MF 135 Perkins Gas 3 Cylinder Backfiring no Power

[slhilbert]

I hadn't started my MF 135 Perkins Gas 3 Cylinder for several months. A few weeks ago I started it up and it was backfiring really bad, popping all over the place. I was able to rev the engine at that time, so I revved it up and after a few minutes the pops and backfires stopped and I was able to start mowing down the fields with my rotary cutter. I mowed for probably 1.5 hours without an issue.

The next day I got back on the tractor to continue to mow and it started right up and backfired for maybe 30 seconds and then was fine. I mowed for about 15 minutes and all of a sudden the tractor died. I tried starting the tractor and it was backfiring all over the place again and I couldn't get it to rev at all. Eventually it got so bad, I couldn't even get the tractor to start anymore.

I took the carb off and thoroughly cleaned everything, put it back on today and I can start the tractor and it will idle for a while, but if you try to rev the engine (give it gas) it backfires all over the place. At this point I can't even get the tractor to move as it dies if you try to put it in gear.

I currently have the mixture screw all the way out, which will let it idle.

I am pretty much at a lost and no really a great mechanic, so what are my options at this point? Part of me wants to go buy a new carb and see if I can just call it a day, but at $400 that isn't a cheap option.

Here are a few videos that show the issues.

Thanks for the help!
Stuart

 

[big bubba]

what grade gas do you use? assuming non ethanol? fuel treated as well? surely you've learned by now to use non ethanol in old tractor & small engines. empty tank & purge the system w/good fuel

actually didn't realize the MF135 came with gas model, thought it was only 3cyl Perkins diesel
welcome to the world where diesel & gas ain't what they used to be
& use a good gas stabilizer once it's running smooth... you have a great vintage model. had MFTO35 for 28 yrs on this end. glad yours still operates, best regards

 

[Egon]

Check timing & govenor?

 

[big bubba]

plugs, pts, ign wires as well. though feel it could well be fuel quality related if the machine was running fine months ago, good luck

 

[seville009]

Check your airbox/filter in case rodents chewed up your filter and the pieces ended up getting sucked in.

 

[slhilbert]

Check your airbox/filter in case rodents chewed up your filter and the pieces ended up getting sucked in.

Air box is clean and actually off right now, so that isn't it.

 

[slhilbert]

Since the last post, I have completely disassembled the carb and cleaned it. Drained and replaced the fuel. Replaced the sediment bowl and put new fuel line and filter on.
That got me enough juice to get the tractor very slowly and with a lot of finesse into the garage. The tractor was starting up just fine and idling but still couldn't power it up without it backfiring out of the exhaust only now.

I pulled the distributor cap to check the points. Noticed some metal shavings. When I went to adjust the points I notice the distributor cam isn't turning, which I am pretty sure it needs to be and seems like in all the videos I look at it does. If I manually turn the distributor then I can get it to rotate a bit, but it doesn't continue to turn. This is foreign territory for me. Please advise.

See the two videos that show the issue.

Thanks Again!
Stuart

 

[ultrarunner]

I've had a bad condenser behave as you describe...

The cam must turn when cranking the engine.

I've never had a fuel issue related to backfire...

Either it was a spark issues or once a stuck valve...

 

[George2615]

Since the last post, I have completely disassembled the carb and cleaned it. Drained and replaced the fuel. Replaced the sediment bowl and put new fuel line and filter on.
That got me enough juice to get the tractor very slowly and with a lot of finesse into the garage. The tractor was starting up just fine and idling but still couldn't power it up without it backfiring out of the exhaust only now.

I pulled the distributor cap to check the points. Noticed some metal shavings. When I went to adjust the points I notice the distributor cam isn't turning, which I am pretty sure it needs to be and seems like in all the videos I look at it does. If I manually turn the distributor then I can get it to rotate a bit, but it doesn't continue to turn. This is foreign territory for me. Please advise.

See the two videos that show the issue.

Thanks Again!
Stuart

Yes, that distributor shaft must turn when the engine is cranking. If not, you won't get spark to each plug. I cannot see how it ran at all in your first post if the shaft doesn't turn. Seems like something is broken on the bottom of the distributor shaft. I had an MF135 many years ago but never had to remove the distributor. I'd say the drive gear is broken but you'll have to pull it to check.

 

[slhilbert]

I think me pulling the distributor cap must have been the straw that broke the camels back.

I pulled the distributor and you can clearly see that the gear is all chewed up.

I am assuming the distributor goes into the crankshaft, do I need to worry about the gears in there?

Thanks!
Stuart