I purchased a used 1968 JD 3020 gas tractor with a Zenith carburetor last spring and finally had it out on the road last weekend. After running the tractor a few miles and up to temperature (but not running hot), the tractor would run fine but I noticed the engine would start to spit and sputter when going up hills. Running on flat road or downhill there was no problem.
I started to observe closer how it was running and found the following:
Running at full throttle, 2000 to 2200 RPM and going uphill the engine would start to spit and sputter and RPM would drop the point of almost stalling (like someone shut the engine off). When the engine got to the point of almost stalling, I would push the clutch in and reduce the throttle to 1500-1600 RPM and the engine would seem to recover and come back alive. I down shifted to get up the hill and the tractor seemed to handle it ok and maintain RPM up to the point of about 1800 RPM. If I throttled over that it would start to spit and sputter again.
My thinking is the gas filter is probably getting plugged and starving the engine for fuel. When climbing the hills under more of a load it wasnt getting the fuel it needed and started stalling. If this was an electrical issue (i.e. lack of spark), my guess would be the engine would load up with gas and when the spark came back would possibly backfire?
I will be replacing the gas filter and testing the fuel pump pressure this week. As well I will be checking the screen at the inlet of the carburetor and cleaning as needed. Ive also got new spark plugs I will be installing as well since its not known when they were last changed.
My question is, am I on the right path with this and is there anything else anyone can think of that would be good to look for?
I started to observe closer how it was running and found the following:
Running at full throttle, 2000 to 2200 RPM and going uphill the engine would start to spit and sputter and RPM would drop the point of almost stalling (like someone shut the engine off). When the engine got to the point of almost stalling, I would push the clutch in and reduce the throttle to 1500-1600 RPM and the engine would seem to recover and come back alive. I down shifted to get up the hill and the tractor seemed to handle it ok and maintain RPM up to the point of about 1800 RPM. If I throttled over that it would start to spit and sputter again.
My thinking is the gas filter is probably getting plugged and starving the engine for fuel. When climbing the hills under more of a load it wasnt getting the fuel it needed and started stalling. If this was an electrical issue (i.e. lack of spark), my guess would be the engine would load up with gas and when the spark came back would possibly backfire?
I will be replacing the gas filter and testing the fuel pump pressure this week. As well I will be checking the screen at the inlet of the carburetor and cleaning as needed. Ive also got new spark plugs I will be installing as well since its not known when they were last changed.
My question is, am I on the right path with this and is there anything else anyone can think of that would be good to look for?
