Massey Ferguson 135 Perkins engine runs rough

My MF135 Perkins engine is running awful. I drained the fuel tank, cleaned the carburetor, replaced the fuel filter, clean the sediment bowl and screen, changed the plugs, changed the points and condenser, replaced the plug wires, changed the distributor cap and rotor. I checked to compression by putting my thumb over the spark plug hole and all cylinders blow my finger off with force as i crank the tractor.

The only way it run smooth is by running on full choke at full engine rpm and feathering the choke in and out to keep it going. This works with the tractor stopped or driving it. It seems to backfire a little (air coming back thru thru the air filter. It does not stall out, just misses, and lacks power when the engine misses.

Some more details. It starts easy, seems to be missing on one cylinder, sometimes 2 at startup, then the miss comes and goes. Ay times only runs on one cylinder. Cylinder 1 seems to be firing hot, the plug porcelain is white!! Cylinder 2 and 3 are sooty looking. I changed the plugs a second time purchasing Autolite plugs they recommended. I gapped them at .025", points gaped at .022".

I reallyy need some help figuring this one out. Because it runs good with a full choke being feathered in and out it does not seem like a valve problem. Do you think it is a compression/vave issue.

The tractor does not burn oil. The tractor sat in the barn, dry and was not used for 1-1/2 years. When I fired it up after sitting this long it ran great for 2-3 minutes. Then I drove it out of the barn, it started to miss, and it has not run smooth ever since (unless the choke is feathered.)

Has anyone had problems like this on their MF135 3-cylinder Perkins tractor? I NEED HELP!!! Mark1031

but pulling the head seems

Sat for more then a year not running is not good. Did you at the time you got it just pretty much fire it up or did you do something like an ATF treatment to make sure it did not have stuck rings?? Running rough can be a number of things. Low compression due to stuck rings and or sticking valves. Poor spark or carb problems. Spark need to be a good blue/white that jumps a 1/4 inch gap at the center wire of the distributor cap and at the plug wires. As for cleaning the carb one need to soak it for 24 hours or so blow it out spray it out and poke all the passageways out.

Your description of the plugs seems to indicate a slight intake leak on #1. Added choke gets #1 better fuel so it fires and over fuels 2 and 3. Try spraying some carb cleaner around the intake while it's missing. If the miss comes and goes it could also be a bad intake valve sealing and not sealing as it rotates. I've had that on my Farmall M

For a good compression check you really need to use a gauge. Doesn't take much to blow a finger off the port.

Does that model have a fuel pump?

If so, disconnect the output to the carb, direct the flow to a container. Crank or start the engine, see what kind of flow you get. Should give a full stream, pulsing flow. If slow flow, dribble, air in the stream, likely the pump is bad

If the pump checks good, or there is no pump, remove the drain plug in the bottom of the carb. It should give a full stream and continue to flow (continuous flow when cranking if fuel pump equipped). If no flow or flow slows to a drip, there is not enough fuel in the carb bowl to run. Some carbs have a screen in the fuel inlet fitting, be sure it is clean.

If there is fuel in the bowl, and it still requires full choke to run, check for vacuum leaks. Not sure how the intake is configured, if it is siamesed to the exhaust it could be burned through internally. A vacuum gauge will be helpful diagnosing vacuum and valve problems. Another test, remove and ground the coil wire, opemn the throttle, hold your hand tightly over the air in of the carb, have an assistant crank the engine through. You should get a steady, firm vacuum against your hand, and be wet with gas. If little or pulsing vacuum, there is a vacuum leak or valve problem. If vacuum and no gas, there is a carb or fuel delivery problem.

You may want to revisit the internals of the carb. All fuel must pass through the main jet. Be sure the jet is clean and the adjustment needle is backed out about 2 turns. carb sitting with old gas can clog to the point of needing the passages scraped out with a wire to remove dried deposits. Get this right, fuel in the bowl, the emulsion tube in place in the venturi, and the carb will at least work well enough to run.