'84 marathon pours out overflow

[clickdeath.05]

I just bought an 84 marathon with the 2 stroke engine. It ran fine for the first 3 days but then it started to bog out at top end and pour out the overflow. It increasingly got worse to where it doesnt even start and just pours fuel out of overflow while the generator runs. I have scrubbed the carb clean of all gunk, put on a new fuel filter, new spark plug and new air filter, and replaced gas in the tank. Any ideas on what it could be?

[Heliarc]

Your float could be shot, or somehow got out of adjustment.Take it off and have a good look at it for cracks and shake it to see if fuel is sloshing around inside it.After that, your needle valve or seat could be bad.

To see if it seals at all, take the carb off and turn it upside down.Try to blow into the fuel inlet with your mouth, not a compressor.You might need to hook a small piece of fuel line to it in order to do it properly.You should not be able to blow into it.Turn it right side up and you should be able to blow into it.This will tell you if your needle valve is good or not.So if it passes this test, your float is probably either poorly adjusted, or cracked.If it fails this test, your needle valve could be suspect.

Still, this is not a tell all.this is just to help you figure out where to start looking.If it does ok on the blowing into it test, take the bowl off and examine your float well.Also, take the float off and lay the needle valve down in the seat.Now gently with your fingers, hold the needle valve down and again see if you can blow into the carb.If you can, you should feel the air coming past the needle valve and over your finger.

[clickdeath.05]

Thank you for the advice. I just got it back from paint so it will be a day or two. I will let you know how it goes.

[simple man]

I think " Heliarc " is on the right track! If you have worked on the fuel system, small bits of hose you removed, dirt, fuel deposits, could have caused the needle valve not to seat. It's a good idea after doing fuel system work to crank the engine with the fuel feed line to the carb stuck into a container of some sort, and pump at least a half pint or so of fuel to flush this stuff out before you connect the line to the carb!

[clickdeath.05]

tore the carb apart and found a very small metal shaving stuck under the needle valve. i dont know how i missed that before. the cart starts and runs fine but now, right before the powerband kicks it just loses power and back fires. Now what do you think is wrong. My cousin said it was a possible cracked reed valve??

[Heliarc]

If it's reeds, that's easy to check.Take off your intake(behind the carb)and the reeds will be underneath.They come out in a block and look sort of like the guts in a harmonica.There should be no cracks or chips.Also, on mine I could try to suck through them and they would just about hold vacuum.You'll see how they work once you look at them.Not sure if that's the cause though.A backfire would almost suggest to me the ignition cutting out momentarily, fuel building up, then the ignition comes back and ignites it with a good bang.I used to do this on purpose when I was a little turd just starting driving on carburated cars.I'd shut the key off coasting down a hill, hold the gas wide open, turn the key back on and KABLAM!!.

My wild guess is, first, check your sparkplug.It might be fouling out and dying at high speed.My next guess is that at high speeds, your coil is not able to keep up with demand and is failing.Then as the engine slows a bit, the coil is able to produce spark and makes it backfire.If you have a regular automotive coil around and you can wire it up and secure it, that should be a good test.Or remove the coil and take it to an auto parts store.They should be able to test it for you.

[racin161]

Lack of fuel check the fuel pump pressure.



LOU