MF-135 Troubleshooting and Repair Question

I have a 67 MF-135, gas, z134. I have 2 issues:

1. When I am mowing (6ft Land Pride), the tractor runs fine for about 15 minutes then it starts to cut out and will die. It used to be about 30-45 min, but the time is getting shorter and shorter of good run time. When it starts to cut out, if I push in on the clutch so the tractor is only running the mower and no longer moving, then it stops cutting out and powers the mower smoothly. If it happens to be starting to cut out and then I go down a slight hill to where the tractor doesn't have to work to go forward, then the cutting out stops. It did this with my "old" gas tank and with the new one that I just installed. Any ideas on what I can start tinkering with or checking?

2. My gas tank started to rust out and leak so I got a new one. When I got the new one, my sediment bowl assembly would not screw in to the bottom of the tank. I dropped it off at a machine shop and they cleaned the threads and it now screws in nicely. However, when it gets to the point of where it is tight, the assembly is about 180 degrees from where it needs to be...has to be facing a certain direction for the gas line to hook up on the back and the front to be available to turn the gas on and off. I used some sealant when I installed it and just left it 180 degrees short of being tight and deal with a very small leak while using the tractor right now (the yard really needed mowed, but I know this isn't safe). Should I just take this back to the machine shop and explain the angle it needs to face when it's tight and they would be able to shave a slight bit more off the threads to let it go in another half turn to be tight?

Thanks!

Problem #1 sounds like coil. #2 take the tank and the fitting both to the shop or you could wind a few turns of Teflon tape around the fitting before screwing it in.

#1 I've seen points with too close a gap give that symptom. In one case a mounting screw was loose and allowed the points mount to change the gap.

To keep running, you need 3 things. Fuel, ignition, and air. That being said, air is probably the least of the worries.
A few trouble shooting ideas. Try running with the fuel cap loose. This eliminates a tank venting issue. Check for fuel flow. Take off the fuel line at the carb and check flow. (This is my guess for trouble). Make sure to clean the screen in the bowl if so equipped.
The final thought is loss of spark. Coils fail, and it seems they all run until they get warm. But they typically will fail regardless the load on the engine. Same with condensers.

Carry a fire extinguisher. Oh, also, carry a big fire extinguisher. One more thing, be sure to carry a big fire extinguisher.

I'd like to modify my original statement of a Z134, it's actually a Z145, not that it probably makes a difference on the issue I'm having.

I tried mowing with the gas cap loose to make sure it was getting air and not preventing fuel flow. It did not solve the problem and started to cut out and die after a period of time.

I then ordered a new coil, installed it last night, mowed today, and I had the same problem after about 10-20 minutes it would die.

Then I took the distributor cap off, used an emery board to polish the point, slightly adjusted the gap to verify it was .022, then mowed again and it did not solve the issue.

I then disconnected the gas line from the carb, turned the gas on and verified the fuel flows freely and there is not an issue with the fuel flow. The screen also looks fine on the sediment bowl.

Any other ideas? Should I replace the spark plugs or mess with the carb or what should I check next? Thanks for the responses so far, they seemed like good ideas of things to check and try.

Thanks

JR

This weekend I replaced the plug wires, spark plugs, points, condensor, and rotor. This did not fix the issue. Then I took the battery and got it tested, and the test came back saying it needed replaced. The new battery also did not fix the issue and it starts to cut out and die after 10 minutes of mowing. Any other ideas?