1974 MF135 Gas running rough

[LABanker]

Fellows, I'm looking for a little help here. I have a 1974 135 Perkins three cylinder gas that belongs to my dad and I'm trying to get it running for him. Some history on this unit. Purchased new by my uncle in 74'. Sold to my dad a few year later when my uncle became unable to keep his farm up. Used for many years around my dad's place. Less than 1000 hours but not in the best of shape as he's not much on PM with his stuff. Began running bad some years back and I rebuild the Zenith carb. Not much better. Along came a storm and knocked down a large tree on his hay shed/barn under which was this tractor. Fast forward ten years. I decided to remove the tractor out from under the collasped building and get it running again as it appear he never was going to get around to it. He has several other tractors and could do without this one. Not it terrible shape. bent up the sheet metal, creased the radiator, bent up the fenders etc.... Tires held air and I trailered it to my house. Replaced all hoses, fluids, filters and tried to start. No fire. So I replaced points, condenser, coil, plugs, wires, ignition switch. Darn thing started right up and ran great except for getting plugged up from gas tank and filter bowl every few minutes which were in bad shape. Replaced tank, bowl and filter assembly going to carb. Fuel filter as well. Over the next several days cranked and drove around the house and idled for probably 30 minutes at one time. Running perfectly. Oil pump, water pump all working fine. Took it back to my dad's house and told him to use to move hay around on his rear three point lift for a couple of weeks and lets see if it has any bugs we need to work out. Left all sheet metal off. He called me a day or so later. Appears he picked up a roll of hay and headed to pasture. Got off and started to open the gate and it died. Forgot to open valve on bowl filter. He got more gasjust in case, opened up the filter and it cranked but was running terrible. I came over a few days later and its running just like it was ten to twelve years ago before the barn fell on it. Dajavu Some points to consider.

1) Will crank fine if you pull choke out 60%. Start turning over and then pull full choke. Fires up almost immidealty. Push choke back to say 60% and it will stay cranked but only at about an idle. Try to give it gas and it starts raising ****. Backfiring and then dies. Push the choke in and it dies.

2) Based on info found here. I have 10.5 volts to positive side of coil, and running a jumper from positive side of battery to coil does not help. Battery's not in the best of shape. I have 10.5 volts across coil with points I'm guessing in the closed position and 0 volts otherwise. When running it drops to about 3.4 volts and stays there. I know the timing's a little off as I attempted to time the first time I got it running a couple of weeks before and could not read the marks well until I wire brushed them off. Was running pefect when I first cranked it thought so I'm pretty sure its not a battery or timing problem.

3) Went ahead and took carb off and checked it all out. In clean shape. No residue, dirt, plugged jets etc... One strange thing thought. If you pull to full choke and try to crank it will flood and begin dripping fuel out of bottom of carb. Have to start at less choke.

I'm not sure whether I need to be focusing on the ignition or the fueling system. Any ideas that might help?

Tks

 

[WilliamTO-35]

The obvious problem would be starving for fuel without the choke pulled out.
If there's a drain plug on the bottom of the carburetor float bowl, remove it to see if the float needle is allowing plenty of fuel to pass through. Make sure there's a new inline fuel filter installed. You might be using gasoline with ethanol added, and your fuel line wasn't made for those fuels, and is gumming up the carburetor. If you have a cork float in the carb, the coating may be coming off due to ethanol. Make sure there's no fuel inside your floats if they are hollow brass. If you still suspect the carburetor, rod out any fine orfices with thin wire, and blow them out with compressed air. An engine with a weak ignition will also run on a rich fuel mixture, but not on a normal mixture. I've had a bad ignition condenser cause similar problems. The engine would start and run at idle, but trying to open the throttle would cause backfiring and stalling. If it has a conventional ignition system ( not electronic) recheck the ignition points , try another condenser, try another ignition coil. Check the spark plugs and plug wire connections. Make sure there's no moisture condensation inside the distributor cap or on your spark plug wires. That will cause backfiring . Perhaps the ignition timing has moved due to a loose distributor clamp bolt. Good luck !

 

[Gale Hawkins]

Sounds like the battery had a bad cell too?

 

[Massey_lover]

if you're going to clean out your jets, take a piece of automotive electric wire, strip about an inch on one end, and then separate the individual strands of copper wire. You only want one little wire to poke through your jets. Using steel wire in a brass jet removes brass from the sides of the hole and will make your engine run rich. The copper wire doesn't remove anything but the gunk inside. Just a tip, before you learn the hard way like I did

 

[LABanker]

Thought I would update the post. Tks for the advice. After rechecking everything we could we tore apart the carb and sprayed in down with carb cleaner including each port, hole, jet etc... No better. Brought it back to my house and tore down carb again as I simply had decided it had to be a fueling problem. This time I also used a rubber tip on the end of my air compressor that allowed the tip to seal up the entry hole and went to town on it again. Bolted it back up and what do you know. Running like it did when he bought it years ago. Check another one for compressed air in the right hole. Put it all back together this weekend and this old 135 is back in service. Good to hear it running right after all those years. Brings back some memories. Tks again to all.

 

[Gale Hawkins]

Thanks for a detailed follow up. I wish all did this.