I have 1941 9N which I have owned for about 30 years. This is a working tractor and its primary purpose is plowing snow. Parts have been replaced over the years as required and the tractor generally runs well. Over the last few months I have noticed after I work the tractor for a half hour plowing the tractor starts to surge to the point of wanting to stall. If it shuts down and u start it after 15 minutes it then runs fine. My question: could this be the coil. It seems to be related to heat as it only happens after working the tractor for a bit. Any ideas would be appreciated. I have replaced the coil a few times over the years but have not experienced this type symptom
- Thread starter Bur419N
- Start date
It could be the coil, but could also be the condenser. The condenser is cheaper, but now days it's possible to get a bad one out of the box. Do you have any old ones you've kept over the years?
One way or another, replace the condenser first before spending more on a coil that may not be bad.
One way or another, replace the condenser first before spending more on a coil that may not be bad.
Bruce (VA)
Well-known Member
I'll narrow it down, it's most likely spark or fuel.
I go for the fast fun easy and cheap tests first. Opening the fuel cap when it does it will tell you if the vent is plugged, might take a minute for it to stop surging. I'd also do a fuel flow test as it might have a partially clogged screen. Ignition switches do fail you can try wiggling the key and the wires on the back, wires come loose also.
I go for the fast fun easy and cheap tests first. Opening the fuel cap when it does it will tell you if the vent is plugged, might take a minute for it to stop surging. I'd also do a fuel flow test as it might have a partially clogged screen. Ignition switches do fail you can try wiggling the key and the wires on the back, wires come loose also.
So if you didn't work the tractor it wouldn't do it? I would start by pulling the plug on the carb and make sure I could fill a quart jar
in a reasonable time. If that's good, I would go after spark, starting with points. Surging is typically related to a lean condition in my
experience with some engines.
in a reasonable time. If that's good, I would go after spark, starting with points. Surging is typically related to a lean condition in my
experience with some engines.
Tim PloughNman Daley RIP
Well-known Member
Yeah, I'd say it is a fuel issue. How does he figure it is an electrical/coil issue? That should be the carb drain plug or fuel line to carb should put out 1-PINT in 2 minutes with no hesitation or sputtering. Always do the Fuel Flow Test first and if it passes, leave it alone and move on to electrical. If it fails, troubleshoot all possible causes for fuel obstruction, rebuilding the carb a last resort.
Tim Daley(MI)
Tim Daley(MI)
Thanks for all the good ideas. Update. Went out today and
tractor started up and ran for 10 minutes. Loosened the gas
cap when it started to surge. No difference. Seemed to run
better when I pulled the choke half way but eventually quit.
I changed the fuel filter in case it was plugged. Got it going
again after a bit but it is sick. Havent had a chance to
change the condenser but it seems to be getting sicker.
Thinking it may be a fuel or carb issue. Will pull the bowl off
the petcock and check the screen. Not sure why it takes a
bit of time to show up
tractor started up and ran for 10 minutes. Loosened the gas
cap when it started to surge. No difference. Seemed to run
better when I pulled the choke half way but eventually quit.
I changed the fuel filter in case it was plugged. Got it going
again after a bit but it is sick. Havent had a chance to
change the condenser but it seems to be getting sicker.
Thinking it may be a fuel or carb issue. Will pull the bowl off
the petcock and check the screen. Not sure why it takes a
bit of time to show up
It's about fuel demand. The harder he works the tractor, the greater the fuel demand. If the demand is restricted, you can get a lean surge, and if
the surge gets more exaggerated while it's being worked, he is probably getting leaner as it starts to lower the float bowl level to the
point of dying. Gravity then refills the bowl and it can start back up. I'm not suggesting it has to be fuel, but a simple check of fuel flow
can tell a lot.
the surge gets more exaggerated while it's being worked, he is probably getting leaner as it starts to lower the float bowl level to the
point of dying. Gravity then refills the bowl and it can start back up. I'm not suggesting it has to be fuel, but a simple check of fuel flow
can tell a lot.
Did you remove the whole fuel shutoff assy. from the tank, there's a screen in the tank. Also 2 fuel pickups in there, one is for reserve. Did you remove the glass fuel bowl and remove and clean the screen above it? Do you have an aftermarket inline fuel filter in the steel line from the shutoff to the carburetor? Is that what you replaced?
To do the fuel flow test did you remove the plug at the bottom of the float bowl and then turn the fuel on and see how long it takes to fill a pint jar?
To do the fuel flow test did you remove the plug at the bottom of the float bowl and then turn the fuel on and see how long it takes to fill a pint jar?
No I did it from the inlet line into the carb. Seemed good. Also from the petcock with bowl removed. In line filter is in the steel line from petcock to carb. I could remove the petcock from the tank but I replaced it a few years ago and it seemed fine. I also took the carb apart a few months ago and cleaned it. Thanks very much for your help. I am going to see if it continues and then go back to the drawing board
Mad Farmer
Well-known Member
- Location
- Northeast
Inline filters installed in the steel line can be problematic. Most are designed to be used with pressurized systems having a fuel pump. The ones for gravity feed systems are hard to find. Ns were not designed for inline filters.
Did you check the steel line, below the inline filter? Check flow at bowl drain then work back to the tank. Don't forget carb inlet elbow screen and possibility of a float sticking.
Sometimes a few wacks on the float bowl will free a sticky float.
Again I am so happy to hear all the comments and ideas. Things have now changed for the worse. Now runs for 5 minutes and starts to surge. Seems to idle ok but once I try to move it will stall. Thought I had things cleaned up as it ran for 20 minutes the other day. Going to change the condenser tomorrow and if that doesnt work I think I will change the coil. Have to do something to chase this problem
u really should perform the fuel flow test again, thru the plug in the bottom of the carb bowl. by removing the line at the inlet, u have not proven proper function of the float. when the tractor starts to surge, shut it off and perform the flow test right away.
assuming it passes that test, and before i replaced anything electrical, i would jumper past the ignition switch as bruce suggested.
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