8n quits running.

[9nericm]

My uncles 8n will run for about 30
minutes then start sputtering and
eventually quit. I put new points in last
summer and it had run like a top until
starting this a cpl weeks ago. A couple
days ago I put a new condenser, plugs &
plug wires after he told me what it was
doing but it didnt help. I'm thinking
possibly resistor, coil or maybe the
generator not charging or bad battery but
he also said that his sediment bowl
screws out by itself as he mows so might
be something there. If anyone on here has
ever had a similar problem? It's a amazon
sediment bowl that I put on when I
installed points.

Tractor Info:
Either a 49 or 50 8n, completely restored
about 5 years ago by someone who has
redone several. Front mount distributor.
6 volt setup Never had any issues yet
other than me putting points in for him.

Thanks for any help y'all have helped me
get my 9n running excellently!

 

[HFJ]

don't guess whether it's spark or fuel, it's easy to tell which. if you don't own an adjustable gap spark tester, spend the 8 bucks and get one. the moment it dies, take that tester, set to a quarter inch gap, and make sure the spark will jump it.

if it does, then pull the plug out of the bottom of the carb, open the valve on the sediment bowl, and time how long it takes to fill a pint jar with gas. should be 2 minutes or less.

what does he mean the sediment bowl unscrews itself? how is that possible? what does the fuel line do while this is happening?

 

[Eman85]

Do the spark and fuel flow test. No matter what you need to address the fuel sediment bowl unscrews issue and or buy a fire extinguisher. If it was truly restored, it should have the correct fuel shutoff with screens and steel fuel line.
Since you say it runs put a voltmeter on it and check the charging system output.

 

[9nericm]

That makes perfect sense to test the
spark first, I have a spark tester so ill
check it asap. Sometimes it just helps
to get someone to remind me something I
should know to do. Probably a lot to do
with getting older everyday. Thanks for
the info!

The sediment bowl screw that you turn
open 2 turns keeps opening up as he mows.
Which to me would only give it more fuel
to work with but I wasn't sure if maybe
they get vacuum locked when this happens.

Thanks again

 

[9nericm]

Will do thank you for the advice!

Eric

 

[HFJ]

you're correct. the valve unscrewing itself would cause more gas to be available if anything, not less. it wouldn't cause a vacuum lock. but the tank vent can become plugged. if the fuel flow fails the pint in 2 minutes test, try it again with the gas cap loosened. if that fixes it, take the cap off and drill a tiny hole in it, or get a vented cap.

i've noticed that my memory doesn't seem to be improving with age either. it's the darndest thing.

 

[Jim L WA]

9nericm, as for the fuel shutoff backing out, just tighten the nut that the valve stem comes out from.

 

[R Geiger]

If it unscrews to the full open position, it would be puling fuel from the bottom of the 4tank and that port may be plugged. open it all the way and do the fuel flow est. one pint from bottom of carb in 2 to 3 minutes.

 

[Jim L WA]

(quoted from post at 15:02:20 06/10/23) If it unscrews to the full open position, it would be puling fuel from the bottom of the 4tank and that port may be plugged. open it all the way and do the fuel flow est. one pint from bottom of carb in 2 to 3 minutes.

If the tank had plenty of gas in it wouldn't it still come down the tube above the screen?

 

[R Geiger]

Not sure how ir is made, is it either or either and?

 

[deanostoybox]

It is main, or main and reserve.

 

[Mad Farmer]

(quoted from post at 17:36:41 06/09/23) My uncles 8n will run for about 30
minutes then start sputtering and
eventually quit. I put new points in last
summer and it had run like a top until
starting this a cpl weeks ago. A couple
days ago I put a new condenser, plugs &
plug wires after he told me what it was
doing but it didnt help. I'm thinking
possibly resistor, coil or maybe the
generator not charging or bad battery but
he also said that his sediment bowl
screws out by itself as he mows so might
be something there. If anyone on here has
ever had a similar problem? It's a amazon
sediment bowl that I put on when I
installed points.

Tractor Info:
Either a 49 or 50 8n, completely restored
about 5 years ago by someone who has
redone several. Front mount distributor.
6 volt setup Never had any issues yet
other than me putting points in for him.

Thanks for any help y'all have helped me
get my 9n running excellently!

Mine starting doing that hot weather/summer, turned out to be the coil.

Check spark as soon as it dies. If you let it cool down coil might start working again. Mine had run all winter fine and started dying when using rotary cutter summertime.

 

[9nericm]

I apologize for the delay in getting back with everyone & thanking them. It end up being the distributor cam & weights were wore out & the points needed cleaned & adjusted. He ordered a new coil while waiting on me so the tractor has a fresh tune up now as well! Runs great now but blew a intake/exhaust manifold gasket by #4 cylinder when mowing after getting it running good again so I had a quick question on that.

Will a blown manifold/intake gasket create vacuum loss & cause the governor to not work properly?

Reason I ask is now when he starts mowing up a slight grade it bogs the tractor down more than before. With my 9n, whenever I start bush hogging up a grade or thru heavy thick stuff my tractors governor will kick in adding more fuel immediately when it senses more strain on the engine so I'm thinking the manifold pressure leaking is what's causing his to not add more fuel when needed.

Thanks again for all the help.

 

[HFJ]

i have no idea about the governor issue, but the manifold gasket needs to be fixed, regardless of the governor's behavior. if not, it can lead to erosion of the manifold and block. i'd say fix that and if the other issue goes away, you're done

 

[Dave G9N]

(quoted from post at 09:52:22 07/12/23) I apologize for the delay in getting back with everyone & thanking them. It end up being the distributor cam & weights were wore out & the points needed cleaned & adjusted. He ordered a new coil while waiting on me so the tractor has a fresh tune up now as well! Runs great now but blew a intake/exhaust manifold gasket by #4 cylinder when mowing after getting it running good again so I had a quick question on that.

Will a blown manifold/intake gasket create vacuum loss & cause the governor to not work properly?

Reason I ask is now when he starts mowing up a slight grade it bogs the tractor down more than before. With my 9n, whenever I start bush hogging up a grade or thru heavy thick stuff my tractors governor will kick in adding more fuel immediately when it senses more strain on the engine so I'm thinking the manifold pressure leaking is what's causing his to not add more fuel when needed.

Thanks again for all the help.

t sounds like the governor is working properly and there is a manifold leak making it work a lot harder. The governor is strictly mechanical. It responds to the throttle setting and engine speed only. It can open and close the throttle, but if the mixture is off, there isn't anything the governor can do about that.

A vacuum leak in the intake manifold would cause the acceleration problem. The governor will open the throttle as the engine starts to slow, but it is the vacuum leak screwing up the mixture that causes the initial loss of power. As it slows more, the governor gives it more throttle, so you get a lot of throttle movement for a small change in load.

 

[9nericm]

Thanks for the info, received the gaskets earlier in the week so I plan on replacing the intake/exhaust manifold gaskets this weekend. I went ahead & ordered lifter tappet cover gaskets as well & I'm going to run the valves while I have everything out of the way. Appreciate all the info!