9N I need the experts! Help!

Anonymous-0

Well-known Member
Ok guys, I need some diagnosis. Have a 9N that I've had for years. Always ran great. Now with my new sickle mower installed it keeps dying. Pulled the governor.Looks great, no flat spots on balls. Changed cthe points, rotor and condenser.Had the carb apart TWICE. This is a rebuilt engine. Maybe 100 hours on it. Starts right up, and when cold will run for about 10 minutes . Can rev the throttle, no problem. After its hot will run only a couple of minutes under load. Stalls out but will start right up. Used to bush hog with this tractor, so its used to having a load on it. Checked the sediment bowl, fuel line, and i know about the hidden vent in the tank under the hood. Going to try another carb, and another coil. Any thoughts guys? I used this setup with the mower for an afternoon and it ran fine. Just went all of a sudden. Help!!!!
 
It is important for you to tell us if your tractor has a 6 volt or 12 volt electrical system. The troubleshooting is different based upon the configuration of your engine.

It takes three things for an engine to run: spark at the right time, compression, & fuel in the right mixture. For the moment, forget about compression & concentrate on narrowing the problem down to spark or fuel.

There are three very important tools you always need to have in your N tool box: a 3 inch piece of wire w/ alligator clips on each end, an old spark plug w/ the gap opened to at least 3/16” ( ¼” is better) and a 7/16 box end wrench. (see tip # 50 at the link below) And, you really do need a working ammeter on the tractor; it is a very important diagnostic tool. With these tools, you can quickly narrow down most N problems to spark or fuel.

Next time it stops, check quickly for fuel then spark. When I say quickly, I mean get off the seat, grab the tools & do it right then. Do not wait a minute or two. First, check for fuel. Get a can & put it under the carb. Remove the bolt in the bottom of the carb; as long as the fuel is turned on, you should see gas flowing out of the carb. Let it run for at least 30 seconds. If it’s a dribble, or runs for 5 seconds & stops, or none at all, you have solved half the problem: it’s fuel related. If gas flows well out of the carb & only stops when you turn it off at the sediment bowl, chances are very good it’s not a fuel problem. So, next, turn the key on, crank the engine & look at the ammeter. What is the needle doing? Does it show a constant discharge, no movement at all, or does it move back & forth slightly? Next, get the old plug, ground it to a rust & paint free spot on the engine, turn the key on & crank the engine. If the spark jumps the 3/16” gap, you probably don’t have a spark problem. If it won’t jump the 3/16” gap, you have a spark problem. If the ammeter needle shows a constant discharge, or doesn’t move at all, that also tells you that you have a spark problem. Jump the ignition switch w/ your jumper wire & see what happens. If it runs, you found the problem. If it doesn’t have spark after you jump the ignition switch, post back for more info on further troubleshooting. (and do not forget to turn the ignition switch off; see tip # 38)

If it does not have gas coming out of the carb at a steady stream w/ the bolt out for at least 30 seconds, you have a fuel problem. First, remove the gas cap. Your vent could be clogged & it vacuum locked. If that doesn’t work, tap the carb bowl w/ a hammer handle in case the float is sticking closed. (don’t whack it w/ the head of the hammer; you can crack the bowl). If you still don’t see gas flowing, the N has three fuel screens; one in the brass elbow, one in the top of the sediment bowl & one on the stem of the sediment bowl in the gas tank. Check the screen in the elbow & the screen in the top of the sediment bowl. (don’t worry about the one in the tank) Both probably need to be cleaned. If you have the fuel knob turned on all the way, & 1 gallon or less in the tank, it may be trying to feed off of the reserve inlet which is probably clogged. Only open it 2 full turns. Put at least 2 gallons in the tank. (and do not forget to turn the gas off; see tip # 9)


There are ways to check for spark & fuel that work & ways that don't. For example, having gas to the carb is nice, but having it past the float is what counts! That’s why removing the 7/16” bolt in the bottom of the carb is the way to check for fuel. And, same thing w/ spark at the plugs. Some folks think that checking for spark means pulling a plug wire off & looking for one. Well, it's the distance the spark jumps at the plug that gives you the info you want. It takes about 17kv to jump a 3/16" gap & 22kv to jump ¼” in the open air. Remember, it’s 14psi outside of the engine & about 90psi at a 6:1 compression ratio in the cylinders & compressed air creates electrical resistance, so you really need the 17-22kv to fire the plugs when the engine is running. A store bought plug checker will work better than an old plug because it won’t shock the snot out of you like an old plug might!
75 Tips
 
Check your spark when it dies. Needs to be a blue white in color and jump a 1/4 inch gap or more. Maybe a simple ignition switch or a simple bad new condenser. If you have a good spark check for fuel flow out the carb drain plus. Trouble shoot always before doing parts or you may add to the problem
 
shorting a switch is the same as jumping it.

IE.. short ircuit the input and output.

same thing the switch is doing when on..e tc.
 
Thanks for your advice Bruce. My N is a 12 volt. Like I said it always ran great.I have a feeling its the screen at the top of the sediment bowl. Haven,t checked it yet. Was going to but have to drain a full tank of gas(of course) I always like your posts on here and I think I've seen your work in the N- News? Be a few days till I get to it. Rain finally stopped... Time to get some hay in the barn. With the other tractors!
 
My meter seems to be working. Shows discharge when i turn the key, then goes to charge when the alternator self-excites. Its always done this, so I don't think its the meter. thanks for the input
 
I know what you mean by adding new parts too quickly. Learned that by messing with cars all these years. You're right, its usually something simple. This one has me scratching my head though. thanks for the advice
 
Yes I had thought of that too. Just bypassing the switch. I have learned alot from all you guys just by reading all your posts all the time. Gives me more to think about...as I toss and turn all night trying to sleep! Could be this, could be that!Next month I'll be trying to figure out my I/H Suyper M. I'm a glutton for punishment. Hi I'm Darryl and I have a rust problem! Can't get enough.... Thanks to all who rersponded. I'll post again when I get it sorted out.
 

If you had a voltmeter their would be no question if the ignition switch were good are bad... Their would be no need to short/jump are guess... Nutter reason to ditch a useless ampmeter...
 
Maybe like a IH 340 I have been working on. Had it running good the other day then all at once it started to miss and then died. Check spark and fuel and both seemed ok. Then yesterday i looked at it again and found that the rotor was not turning. Pulled the distributor and found a few teeth on the distributor drive gear had gone AWOL on it. The od thing was it would some times back fire then the next time try to start so was hard to figure out till I saw the rotor not turning so knew where to start looking.
 
" I have a feeling its the screen at the top of the sediment bowl. Haven,t checked it yet. Was going to but have to drain a full tank of gas"

No you don't.

Just turn the gas off & remove the bowl.

Get a new gasket & screen.

Put the screen in first, then the gasket.

You can test the screen in the tank after you take the bowl off. Put a can up there to catch the gas & then turn the gas on.
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75 Tips
 

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