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Evo 58 fuel blocked somehow

Old 01-06-2008, 01:28 PM
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FlooredCOBRA
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Default Evo 58 fuel blocked somehow

Last time I flew I noticed the engine running kind of lean. I landed and backed out a little but did not fly again. I wasn't till few months later I went to fly again. Something is blocking fuel i believe.

Here is the problem. I set choke and prime engine it pops and spins over like normal. I then open choke and flip over and normally it cranks up first or second flip. This time it did not. My arm about fell off I flipped it so much. If I go to choke it again it does the same thing. It fires up for a second, i remove choke and again it wont crank up. I checked he fuel filter but it was all clean. No debris. My question is what do I have to remove to clean the blocked portion out? The whole carb I assume and what needs to come aprt to get to where i need to get to for cleaning.

A buddy if mine thats into dirt bikes mentioned that it may be the jets or reeds forgot which he said but may dirty. But I have no idea where they are or how to get to them.

Any ideas what could be causing engine to just fire once then nothing once choke is open? I beilieve the clogged was minimal but effective last time i flew causing engine to run lean. No its to point to where its not working at all due to blockage.
Old 01-06-2008, 03:02 PM
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pe reivers
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Default RE: Evo 58 fuel blocked somehow

Two things come to mind:

Inside the Walbro carb, underneath the cast cover (single screw) is a fine mesh fuel filter. That should be clean. If it is not, that is a sign that your fueling system allows dirt in. Anyhow, clean that mesh filter well.

There also might be a intake membrane issue. If you take the carb and karb block housing off the rear cover, you can check the carbon membranes. They will not ly flat on the housing, but that is no big deal. Check for frayed or broken petals, and replace as required.
Old 01-06-2008, 11:59 PM
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FlooredCOBRA
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Default RE: Evo 58 fuel blocked somehow

would carb cleaner be safe to clean it with or would it attack the mesh? i really dont see anything on it but it is pretty oily and the holes are gummed. It has same color throughtout but seems like i should be able to see through the holes in mesh.
Old 01-07-2008, 05:14 AM
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pe reivers
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Default RE: Evo 58 fuel blocked somehow

You indeed should be able to see through the mesh. It is bronze, so cleaners won't hurt it.
If the fuel gums the mesh, maybe get better gas? In MVVS engines, only premium gas should be used.
Old 01-07-2008, 05:36 PM
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Default RE: Evo 58 fuel blocked somehow

pe reivers,

Thank you for such a quick responce first off. I am a little unsure that we are talking about the same part so I am attaching a picture. I want to make sure I am going to clean or have the right part. This is the section that is held in with one screw. I think this may be the bladder section though.

I will change my fuel type as well. I have been running the normal 87 octane.
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Old 01-07-2008, 06:19 PM
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Default RE: Evo 58 fuel blocked somehow

If you take off the valve flapper membrane, you will look right into the little well with the mesh strainer.

87 octane for MVVS??
Chills run down my spine. I can hear the engine crackle over here in Holland. 90 pump octane (PON) is the lower limit.
Old 01-07-2008, 06:28 PM
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FlooredCOBRA
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Default RE: Evo 58 fuel blocked somehow

Haha. okay point taken i wont use 87 anymore. OKay I pulled the black membrane off and you was right. there was debris inside. It looks to be sawdust. It is not completely clogged but this is not good having as much as I do. Here is how it looked. I will clean it out and give it a shot again this time with real fuel!

Thanks for your help!
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Old 01-07-2008, 08:48 PM
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Default RE: Evo 58 fuel blocked somehow

quick question, how do i go about cleaning that filter? I dont want to use the cleaner and push any debris through the filter deeper. Is there anyway I can shoot the cleaner from behind to get the debris to shoot outwards instead of further into the carb?
Old 01-08-2008, 07:04 AM
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pe reivers
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Default RE: Evo 58 fuel blocked somehow

Pry the strainer out for cleaning. Take good care not to get any dirt or lint in the well.
Debris in there is a sign that your fueling system needs to be improved. No fill t-lines in the fuel draw line, and a good filter on the tank clunk is needed. This is about the most common failure mode in gas engine operation.

Alternative solution: use a pleat paper gas filter (available in car shops) in the carb fuel draw line. The line between carb and filter should have no T or anything else, and should never be disconnected for fueling etc.
Old 01-12-2008, 05:29 PM
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Default RE: Evo 58 fuel blocked somehow

Sorry for getting back so long been working out of town. I just now got to the carb screen all clean and back together. I have a fuel filter but it is not the paper pleated kind. It was a Dubro and it has a plastic like screened mesh. I will change out to the paper kind.

I have a question off subject though. My engine is mounted inverted and at that angle the carb is angled downwards. My plane is a tail dragger so it points down even more. Would it be okay to spin the blue back plate so that the carb points in an up angle? Reason I ask is when I go to prime with choke on my fuel drips out of carb. I was thinking by rotating the back plate and having carb point upwards it would hold the fuel in carb when choked and allow for faster starts. As of now it works fine but I just notice fuel dripping and was curious if this would work.
Old 01-12-2008, 07:27 PM
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Default RE: Evo 58 fuel blocked somehow

Your engine will start better if you do.
To simulate the situation, I have rotated the carb on my test stand to point down. I can however not reenact the posts of some users.
My test engine starts first flip without choking if started within two hours of the last run. My idle needle setting is rich, which helps a lot in starting.
Old 01-13-2008, 10:26 AM
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FlooredCOBRA
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Default RE: Evo 58 fuel blocked somehow

Okay so no problems by rotating the carb. I will spin the backplate and put back together. I always been curious on this and now good to know it will help.

Thanks for the fast reply!
Old 01-13-2008, 12:01 PM
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FlooredCOBRA
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Default RE: Evo 58 fuel blocked somehow

I just tired to remove the back plate. It is pretty snugg. Do I have to heat the engine to get it loose? To bad I cant change the angle of the carb by just flipping it over.
Old 01-13-2008, 06:23 PM
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pe reivers
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Default RE: Evo 58 fuel blocked somehow

Just wiggle and pull. Do not rotate!!!!!!! It is not THAT snug, but the rubber seal may be stuck a bit, so take your time.
Old 01-13-2008, 07:28 PM
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FlooredCOBRA
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Default RE: Evo 58 fuel blocked somehow

Oh okay thanks, I wanted to make sure I wasnt going to mess up anything. I will work at it.
Old 01-13-2008, 10:27 PM
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Default RE: Evo 58 fuel blocked somehow

Okay everything is back together. That back plate was snug as hell let me tell you but I finally got it out with help of my son. We had to wiggle up and down little by little but it all worked out. I can see right off now that my carb is now level with all three wheels on ground. Before it was angled pretty good pointing down. It took me about 8 flips to get it to prime with choke on. But after I got a pop it would fire right up. Then every time right after no more priming was required. So having my carb nice and level will be even nicer to start.

Thanks for all your help and for such fast response!

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