m sputters and backfires

Justin Hart · Jan 8, 2010

my m sputters and backfires throws sparks out exhaust. this started happening after i rebult the carb bacause it would flood out. I soaked carb for a week to get all the gunk out and blew out with air. it runs fine sometimes when it acts up if i shut it off and walk away come back in an hour it runs fine again for a while. the wide open rpm doesnt seem to be there like it used to be. I was wondering if my problem was maybe in the govenor? any thoughts?

CNKS · Jan 8, 2010

You probably don't have the connection right between the carb and governor, in the tube between the two. I forget which is which, but one rod has to go into a slot in the end of the other rod.

Red Mist · Jan 8, 2010

CNKS is probably right. Remove carb again and make certain you get the tab(A) into the slot(B) on reassembly between govorner tube and carb.
Mike

james rumph · Jan 9, 2010

If the governor is correct ! Did you but one of those cheap TSC rebuild kits ?

Many of us have made this mistake ,those kits are very poor.

I rebuilt a carb on a M and a Cub and they both ran worse after rebuilding them.

The cub would sputter and back fire.

I went to the dealer and spent the money on the factory rebuild kit and they both run perfect.

The after market parts and "O" rings are not the correct sizes so i quessing there was internal leaks and it was sucking air causing a lean condition.

Stick with it there are really nice people on here that will get to the bottom of it.

P.S I have found that the cheap carb cleaner in the can doesn't work like Gumout does, it may cost more but it does work well.

rustyfarmall · Jan 9, 2010

Don't think so. If that tab is not in the slot, the engine will go wide open and the throttle will have no affect on it.

That carburetor needs to come back off. Double check the float height and make absolutely certain that the float is not hanging up on the sides of the fuel bowl. Also, make sure the main high speed idle adjustment is set at a minimum of three turns out.

David G · Jan 9, 2010

You might be missing the venturi, if it is like the carburetor on the H. I had the same issue and found it in the carb cleaner basket.

David G · Jan 9, 2010

Disregard this if it runs right some of the time.

Red Mist · Jan 9, 2010

Hmmmm! Sometimes runs good; sometimes runs bad. Let me see here.....
1) Check with flashlight for junk in bottom of gas tank at pick-up. May be blocking flow intermittently.
2) Coil beginning to break down?
3) Air leak that developes when something (manifold, carb base) gets hot and expands?
4) Bowl gasket: The two tiny holes in the middle will line up, or not, depending upon orientation of the gasket. Check. You may need to turn the bowl gasket over.
mike

james rumph · Jan 10, 2010

Dave:

We were running one of my toys at Milan Dragway a few years back. Well i had the carb on the bench in the trailer and got to flappin my gums.

Well they were calling classes to the staging lanes and there sat the carb !!!!!

Well we got it all back together and made that round "but" e.t fell of 2/10 why?

When i got back in the trailer i noticed the main jets sitting on the bench.

I ran it with out main jets , this was methanol motor. I still laugh that the motor handled all that fuel and only dropped its e.t buy 2/10.

Lesson learned...

m sputters and backfires

Justin Hart

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CNKS

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Red Mist

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james rumph

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rustyfarmall

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David G

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David G

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Red Mist

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james rumph

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