QuestionDear Arnie;
I have had this great tractor 5 years. It has a three cylinder gas engine with the power steering option. Two seasons ago replaced radiator and water pump. Over last month this tractor has begun quitting in the middle of the field after 40 minutes to one hour of use as I brush-hogged tall grass. It has been very hot weather. No choke or throttle adjustments can keep it going when it gets this symptom. After it sits for about 20 minutes it always starts right up so I can get it back to the barn.
I replaced the three spark plugs and the coil in case there may be a weird heat related fault. No change, though, it still quits after an hour or so.
I do notice that when it cranks right after it quits that there is no dark exhaust as there usually is on starting. I at first thought this meant no spark, now I think if means no gas getting to engine, but that is a guess.
I admit my old fuel filter is dodgy and may not being doing a good job, but the glass filter jar always seems to have gas in it even when it stalls. I blew out the tank-to-gas filter gas line twice (it was easiest to reach) with no cure. If you can't help me I will next take the carburator off and clean it and the gas lines up. (when it happens again and I take the carb's float bowl nut out and find that gas is draining from the float bowl, will that rule out carburator problems?)
Have you ever heard of this behavior? Can you direct me to where I should look? Carburator? Valves (my old compression testor was hard to hook up to these recessed spark plug holes but the three cylinders seemed to have equal and adequate compression). I am stumped.
Thanks very much for any advice you can offer.
Gary in Drexel, Missouri.
Answer You could either do like you said and check if there is fuel in the carburetor after it dies, or check if there is spark by removing a spark plug wire and holding it close to the engine to see if a spark jumps while trying to restart it. You can also use an inductive timing light to check if there is spark as the engine starts to die. If the timing light quits flashing, there is no spark. Since you have already tried a new coil, the condenser might be bad. If there is still spark as it dies, then you know for sure it is a fuel problem. If there is a restriction in the fuel tank outlet, the fuel flow may not be able to keep up with demand. Even though you blew out the fuel line, you need to check the flow from the tank. Remove the fuel line from the tank or remove the drain plug from the carburetor and let it run for awhile to see how much fuel runs out and how fast. It has to run full stream, a small dribble is not enough to supply the engine under load. They like to plug up with dirt inside the fuel shut off valve under the tank.
