9n Has Trouble While Mowing

[Zaximus]

My 9n seems to be running fine while simply driving, including pulling weight. However, when I run the PTO to use my finish mower it gets bogged down and sometimes dies. When this is happening it starts to backfire every few minutes. I've also noticed that I have to pull the choke quite a bit when starting it up. I've looked around in the forums and it sounds like it could be a variety of things. I think I can rule out a wrong firing order since the spark plug wires run through a metal tube that runs each one to the appropriate plug and I haven't messed with that recently. Someone at the local tractor shop said it sounds like a fuel problem and I probably need to clean out the fuel tank and carb. Any suggestions on narrowing down the problem?

 

[HFJ]

fuel's certainly a possibility. pull the drain plug on the bottom of the carb and open the valve on the sediment bowl. u should fill a pint jar with gas in 2 or 3 minutes. if not, there are three screens between the tank and the drain plug on the carb. first is on top of the sediment bowl assembly, in the gas tank. next is insitde the sediment bowl assembly, at the top of the glass bowl. third is in the elbow where the fuel line enters the carb.

if you've got good flow, could be something plugging the carb itself, i'll leave that for the gurus.

 

[Ultradog MN]

Always, always check your spark First.
Verify that you have a bright bluish white
spark that will jump at least 1/4".
Short or yellowish spark will not do.
Requires no tools to pull a plug wire and
check.
Only then go on to fuel.

 

[Royse]

Check spark quality first.
If you do it after you let gas out, it could be a fire hazard.

If this problem is new and you haven't messed with the wires,
then you are probably right but the most common place to mix
the wires around is not at the plugs. Its at the distributor on
number 3 and 4. They are pretty easy to swap when new.

Have you checked/cleaned/gapped the points?
If spark quality is poor it may be as simple as that.

 

[Bruce (VA)]

Check out tip # 40.

Then answer this question:

When is the last time you replaced the
points, plugs, condenser, rotor & cap, set
the timing and cleaned the fuel screens?
75 Tips

 

[ASEguy]

Backfires through the intake or exhaust? I'm guessing exhaust. If it is try pulling the choke out a bit and see if it runs better. That doesn't guarantee fuel delivery as the reason but should eliminate the crossed wires. Basically your fuel mixture is getting into the exhaust stream without being ignited in the combustion chamber. I would definitely take a close look at the points.

 

[R Geiger]

You coludbe running three cylinders, they run pretty good on three under low power requirements.

 

[Zaximus]

It's backfiring in the exhaust. I haven't changed the spark plugs for a while, and I've never changed any of the other electrical components in the 3 years I've owned the tractor (except for the batter). Per everyone's advice I started with the spark. I went ahead and replaced the plugs with new ones (gapped at .025) and also cleaned some gunk out of the bottom of the air filter cup. I tried mowing and had a little more luck, but it may have been coincidental (maybe the grass was just drier). It still had some trouble by the end.

I finally checked it with an old spark plug set to 1/4". On each spark plug wire it seemed to produce a blue-purple spark that jumped the gap. It's a little hard to tell with that big of a gap since it wants to jump to the side sometimes, but as far as I can tell it's good.

I did some more mowing and I'm definitely noticing a pattern of it having more trouble the longer I run it. I mowed for 20 minutes before it really became challenging. I let it cool down for a few hours and came back and it worked better.

This may be unrelated and it may be my imagination, but it seems like it's hotter than usual (just based on the heat radiating off the engine). It has enough coolant, the radiator fan is running right (I just tightened the alternator belt), and it has enough oil. The impeller in the radiator also seems to be running. No steam or particular signs of running hot other than it just feeling hot to the touch (i.e. things other than the engine are hot just from proximity). I don't have a thermostat unfortunately. It's in the mid 90's here in Missouri and I've got 10w-30 oil in it.

Next time I run it I'll see if the choke has any effect on the problems.

 

[Elmo]

My dad always told me that most carburetor problems were in the ignition!
Elmo

 

[Bruce (VA)]

" I've never changed any of the other electrical components in the 3 years I've owned the tractor "

Do you think that might have something to do with your problem?

It's past time for you to replace the points, condenser, rotor & cap, set the timing and clean the fuel screens.

See tips 40, 66,67 & 68.
75 Tips

 

[Zaximus]

(quoted from post at 17:29:38 07/22/16) " I've never changed any of the other electrical components in the 3 years I've owned the tractor "

Do you think that might have something to do with your problem?

It's past time for you to replace the points, condenser, rotor & cap, set the timing and clean the fuel screens.

See tips 40, 66,67 & 68.
75 Tips

Tip 67 mentions annual maintenance for the points, but it doesn't mention how often things should be replaced. Are you just assuming mine need replaced due to lack of maintenance, or are you saying they should be routinely replaced less than 3 years apart?

