Massey 135 gas running rough

   / Massey 135 gas running rough #1  


New member
May 8, 2023
Massey Ferguson 135 gas
We have had our tractor that has been in the family since new redone in the past few months and has been running great until now. I was bushing some steep hills and then the tractor started running rough.
It cranks up but doesn’t run smooth. Any suggestions on what could be causing the issues.
   / Massey 135 gas running rough #2  
Does pulling the choke out when it is running help make it run smoother?
Is a spark plug wire touching anything? They can ground out or bleed voltage if touching the engine or other metal.
Another thing you might try is when it start running rough, start spraying WD40 or carb cleaner around the intake, carb, against the block at the intake manifold. If an intake gasket is going bad then when everything warms up it can start 'opening up' which causes it to suck air and warm up. By spraying the aerosol fluid around it it will momentarily suck that in and run fine for a few seconds whch will show you where your air leak is.
   / Massey 135 gas running rough #3  
Birdhunter has all good points to check. Another thing might want to check is the distributor. Being that this was recently restored they had to re-set timing. Theres a change the distributor got loose or bumped and your timing is slightly off now. This is the Continental gas engine right?
   / Massey 135 gas running rough #4  
Before you go doing anything check the quality of the spark, if it is yellow then there's yer problem. Do this before you start messing around with the fuel system. More good fuel systems have been screwed up because of bad spark.
   / Massey 135 gas running rough #5  

I noticed that you mentioned the problem started after steep hills. The MF 135 has a large, flat fuel tank and the sloshing of fuel back and forth may have dislodged debris and blocked the fuel system. Check your ignition first, then consider the following:

1. There's a small filter in the tank directly over the outlet, or at least I believe there was from the factory. I hear talk of these blocking. Mine is missing so can't block, but it allows debris to get down the line.

2. The glass fuel bowl, if you have one, gives an idea of how much fine debris is coming from your tank. Check to see if there's plenty there. If so, consider that the carby might have debri in it.

3. Remove the fuel line from the attachment at the tank/sediment bowl. Turn the fuel tap on and expect a steady stream of fuel. If not, your issue is a blockage above that point. You'll need to remove the tap and investigate.

3. Check the line from the fuel bowl (or tank if there's no bowl) to the carby by removing and blowing it out. Try starting it again. If the problem persists, consider the following.

4. Debris often gets caught in the needle valve on these types of carbys. Checking this involves disassembly for most carbys, hence why you want to have checked the ignition system first. They're not unduly complex, but it depends on your level of skill and enthusiasm. The second point that debris often blocks a carby is the main jet and the idle jet.

I have found algae, paint flakes and a Phillips screwdriver causing issues by following these steps. Hope this helps.
   / Massey 135 gas running rough #6  
If you think any wires are shorting out run the tractor
when its completely dark you will be able to see any
sparks if that's the problem