Gas/Carb/Methanol

Gary Mitchell · Sep 5, 2015

I recently rebuilt a Marvel carb and put it on one of my 77s. Yesterday it acted like it was out of fuel. I took the carb off and took it apart. The needle, (rubber or neoprene tip) was a little bit stuck in the seat and the inside of the whole thing was a little black looking except for the brass parts which were white. I rinsed and blew it out then put it back on where it ran fine but I don't expect that to continue. What do you suppose the problem is? (it was "new" gas) gm

old · Sep 5, 2015

Do you turn the gas off when you park it?? If not yep this new crap gas maybe the problem

Gary Mitchell · Sep 5, 2015

Old, gas ran good to the carb, that's why I knew to pull the carb and look in it. I think I'm gonna completely re-clean the carburetor and run up the road and get some old fashioned gas w/o the alcohol in it. It sure has me scratching my head though. I use this same gas in everything else. gm

UncleTom · Sep 5, 2015

Also clean the needles's seat with a Q-tip and carb cleaner.

rustyfarmall · Sep 5, 2015

Did the tractor set for awhile with gas in the tank before you got it running again? Sounds like maybe there was some gas in the tank that was starting to varnish up.

old · Sep 5, 2015

Well yes the gas should flow good to the carb but if it sits in the carb and the alcohol absorbs water from the air and then evaporates yes it will leave what you found behind in the carb and cause carb problems

Gary Mitchell · Sep 5, 2015

This gas was "new" a couple of months ago and I had the tank off and looked in it. It was still well galvanized except for a spot or 2 that was beginning to show rust. When I went back out there it wouldn't even flow from the tank to I removed the sediment bowl from the tank. It had a bunch of wet powdery looking gray stuff in it and the intake screen was plugged in the bottom with the same stuff. ALSO the part of the gas cap that goes in the tank is coated with the same looking white junk that the seat and jets were white with. I'm purging everything and getting some new %100 gas to start over with. Hell of it is I use gas from the same batch in my mower and Hank my 8N w/o a problem. Guess I'll keep plugging til it runs. Thanks for the ideas all of you. gm

rustyfarmall · Sep 5, 2015

(quoted from post at 13:35:43 09/05/15) This gas was "new" a couple of months ago and I had the tank off and looked in it. It was still well galvanized except for a spot or 2 that was beginning to show rust. When I went back out there it wouldn't even flow from the tank to I removed the sediment bowl from the tank. It had a bunch of wet powdery looking gray stuff in it and the intake screen was plugged in the bottom with the same stuff. ALSO the part of the gas cap that goes in the tank is coated with the same looking white junk that the seat and jets were white with. I'm purging everything and getting some new %100 gas to start over with. Hell of it is I use gas from the same batch in my mower and Hank my 8N w/o a problem. Guess I'll keep plugging til it runs. Thanks for the ideas all of you. gm

The tank may have looked clean inside, but there was something in there that the new gas dissolved. Either that or someone sabotaged your gasoline supply.

RandyB(MI) · Sep 5, 2015

Didn't know they galvanized the inside of tanks but if it is it sounds like it's breaking down and you are seeing zinc powder or whatever the tank was coated with at sometime.

jacks · Sep 5, 2015

Gary, in a vented fuel system such as older tractors had, when humidity is high outdoors your fuel tank will get high humidity air trapped in the air space, and the ethanol will absorb the water from the air. As the ethanol/gasoline/water mixture sits a weak acid is formed. The galvinizing coating inside the tank contains zinc, which is one of the 'least noble' metals- in other words zinc (also used in carburetor bodies) will sacrifice ions to the acid solution and literally be converted to a zinc oxide paste over time. I live in a humid climate, and I learned the hard way that ethanol gasoline and older carbureted engines is a bad combination. I have disassembled several small engine carburetors that were all coated with the white-grey paste that you describe. The carburetor bodies were pockmarked with holes inside, and not rebuildable. I run ethanol gasoline in a 90's jeep with a nonmetallic fuel tank, nonvented fuel system and fuel injection and don't have any trouble. My advice is to drain the fuel tank, clean everything up, rebuild the carb and stick with non ethanol gas. A little stabil in the fuel tanks keeps the gasoline useable for up to a year or more.

Gary Mitchell · Sep 5, 2015

Thanks Jack. gm

rustyfarmall · Sep 6, 2015

(quoted from post at 18:32:09 09/05/15) Gary, in a vented fuel system such as older tractors had, when humidity is high outdoors your fuel tank will get high humidity air trapped in the air space, and the ethanol will absorb the water from the air. As the ethanol/gasoline/water mixture sits a weak acid is formed. The galvinizing coating inside the tank contains zinc, which is one of the 'least noble' metals- in other words zinc (also used in carburetor bodies) will sacrifice ions to the acid solution and literally be converted to a zinc oxide paste over time. I live in a humid climate, and I learned the hard way that ethanol gasoline and older carbureted engines is a bad combination. I have disassembled several small engine carburetors that were all coated with the white-grey paste that you describe. The carburetor bodies were pockmarked with holes inside, and not rebuildable. I run ethanol gasoline in a 90's jeep with a nonmetallic fuel tank, nonvented fuel system and fuel injection and don't have any trouble. My advice is to drain the fuel tank, clean everything up, rebuild the carb and stick with non ethanol gas. A little stabil in the fuel tanks keeps the gasoline useable for up to a year or more.

I've been rebuilding carburetors for many, many years. I've found that white, powdery substance in many carburetors, long before there was such a thing as ethanol. Also, the gas tanks on the letter series Farmalls ARE galvanized inside. I've owned 2 Hs and and M for a good 17 years. Since I have owned those tractors there has been nothing but E10 put into them, and neither of them has ever exhibited any signs of that white, powdery stuff, nor is there any indication of the galvanizing starting to deteriorate. And yes, it gets to be rather humid here in Iowa also.

fixerupper · Sep 6, 2015

I have found this white powdery stuff in old carbs that haven't had gas in them for 40 years. I remember seeing it more prevalently in lawn mower carbs many years ago and only in carbs that have been sitting dry for a long period of time. If ethanol was causing me problems somehow I would be the first to quit using it but it just doesn't cause me any trouble in my old tractors, even the ones that sit a year with it in the tank. Here in Iowa low humidity is 50%, high humidity is 100%. What it averages, I don't know. It doesn't average as high as eastern coastal areas I will admit but we do get a good amount of condensation in our tanks

Gas/Carb/Methanol

Gary Mitchell

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old

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Gary Mitchell

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UncleTom

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rustyfarmall

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old

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Gary Mitchell

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rustyfarmall

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Gary Mitchell

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fixerupper

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