MF 135 stops after 30 Min.

[RKeithByrd]

My MF 135 gas tractor will run about 30 min or so then dies but after an hour or so it will start and run fine for about another 30 min. Any ideas appreciated. Thanks. Robert

 

[pmsmechanic]

Run the tractor until it stops. Remove the fuel line and see what kind of flow you have. I'm thinking that the fuel flow is restricted in some way. Just guessing as you didn;t say how the motor stopped. Does it just die or does it change sound while running and then sputter and quit?

If it's not the fuel then move onto the spark. After the motor stops pull the center wire out of the distributer cap. Hold it within a quarter inch of metal on the tractor and crank the motor. Make sure the tractor is in neutral before you do this. There should be a good healthy spark. If not then check the points and the coil.

 

[RKeithByrd]

It is a 1969 4 cyl gas and when it stops it is like the key was turned off. I will try the things you listed above and let you know what happens. Thanks.

 

[48volt]

on the diesel there is a small filter in the top on the fuel tap in the fuel tank , maybe the same on gas tank?
this filter does clog up.

 

[pmsmechanic]

It is a 1969 4 cyl gas and when it stops it is like the key was turned off. I will try the things you listed above and let you know what happens. Thanks.

Ok so it could be that as the coil gets warm the resistance inside increases until there is no more spark. Most likely though is that the points are barely opening and as the engine warms up they don't open at all or develop enough resistance that they don't let any current through.

 

[pmsmechanic]

on the diesel there is a small filter in the top on the fuel tap in the fuel tank , maybe the same on gas tank?
this filter does clog up.

If this is the case then blowing backward through the line will temporarily cure the problem till all the junk settles around the intake screen again. Best cure is to pull the screen out and clean it. Make sure you catch the gas that runs out but also make sure you filter it good before you put it back in the tank. Or just give the gas to someone you don't like.

 

[flusher]

Ok so it could be that as the coil gets warm the resistance inside increases until there is no more spark. Most likely though is that the points are barely opening and as the engine warms up they don't open at all or develop enough resistance that they don't let any current through.

If it's points, the distributor cam could be worn.

 

[phiferpharm]

I had the same problem with a FarmTrac I used to own. It was a small screen filter located at the bottom of the fuel tank getting clogged up with what looked like algae. I emptied out the tank, cleaned up the junk and put a see-through inline filter on.

After that only solved the problem for a short period of time, I replaced the filter in the FarmTrac with my present Kioti DK45. It solved the problem....

 

[bruceatlam]

This could be an indicator of another classic problem with gas tractors. The fuel tank cap is vented --- has a small hole in it to let air in as you use fuel. If air can't enter through that hole, the tank will develop a vacuum as you use fuel and fuel flow will stop as a result. Check to make sure that vent hole in the fuel cap is clear. Your symptoms are classic for this problem ---- takes about 1/2 hour for the vacuum to develop and then, since the fuel cap seal isn't perfect, after and hour or sitting the vacuum relaxes and fuel flow again for another short while.

 

[RKeithByrd]

Thanks everyone for helping out. We have had two days of rain here and now mud so I will get back to you all when I get a chance to try your suggestions. Robert

 

[bigdeano]

There's a good chance it's the ignition condenser. Sometimes they short out when they get hot, then will work again when they cool off for a while. I've had a couple of them do it.

 

[RKeithByrd]

Ok here is what I have done so far. Oh by the way this is a 3 cyl gas Perkins engine.

1. I have cleaned out the glass bowl on fuel system and change the fuel filter.
2. Changed the coil
3. Changed the condenser
4. Checked the points and they seem to be working correctly
5. Hot wired the tractor to check and see if the switch was some how malfunctioning even though it isn't GM. (couldn't pass on that one, sorry)
6. Changed the fuel tank cap

I have not yet checked for a screen in the fuel tank, but I do have a good fuel flow after the tractor stops. The Perkins pulls hard with governors opening correctly and runs smooth until it stops. It might sputter just a very little bit but for the most part it just stops like the key was turned off. Even when I had it hot wired but when it started running again in about an hour or so I couldn't get it to stop until I remembered that I had hot wired it so the switch was by passed when it stopped.

Thanks for all the help got me stumped.

Robert

 

[bigdeano]

I once had a wire short to the distributor case where it went thru to hook to the points. Next time it quits hook a voltmeter to the coil terminal that goes to the distributor and crank the engine with the starter. If the voltage goes up and down you'll know the points are working correctly. Don't know what else to suggest.

 

[jimmysisson]

Have you verified good fat blue spark when you first try to restart? Quitting abruptly doesn't sound like fuel. Confirm spark, or as said condenser, coil, or wires to either.
Also have you tried moving the distributor shaft, with rotor removed? Too much play there can mess up points settings and timing. Tried replacing the cap and rotor?
Keep plugging, you'll get it.
Jim

 

[hd5]

Did you get this figured out? My dad's 71 3 cylinder is doing the exact same thing. He has been focused on the carb. I'm going to have him try some of the other suggestions. But if you found the solution, please let me know. Before he talks me into taking off work to help him....