say....I have never got hurt with a big gas or glow engines....but the small .25 to .90 I have got some stinging fingers. Capt,n
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Old 06-14-2009, 10:34 PM
  #79  
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I did not get it. How hard is it to open up the cowl and "fix" the carb? Is it called maintenance which should be done when each new seacon starts?

Seriously, I think you need to provide a vacuum to the carb so that the fuel can be drawn to the inside of the carb. This probably can be done by filling the tank, choke on, and establishing a vacuum through the exhaust exit. This is just a theory.
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Old 06-15-2009, 02:29 AM
  #80  
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What we are talking about, as I understand it is carbs that go dry when the plane has not been flown for say, two months; not stored for a long time. I am a fanatic about maintenance, and I still have some carb problems as I am fortunate to have several planes to fly and sometimes one or more may sit for a time before I get around to flying it again. Getting to the field and having to remove the spinner, prop, cowl, etc. and then disassemble the carb is a huge PITA and I am trying to avoid having to do it as I think the others here in this thread are doing as well.

Anyway, for the gentleman that asked for a picture, here is one of a carb I just grabbed out of my junk box. The line on the right is the normal fuel inlet. The line on the left is the "primer port". When used on an airplane, the "primer port" is most often plugged by one means or another. If you run a line from this tube, (unplugged of course) to a fuel dot, you could use a syringe to draw fuel into the carb. This would be working in the same manner as the primerbulb as used on other equipment.

AV8TOR

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Old 06-15-2009, 02:39 AM
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Is there a prize here for the most complicated analysis and solution?!

Just add a few psi of pressure to the tank. Quick, simple and foolproof.

See post #61
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Old 06-15-2009, 02:50 AM
  #82  
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Whatever.... You obviously have never encountered a really stubborn dry carb, nor diaphragms that sometimes only last two months. Besides that, pressurizing the system could cause lines to pop off, or damage the tank and/or stopper.

Just trying to help...

AV8TOR
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Old 06-15-2009, 08:43 PM
  #83  
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ORIGINAL: Wasson

Is there a prize here for the most complicated analysis and solution?!

Just add a few psi of pressure to the tank. Quick, simple and foolproof.

See post #61
I tried doing that (pressurizing the tank) by connecting another piece of fuel line to my vent line going to my tank and blowing into it. Nothing. Then, after I removed the cowl I connected the line directly to where the fuel line goes into the carb. Blew on it again and the same - - nothing would flow - - until I removed the diaphram cover and pressed down on the diaphram. Then air would flow when I blew into the fuel inlet via the tube. So, holding down the diaphram I pumped a bit of fuel into the carb, then she started.

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Old 06-15-2009, 09:12 PM
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ORIGINAL: av8tor1977

Whatever.... You obviously have never encountered a really stubborn dry carb, nor diaphragms that sometimes only last two months. Besides that, pressurizing the system could cause lines to pop off, or damage the tank and/or stopper.

Just trying to help...

AV8TOR
He did not say BLOW IT UP just enough pressure too push fuel trough carb parts....like the little one way flapper valves in pump. Sounds like the most simple and best way yet. But I am sure there are some to stuborn to try something simple. If set up right...a simple pressure pump can fill and empty your fuel tank too. Capt,n
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Old 06-15-2009, 09:23 PM
  #85  
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This has been a most interesting thread so far. Many possible solutions, some report "cures" that work for them....and the surprise is that no one (unless I missed it) has a consistent, repeatable and reliable solution.

After my experience with the starting fluid, and the effort at blocking the vent and squeezing the tank to provide "pressure", about the only thing that I am sure about is that those methods are a hit and miss chance/luck effort.

The check valves in the Walbro's prevent vacumn draw. In fact, a "continuous drip" through a carb is actually a symptom of a bad malfunction of the carb. These aren't like glow carbs.

The "trick" seems to be keeping the pumping system, diaphragm, flapper valves, etc. in their "running state", with all chambers full of gas when they are supposed to be. The nature of the carb butterfly, fuel line, and intake side are such that I don't think we can seal off the carb.

So....the primer bulb is a really great solution, but it doesn't seem to adapt to the carbs on the rear-intake 50cc's. Need more infor for that. How do we retrofit the primer bulb on carbs that weren't designed originally to have one?
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Old 06-15-2009, 11:07 PM
  #86  
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According to this articule (www.drystacked.com/Walbro%20Carburetor%20Theory%20ebook1.pdf, page 7, the 4th paragraph) , the key is to establish a vacuum in the lower fuel chamber to allow fuel to be drawn to the carb. Iwould still think that vacuum can be established via a vacuum cleaner sucking the air at the exhaust port.
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Old 06-16-2009, 05:19 AM
  #87  
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That's a very good article, in a lot of ways. Thanks for posting. It doesn't address carbs like our 50cc class carbs that do not have the "primer pipe", however. After reading that, I tend to agree with your suggestion. Adapting a priming bulb may be possible, or some other device to prime.
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Old 07-21-2009, 11:21 AM
  #88  
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Never Never Never use a vacuum cleaner to draw gasoline, gasoline vapors, or other combustibles. The motor is not designed for use in "hazardous (explosive) environments". People die trying to siphon gas this way.

Also, pump style Walbro carbs have no means to suck fuel though.
ORIGINAL: nonstoprc

According to this articule (www.drystacked.com/Walbro%20Carburetor%20Theory%20ebook1.pdf, page 7, the 4th paragraph) , the key is to establish a vacuum in the lower fuel chamber to allow fuel to be drawn to the carb. I would still think that vacuum can be established via a vacuum cleaner sucking the air at the exhaust port.
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Old 07-28-2009, 12:17 AM
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ORIGINAL: Wasson

Is there a prize here for the most complicated analysis and solution?!

Just add a few psi of pressure to the tank. Quick, simple and foolproof.

See post #61
What you do is blow into the vent tube with your mouth and let blow back and fill your mouth with gas and then you will not have to worry about starting your engine for awhile.
I have over 20 airplanes with gas and Walbro carbs some of them set for years. I do not have these kind of problems . Just squirt some gas in engine some way.spark plug ,carb ,exhaust .May take a couple of times.If you can get to carb needles open them about a 1/4 turn each. Try priming first usually needles will be OK after run a little while. Solder hole shut in choke plate. You do have to change all fuel tubing once in a while.
BCCHI AMA 2500

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