Well, I got the switch fixed and the machine will turn over now and start. But maybe some ideas about what's causing the following: Up until recently - for many years - in the cold, a full choke would get it going and then after maybe 45 seconds, a minute, I could push choke in and away I'd go. Now, I have to keep choke open for a long time or it will die. I keep working the choke in and out, fooling with the throttle for maybe 5 minutes or so, until it warms up. During this period it tends to surge a bit - like it's fuel starved. But after it gets fully warmed up, it works fine - full throttle if you want, idle if you want. It's like something expands with the heat (?) and stops an air leak or something. Could I be experiencing gasket deterioration, courtesy of ethanol, that the machine has been drinking the last twenty years? I can still use the thing, but something's not right. Kholer twin with about 1600 hours, well maintained.
- Thread starter firhead
- Start date
It could be ready for a carb overhaul, mostly to clean out all the little passages. Ethanol does cause some problems, but not as much as it gets blamed for, unless the machine sits for more than three months with the same fuel. If you have a fuel filter on it, check it aint partially clogged.
After 20 years or so, it could be anything. As Phil B suggested, a carb overhaul may be a good idea. First you may want to just richen the fuel adjustment a bit for cold weather.
I'm assuming that your Gravely as the Kohler Magnum M18 engine. (Gravely used the M18 engine and derated it a couple of HP.) Before ordering any parts, check to see what carburetor is on your unit. Gravely used both the Kohler and Walbro carburetors, and parts are not interchangeable.
I have two Gravely two-wheel tractors of the same vintage that developed carburetor issues. Both had Walbro carburetors which were unbelievably expensive. I opted to buy aftermarket $25 made in China carbs. They have both worked fine for several years. The one thing you had to watch when ordering one was the choke on the carb. When the carb was used on different types of equipment, the choke linkage was different. You need to make sure the carb you order is compatible with the linkage on your tractor.
It never hurts to read the manuals.
I'm assuming that your Gravely as the Kohler Magnum M18 engine. (Gravely used the M18 engine and derated it a couple of HP.) Before ordering any parts, check to see what carburetor is on your unit. Gravely used both the Kohler and Walbro carburetors, and parts are not interchangeable.
I have two Gravely two-wheel tractors of the same vintage that developed carburetor issues. Both had Walbro carburetors which were unbelievably expensive. I opted to buy aftermarket $25 made in China carbs. They have both worked fine for several years. The one thing you had to watch when ordering one was the choke on the carb. When the carb was used on different types of equipment, the choke linkage was different. You need to make sure the carb you order is compatible with the linkage on your tractor.
It never hurts to read the manuals.
So rather than try and find/install a carb rebuild kit, maybe it would be better to get a Chinese complete carb - cheap, maybe effective, and easier than tearing apart the old one assuming everything fits up. I've got a reprint service manual for the M18/M20 and they reference trouble shooting and adjustments for the Walbro; what's perplexing me is that after it's warmed up it runs perfectly: good throttle response, no misses or smoke, good idle, good power. My original theory was that after 25 years, I had sediment build up in the fuel tank. and with aggressive choking I could override whatever restrictions were a result of this, and once the fuel line and filter were full with my choking technique (after having got cold and sitting over night), I was good to go. So I removed tank and cleaned it out, checked fuel line and filter - and this didn't fix the problem. But here again, when I'm warmed up, I'm good.
After 25 years it is a good idea to replace (rather than check) all your fuel lines. Most fuel tanks have a screen on the outlet fitting, so no amount of choking the engine is going to pull much sediment out of the fuel tank.
Most of the problems I have had with Walbro carburetors on 1980's Gravely tractors have been float needles either sticking or leaking. As I recall (and my memory is not improving with age) the float needle seats on Walbro carburetors were pressed in, not threaded in---so could not be replaced. I recall that the cost of new Walbro carburetor for my 16G was nearly what I paid for the tractor and that was several years ago.
If you take the China route, I advise examining the throttle linkage and choke linkage very carefully before you order a carburetor. I recall that the carburetors for my m10 and m12 engines were available with two or more different choke shafts for different applications. I also recall that I had to slightly modify the throttle linkage on one tractor because the holes on my new China carb were a different size than on the original carb.
Most of the problems I have had with Walbro carburetors on 1980's Gravely tractors have been float needles either sticking or leaking. As I recall (and my memory is not improving with age) the float needle seats on Walbro carburetors were pressed in, not threaded in---so could not be replaced. I recall that the cost of new Walbro carburetor for my 16G was nearly what I paid for the tractor and that was several years ago.
If you take the China route, I advise examining the throttle linkage and choke linkage very carefully before you order a carburetor. I recall that the carburetors for my m10 and m12 engines were available with two or more different choke shafts for different applications. I also recall that I had to slightly modify the throttle linkage on one tractor because the holes on my new China carb were a different size than on the original carb.
Russ from MN
Well-known Member
- Location
- Bemidji MN
If it has adjustments on the carburetor have you tried opening them up a little?
Well, my theory (read 'hope') was that if the fuel supply was being constricted - but not totally cut off - choking it aggressively was
creating enough additional pull to fill the line and filter which would have drained off somewhat last time I shut it off. When the system
was full up now supply would be consistent, hence things would smooth out. Right now, it seems to be pretty good but though I'm no mechanic,
I do know that things don't fix themselves. I have had experiences where simply taking things apart and putting them back together has gotten
things working - but it didn't have anything to do with me knowing what I was doing. Never have had valves checked, never have touched the
carb. Good at oil and filter changes, though.
creating enough additional pull to fill the line and filter which would have drained off somewhat last time I shut it off. When the system
was full up now supply would be consistent, hence things would smooth out. Right now, it seems to be pretty good but though I'm no mechanic,
I do know that things don't fix themselves. I have had experiences where simply taking things apart and putting them back together has gotten
things working - but it didn't have anything to do with me knowing what I was doing. Never have had valves checked, never have touched the
carb. Good at oil and filter changes, though.
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