140 sometimes runs rough

[septemberfarm]

Does anybody have a suggestion on what might be causing my 1967 IH 140 12 volt positive ground tractor to run great sometimes and then all of a sudden run lousy with no power and an occasional backfire. I just tuned it up , new cap, rotor ,and wires and rebuilt the carb. I also converted the ignition to an electronic ignition, but the problem still occurs.

[Boss Hog]

It should be 12 volt neg. ground. Most likely an issue with trash in the carb. Is the tank clean ? and does it have a good fuel flow?

[septemberfarm]

Thanks boss hog, Your right it is a negative ground, and I'll check the strainer on the tank and post the results.

[dgrapes59]

Septemberfarm,

Welcome to the forum!