MF 135 gas Fuel Shutoff Solenoid

[kburton]

Tractor cranks but won't start. It fires but doesn't run with a shot of ether. It has clean fuel and the Zenith carb (model ?) was rebuilt and ran a few years back but hasn't been run i years. I got the carb off and the first thing I did was bench test the Fuel Shutoff Solenoid. The needle valve moves free. I energized with 12v and nothing happened and the ohm meter shows a dead short. Is this it or should I go through the rest of the carb. Will this run without the Solenoid?

 

[Jerry/MT]

If it's a gasser I'm surprised it has a fuel shutoff solenoid since you can stop the engine by cutting off the primary ignition circuit. It must me a" farmerized" unit that somebody added because of a leaking float valve in the carb so you don't need it. If the valve is normally closed and energizing it doesn't cause it to open then you won't be getting any fuel. Since you require a good spark, the proper fuel/air ratio, and the correct timing to start a spark ignition engine and one of these elements is missing (fuel) the engine won't start. Since it hasn't run for awhile, you'll need to make sure all three are correct to get it to start.

If it still has a tank valve/sediment bowl, you can shut the fuel off manually if the float valve leaks.

 

[kburton]

I disabled the Fuel shutoff solenoid by cutting off the needle valve and putting a shutoff valve in the fuel line. Now it fires up immediatly on cranking with the throttle on full and no choke. It comes up to about 1500 rpm but dies when the starter disengages. I took the carb apart and all the ports seem open when I shoot carb cleaner through them. The float has no holes but I'm not sure the Needle Float Valve operating properly. It behaves exactly the same before and aftr I took it apart. I think I'll get a rebuild kit and see what happens then. Is there any vacuum on this engine? I didn't see a line anywhere.

 

[zslnk]

The shutoff solenoid was part of the tractor design. I suspect it is there to prevent dieseling or so that the overhead gas tank didn't fill the engine with gas if the float leaked. They are expensive to buy, too bad you cut it up.

 

[Kenneth S]

The shutoff solenoid was part of the tractor design. I suspect it is there to prevent dieseling or so that the overhead gas tank didn't fill the engine with gas if the float leaked. They are expensive to buy, too bad you cut it up.

Why??
Mine never had one, works just fine, just cut the fuel off at the tank when you are not using it. Since its a updraft carburetor it will leak fuel out where the choke, and throttle shaft is well before (if ever) it reaches the engine.

 

[zslnk]

So it doesn't diesel or run on after you kill the ignition or ignite unburnt gas in the hot muffler then. Good point about the up draft.

 

[kburton]

I got it running today. The problem was in the wiring. When I started working on it I couldn't find a key so we put another 3 pole ignition switch on it. When I quit engaging the starter it wasn't getting any power to the coil. Hopefully when I find a key for it I'll put the old switch on and it will work. It spit and sputtered for a little while but I drove it around and it ran and drove pretty good. I'm going away next week and bow season just started but I'd like to get started working on it. It has a funky front end loader frame under it and a home made canapy on it but all the sheet metal is there and in pretty good shape. I'd like to just take off all the sheet metal and steam clean the grey parts then sand and paint the sheet metal and put it back together. Sounds easy.
zsink - I wouldn't mind seeing some pictures of yours. I'll put some pics up soon.