Does anyone happen to know of any videos or walkthroughs for replacing these things, or would something like an I & T shop manual have those instructions? I'm not afraid of doing the work myself (I replaced the head gasket last year), but I don't have a background in engines so I need instructions.

Finally, looking online I'm seeing that I can buy a distributor with cap, points, and condenser all together for about $134. Is something like that a good bet, or should I for some reason buy the components individually? I'm also open to any general caveats about buying tractor parts since I don't know what to stay away from.

 

[Bruce (VA)]

" I'm also open to any general caveats about buying tractor parts since I don't know what to stay away from."

I?ve been working on old cars, trucks & tractors now for over 50 years. Whenever possible, I get OEM component parts rebuilt. Given the high probability that any new component part purchased for an N tractor is made somewhere overseas w/o adequate quality control, chances are very good that you will be disappointed. If you do not have a local rebuild shop, give these guys a call for a quote & shipping info:

Automotive Manufacturers Inc
2400 N Lombardy St Richmond, VA 23220
(804) 321-6861

They do mail order work. They rebuild carbs, clutches, pressure plates, water pumps, alternators, generators, starters & reline brakes.

Two recent examples come to mind. Some folks have been disappointed with the "new" water pumps they purchased because the housings are too thick & require longer studs. And I've seen new distributor plates made from pot metal; the screws are harder than the plate. About the 3rd time you change the points, the screw holes will wallow out.

These guys should be able to help you w/ used parts:

John Smith smith8NATatt.net

Rod Mondor fltractorATpeoplepc.com

Replace the AT in the address w/ @

Rod forest lake tractor 651 464 4628

For new parts, use this site, nnalert's or Dennis Carpenter. Locally, NAPA & O'Rielly parts are usually ok if you have a part number.

"
Finally, looking online I'm seeing that I can buy a distributor with cap, points, and condenser all together for about $134. Is something like that a good bet, or should I for some reason buy the components individually? "

I'd say it would make a good bookend.

" Are you just assuming mine need replaced due to lack of maintenance, or are you saying they should be routinely replaced less than 3 years apart?"

Given the performance problems you described, and the fact that you have not touched the points in 3 years, you need to at least check the gap & lube them. But, if you're going to pull the distributor after 3 years of inattention, you might just as well replace all of the components w/ quality parts. And check the bushings. Next year, assuming good bushings & proper installation of the points, all that will be needed is lubing the cam & opening the points a bit.

" Does anyone happen to know of any videos or walkthroughs for replacing these things, or would something like an I & T shop manual have those instructions? "

Get the 3 manuals mentioned in tip # 39. Then, before you start a repair, ask for comments/suggestions/advice here.
75 Tips

 

[Elmo]

(quoted from post at 17:58:54 07/24/16) " I'm also open to any general caveats about buying tractor parts since I don't know what to stay away from."

I?ve been working on old cars, trucks & tractors now for over 50 years. Whenever possible, I get OEM component parts rebuilt. Given the high probability that any new component part purchased for an N tractor is made somewhere overseas w/o adequate quality control, chances are very good that you will be disappointed. If you do not have a local rebuild shop, give these guys a call for a quote & shipping info:

Automotive Manufacturers Inc
2400 N Lombardy St Richmond, VA 23220
(804) 321-6861

They do mail order work. They rebuild carbs, clutches, pressure plates, water pumps, alternators, generators, starters & reline brakes.

Two recent examples come to mind. Some folks have been disappointed with the "new" water pumps they purchased because the housings are too thick & require longer studs. And I've seen new distributor plates made from pot metal; the screws are harder than the plate. About the 3rd time you change the points, the screw holes will wallow out.

These guys should be able to help you w/ used parts:

John Smith smith8NATatt.net

Rod Mondor fltractorATpeoplepc.com

Replace the AT in the address w/ @

Rod forest lake tractor 651 464 4628

For new parts, use this site, nnalert's or Dennis Carpenter. Locally, NAPA & O'Rielly parts are usually ok if you have a part number.

"
Finally, looking online I'm seeing that I can buy a distributor with cap, points, and condenser all together for about $134. Is something like that a good bet, or should I for some reason buy the components individually? "

I'd say it would make a good bookend.

" Are you just assuming mine need replaced due to lack of maintenance, or are you saying they should be routinely replaced less than 3 years apart?"

Given the performance problems you described, and the fact that you have not touched the points in 3 years, you need to at least check the gap & lube them. But, if you're going to pull the distributor after 3 years of inattention, you might just as well replace all of the components w/ quality parts. And check the bushings. Next year, assuming good bushings & proper installation of the points, all that will be needed is lubing the cam & opening the points a bit.

" Does anyone happen to know of any videos or walkthroughs for replacing these things, or would something like an I & T shop manual have those instructions? "

Get the 3 manuals mentioned in tip # 39. Then, before you start a repair, ask for comments/suggestions/advice here.
75 Tips

Good advise!
Elmo