Fab a diaphragm for a small engine Carb.

[Treemonkey1000]

Most of the carbs are fairly similar from those size engines. I have salvaged carbs from other mowers and things to use for replacing carbs. Sometimes you may have to come up with a linkage for throttle or governor.

 

[Iplayfarmer]

OK, Scratch the nitrile glove idea. I tried it several different ways with no improvement. I tried it with the diaphragm, without the diaphragm, cut the flaps out of the nitrile, in front of the diaphragm, behind the diaphragm, on both sides of the diaphragm. In all instances I got better fuel suction with just the plain old broken diaphragm.

I can still see air and fuel leaking out from around the diaphragm, so I know that is a problem.

Tomorrow I'm off to see the small engine repair guy to see what he can do for me.

The good news is that when I drop a teaspoon of fuel into the spark plug hole the thing runs like a top for a few seconds.

 

[tlbuser]

Tomorrow I'm off to see the small engine repair guy to see what he can do for me.

The good news is that when I drop a teaspoon of fuel into the spark plug hole the thing runs like a top for a few seconds.

It was worth a try. good thinking. Next, if you can't get a pump diaphragm might be to move the tank above the carburetor, then it wouldn't need the pumping action.

 

[RavensRoost]

These guys may have it:

CM Small Engines
We carry obsolete parts for Homelite, Poulan, McCulloch, Briggs, Tecumseh and ATV's. Any 2 cycle or 4 cycle parts. We also carry Efco brand parts, Homelite trash pumps and parts for pumps. As well as Oregon chainsaw parts and bars. Visit us at cmsmallengines.net - Small Engine Parts Inventory For Sale MURRAY PARTS,TECUMSEH PARTS,MTD PARTS More.... or call 1-877-280-1624

RavensRoost

 

[border collie]

Innertube?

 

[Iplayfarmer]

Innertube?

I actually had the innertube sitting on the table ready to cut it, but I'm not sure how well the rubber would hold up to the gas.

 

[Iplayfarmer]

Strike 2...

I went to the local small engine repair guy. He put quite a bit of time into looking for the carb parts, but came up empty handed. He even went page by page through his book and didn't find anything like it.

I looked at the carb, and it's a TK carb. I looked up TK carbs. I didn't see anything that was similar to the diaphragm that I have.

I wonder if there's some way to re-surface or repair the diaphragm I have. You can see in that third picture where the surface of the diaphragm is torn.

 

[Patches]

I believe those elongated button looking thingys in the voids of the diaphram are actually valves that close off and open fuel channels. When one is closed, the other is open to fuel flow, and they are driven by engine vacuum(sic), or more precisely, by crankcase pulses caused by piston movement.The reason the nitrile fix didn't work was that the nitrile didn't move with the original diaphram, but remained against the carb body

 

[Treemonkey1000]

Those are flapper valves for fuel flow similar to the old floats in carbs that would shut off a full bowl of fuel. They need to be flexible enough to move with the small amount fo vacuum created in the carb and still seal. Inner tube would be too thick.
There has to be enough similar carbs that would fit that bolt pattern to come up with another carb that will work. I have done that on Chainsaws and mowers.

 

[Danno1]

I actually had the innertube sitting on the table ready to cut it, but I'm not sure how well the rubber would hold up to the gas.

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I believe an inner tube is made of butyl rubber, which is not resistant to gas.

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