My 861 started cutting out and stalling. any ideas?

[donthaveacoolnickname]

I think it's a 1955.
Converted to 12v with an alt.
New Plugs. Oil bath and air filer assembly good
Sediment bowl clean. Carb flows fuel from plug (seems ok, but don't know what good is)
Forgot to check points but cap and rotor looked good.
I tapped on the card with a deadblow while it was running and also while draining in case there was something stuck in the needle seat or float area, no change.

It starts easily. Will idle great all day. I can rev it up and it doesn't seem to die.

Problem: I let it warm up. I go to mow field and I only get a few hundred yards in taller weeds and grass and then it starts to buck a lot and revs drop. It'll buck and recover a bit but I can't continue mowing. If I stop it may recover a bit but if I let it continue it'll die. So, I sit for a few seconds and it'll fire right back up and I can mow a little ways until it starts again. I can even rev it up while sitting and it'll hold the revs. I've used it to move gravel and dirt around with the blade a few weeks ago and had no problems.

It seems like maybe a fuel problem but how and where as flow looked ok but no idea how to measure. Or, coil getting bad when warm?

Also just curious if I do ever need a coil does it need internal resistor?

Any thoughts are appreciated, thanks.

-Sean

 

[Unclewillie]

I think it's a 1955.
Converted to 12v with an alt.
New Plugs. Oil bath and air filer assembly good
Sediment bowl clean. Carb flows fuel from plug (seems ok, but don't know what good is)
Forgot to check points but cap and rotor looked good.
I tapped on the card with a deadblow while it was running and also while draining in case there was something stuck in the needle seat or float area, no change.

It starts easily. Will idle great all day. I can rev it up and it doesn't seem to die.

Problem: I let it warm up. I go to mow field and I only get a few hundred yards in taller weeds and grass and then it starts to buck a lot and revs drop. It'll buck and recover a bit but I can't continue mowing. If I stop it may recover a bit but if I let it continue it'll die. So, I sit for a few seconds and it'll fire right back up and I can mow a little ways until it starts again. I can even rev it up while sitting and it'll hold the revs. I've used it to move gravel and dirt around with the blade a few weeks ago and had no problems.

It seems like maybe a fuel problem but how and where as flow looked ok but no idea how to measure. Or, coil getting bad when warm?

Also just curious if I do ever need a coil does it need internal resistor?

Any thoughts are appreciated, thanks.

-Sean

if the fuel is good I would suspect a issue with the governor, governor adjustment or weak governor springs.

 

[John0829]

Check for a bad coil.

 

[donthaveacoolnickname]

Here's an update. I can drive around the field at pto speed in 2nd or 3rd gear all day long. If I start to mow within a couple hundred yards it'll start the bucking and die out if I don't push clutch and throttle back. If I sit for a bit at idle I can mow maybe another few hundred feet before it does it again. ALSO, it'll do it if I head up hill after about 100 feet, but not on level ground. Both of those put more load on the engine but neither start the problem immediately.

So, fuel starvation? I'll check the coil tomorrow and I'm learning how to assess the governor, thanks.

 

[inpo44]

Those 800 series Fords were known for having vapor lock problems (fuel boiling in the fuel line). Gas line reroutes with horizontal runs and missing heat shields are some of the causes. Ethanol in gasoline has also been a contributor. A totally full gas tank would minimize it (by increasing the pressure in the fuel line)and be a easy test.

 

[wolc123]

I had similar issues with an old Allis Chalmers C. It turned out to be rust and crud build up in the bottom of the gas tank. I ended up removing the tank, added some nails, nuts, bolts, and kerosene. Then I shook it up, dumped everything out, put it back on, and the problem was solved.

 

[nyone]

Your not getting enough fuel flow to keep the bowl full. They have a screen at the pickup in the tank. You should beable to see it through the tank fill.

Does yours still have the glass fuel bowl? Is is nearly empty or have alot of air or low flow when the problem happens?