farm all m

becca1975 · May 11, 2015

Farmall M won't start. When it does runs like crap, it will pull itself along OK but when I shift to road gear the engine RPM slows down to about 700 rpm and it just putt putt putt putt. When its doing this it's unresponsive to the throttle change I have to shut it off and try to restart. I thought it was the governor not advancing the throttle. I removed the upper governor housing so I could see what was happening it appears that the throttle shaft is being advanced by the governor the way it should be. This is what I did to try to correct it carb overhaul, replaced points, cond. Cap, rotor, wires and plugs. Still barely runs, cyl compression ranges from 75-90 a little low I know, but still this thing went from running decent to like crap overnight. Great spark at coil but not so great at the plugs. interestingly though when I release the starter rod just as the engine stops turning a lot of times the engine will make a half revolution backwards but not violently. I need help please. Im not new to mechanical work 30+ years this has me stumped so any help would be appreciated.

Nick167 · May 11, 2015

I'd check to see if you have good gas flow out of the Carb also check the spark plug and point gap

Charlie M · May 11, 2015

I agree on the gas. I've had 3 tractors of the past couple of years not run due to crap in the fuel line or bottom of the tank.I'd also check the timing.See if you have any leaks in the manifold. I always check the free stuff first.

old · May 11, 2015

I would start by checking spark. You need a spark that is a nice blue/white and jump a 1/4 inch gap or more. If you have that move to gas flow. You need a good steady flow of gas out of the carb drain plug for at least 3 minutes. Catch the gas to check for dirt/water etc.

glennster · May 11, 2015

When you put the carb back on, did you get the linkage hooked up correctly from the governor???

GaryinKs · May 11, 2015

Check the condenser, sounds like weak ignition

Chance M · May 11, 2015

Compression is mighty low...if fire and fuel all checks out, might be time for an overhaul. Does it run better when it is cold?

becca1975 · May 11, 2015

I can't really say if it runs better if it
is cold it just started acting up. Thankd

Steve@Advance · May 11, 2015

Sounds like it could still have some sort of ignition problem. If it's battery ignition, have you checked the running primary voltage at the coil? Distributor bushings? Centrifugal advance and timing?

If it's magneto the coil may be leaking voltage to ground.

Does partially pulling the choke help? Make it worse?

Any smoke? Black rich smoke? White raw gas smell, ignition misfire?

Possible clogged exhaust or air cleaner?

jimg.allentown · May 12, 2015

With compression that low, and with the poor running and lack of power my first thought is that your timing chain might have jumped a tooth, BUT.....you need to address the poor spark issue before tearing into it. You can see if this is more or less likely with a vacuum gauge. You should have at least 21" of vacuum at idle. If vacuum is ok, I would look at the coil as a causing weak spark. Check the secondary resistance. I would expect it to be in the 5000 to 8000 ohm range.
Seems with 30+ years of mechanical experience, you would do some diagnosis before you start throwing parts at it.

Gary Mitchell · May 12, 2015

Sounding a lot like an intake manifold gasket leak. Mine acted a lot like that and a new intake manifold gasket fixed it.

David G · May 12, 2015

What timing chain?

I would suspect timing might be slow, check that.

jimg.allentown · May 12, 2015

Well, not being intimately familiar with that particular engine, I wasn't sure if it used gears or sprockets and chain. Symptoms still point to a valve timing problem. Even at 7 to 1 compression, readings should get up around 110psi. Also not sure what the compression ratio is in that engine. I DO know that anything under about 60 psi and the engine probably won't run well if at all.

Bryce · May 12, 2015

Ditto

farm all m

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