MF 50 Gas backfiring low power

Hello,

I'll start this by saying that I am not a great mechanic. I can follow directions but don't have the intuition of a real mechanic.

So I have a 1964 MF 50 with a gas engine. It has not been run since this winter when I used it a couple of time to push snow. When I ran it this winter, it ran rough and backfired a little but had enough power to push the snow on our lane.

I went to start it yesterday, it started first crank but ran very rough with lots of hiccuping and a couple backfires through the carb but lots of pops and backfires through the muffler. Very little power and not able to drive it at all even after a long warm up.

Here is a short history and maybe folks on here can help me figure out what to do.

Late last summer I was mowing some tall grass when I saw the temperature gauge shoot way up very fast. Before I could reach down and shut off the key, I saw coolant shooting out of the front end. It looked like the seal/gasket on the water pump has blown.

So I took it all apart. Put in a new water pump, new thermostat, cleaned the radiator and got it running again. It ran fine to finish mowing my fields last fall but thinking back, I think it was slowly losing power. The backfiring issue started this winter.

So my thoughts are to drain the gas tank and clean the screens and try new fuel. But I am not sure how to trouble shoot after that? New plugs? Plug wires? Distributor?

I'd sure love some advice from forum members.

Thanks

I've fought a misfiring 3 cylinder Perkins
gas in my 150 for years. Constantly
changing spark plugs, points, condenser,
etc. I put a pertronix coil and distributor
kit on it yesterday and ran a bushog for
about 3 hours. It ran better than ever. I
hope it keeps it up!

I have a MH 50, had issues with low power and ended up doing a full rebuild due to low compression on two cylinders.

Hopefully you are luckier than me. I would clean/check the carb and distributor/points.

I would then check the compression and perhaps do a leak-down test. If you have a valve that is not sealing, you will be able to hear it during a leak-down test.

(quoted from post at 08:13:24 04/24/16) I have a MH 50, had issues with low power and ended up doing a full rebuild due to low compression on two cylinders.

Hopefully you are luckier than me. I would clean/check the carb and distributor/points.

I would then check the compression and perhaps do a leak-down test. If you have a valve that is not sealing, you will be able to hear it during a leak-down test.

Click to expand...

I agree with doing a compression, or leak-down test first to make sure the engine is ok mechanically. The overheating could have caused the head gasket to eventually fail.

I have the same tractor. I would try the easy things first. Process of elimination.

Remove and clean the sediment bowl on the fuel tank and drain the carburetor...then try it

Check the coil spark....half inch and blue...try it.

Pull the plugs...replace with new gaped properly...$10....try it.

Drain and clean the fuel tank....new very clean fuel...try it.

How are the points in the distributor???

It seems unlikely to me that low compression would have come on so suddenly, that usually is a long slow wearing out process...unless a valve is suddenly sticking open.

Thinking back, my MF65 gas (same basic tractor) was backfiring and no power, and I cleaned out the fuel lines, drained the carb bowl and fuel line sediment bowl (let the fuel run long enough to flush the lines) and replaced the plugs. One of those fixed my problem.

X 2 on Hay's comment of flushing the fuel system. That's how they run with water in them from sitting around with little use, catch what drains out and look for water..

Check the ignition timing, make sure the advance is working, make sure you have good spark and make sure the mixture isn"t too lean. Lean mixtures can be caused by things other than the carb mixture screws. Air leakage around the carb metering section ( throttle shaft leakage, cracked or rusted out intake manifold, low float setting, or leaking intake manifold gasket)can lean the mixture also.

Had a lot of luck with Pertronix, myself... Shhhhh... the purists might hear.

Aaron