JD 90 Skid Steer Onan motor dilemma

Here are the problems and the various solutions I’ve tried. It’s always been hard to start, especially during the winter. Once I get it started, it will run fairly well out of gear. When I engage the clutch, it bogs down quite a bit. When I start to move, it wants to die. If I take it out of gear, it will usually rev back up. Or, if I choke it about half way it’ll come back to life. I can usually nurse it along for about 20 minutes before it finally dies. After that it won’t start until it has cooled down. When it dies I can hear a sort of bubbling or gurgling sound if I listen to the air filter. To see if I can see the source of the noise I’ve taken off the hose that attaches the air filter to the carburetor. I don’t see any boiling gas or anything. I do see white smoke inside the carb.

I’ve tried the following with no measurable success: Changed the spark plugs (several times), each time they come back black. Changed the points, the condenser, ignition coil, spark plug wires. Adjusted the idle and high speed needles, and adjusted the governor stop. I took the carburetor off and blew it out with compressed air. I did not take the needles and blow out those little holes, maybe I should have. I adjusted the float, which was a bit off and allowed the carb to fill up with fuel. I’ve tried testing the spark plugs, but I may be doing it wrong, because I can’t get them to spark. I take them out and have held them close to the chassis and have also touched the outside of the plug to the chassis. I’ve only done this after it has died, there has never been a spark. Also, I have changed the fuel filter.

After all of this it will only run about 20 minutes, then die. It also seems to be lacking power compared to a year ago. Could there be water or dirt in the gas tank, or could the fuel jets into the carburetor be clogged? Or, could it be an electrical problem? I’m really at a loss and thought that you guys might have some ideas for me to try.

While you have the carburetor in your hand, clean all the passages and jets (but don't bore them larger) and see that the choke closes all the way for starting and opens all the way for running. Sometimes the choke cable sheath anchor comes loose and it won't open all they way.

Check the distributor for loosing gap, due to worn shaft. Check the wiring with a test lamp to see that there's power to the coil after its shut down.

Its quite possible that the fuel line is plugged. Check the carburetor inlet fitting screen. I've seen those so plugged that I couldn't detect 60 PSI air passing through.

Though the long time constant looks more like the gas tank cap vent is plugged.

Try plugs other than Champions so they clean up when running instead of staying fouled once fouled.

Gerald J.