9N/8N weak spark

Hamige

New User
I have a 6v, 9N tractor that has a front mounted distributor 8N engine. I rebuilt the engine several years ago but have been having trouble starting it recently. Engine turns over at the normal speed but doesn't want to start. When I jump start using a 12v battery, the tractor starts right up. Figured that I had a weak spark caused by a weak battery. Old battery was putting out 6.33 volts. I replace the battery. Tractor started on its own power a few time but I'm back to having to jump it again. Could the starter be getting tired and needing rebuild/replaced? Also, how many amps should my generator be putting out. Any advice would help.
 


" Also, how many amps should my generator be putting out"

Depends on the generator. What is it?

Regardless, it needs to put out 7.5 volts. Amps depends on the load & model of generator.

" Could the starter be getting tired and needing rebuild/replaced?"

Yea, but that would be down on the list of possibilities; I'd check the simple stuff first.

Make sure that new battery is fully charged. As in put it on a battery charger. (see tip # 60)

" I rebuilt the engine several years ago.."
That's nice, but when did you last replace the points, plugs, condenser, rotor & cap & set the timing?
75 Tips
 
I'm not sure what model generator I have. It has an adjusting screw for High & Low and an oil port for the bearing. I've change points several times including recently when I started having problems. Plugs too. I'll put the new battery on a slow charge and make sure it id fully charged.
 
Hamige.......interesting name......8N engine has 6.5:1 compression vs 9N's 6.0 compression fer about 3-hp difference. As fer the 6-volt battery, 6.33-volts is NORMAL. Yer front mount genny is an 11-amp genny. When Ford went to the 5-nipple sidemount with genny on the left side, it changed to a 20-amp genny. You can count nipples, can't you?

2-things happen when you boost with 12-volts. It spins faster fer more dynamic compression; and 2nd 12-volts make hotter sparkies.

uh?.....when was the last time you replaced yer points? (0.015") They have a BIG effect on yer sparkies. You do know ittza 15-min job to replace yer points, don't you? Just unsnapple yer capple and remove the 2-bolts and walk to the kitchen table. Adjust the points fer 0.015" gap. Remember to "polish" the invisible corrosion from between the points. I clamp a corner of a $1-bill between the points and pull. Iff'n yer really cheap, tear a strip from HEAVY brown paper grocery sack and use that. Then finger start yer 2-bolts and install the rotor. Rotate the rotors OFF-SET drive tang with rotor until the OFF-SET tang fits the OFF-SET camshaft slot. Now tighten yer 2-bolts and re-snapple yer capple and top mounted wire. Simple, eh?

Is yer starter motor tired? I doubt it. .......HTH, the amazed Dell
 
Replacing points, condenser, setting gap to .015, cleaning contacts on distributor cap was one of the first things I did. I'm on this forum because nothing I've done has helped.
 
Hamige.......thats an 11-amp genny and YOU are the voltage regulator. That is what the screw is for. With throttle lever about 1/3 range, adjust the screw fer about 3-5 amps charge. Generally haffta re-adjust iff'n you have headlites ON-OFF.

About yer battery. You can have a DEAD cell and still read about 6.33-volts ...but... it won't have enuff stuff (AMPS) to turn yer starter motor ........electrical Dell
 
We also need to know a little more on your generator and voltage regulator or round can cut-out. Does your generator have one wire or three? If it is a one-wire unit, then you should have the round-can cutout circuit. Is it wired correctly? If the generator has three wires, then it should have a square can voltage regulator. Is it wired correctly? Is the starter the 9N style with one wire and no solenoid? You say it has an 8N block, then it should have an 8N starter with a solenoid, but I would not pull that just yet. Wiring good and correct? Ballast resistor in place and wired correctly? If everything electrical passes the tests, then it may be a fuel issue. Three things are needed -fuel, spark, and compression. Start with basics before thinking to just throw all kinds of new parts/money into the mix. You can always take your starter, generator, voltage regulator, coil, ammeter, and battery to your local reputable starter/alternator guy and he can bench test all of them usually for free.

[i:654c4848f0][b:654c4848f0]<font size="4">Tim Daley(MI)</font>[/b:654c4848f0][/i:654c4848f0]<table width="100" border="1" cellpadding="0" cellspacing="0" bordercolor="#000000"><tr><td height="25" colspan="2" bgcolor="#CC0000">
<font color="#FFFFFF" size="3">*9N653I* & *8NI55I3*</font>​
</td></tr><tr><td>
TPD9N100.jpg
</td><td>
TPD8N100.jpg
</td></tr></table>
 
You said that the battery puts out 6.33 V. What is the battery voltage at the battery when the tractor is running and your throttle lever is about midway.
If the Jenny is working the voltage should be higher.
 
I have a one wire generator and a one wire starter. I rebuilt the engine about 8 years ago. Tractor started first time after reassembly and ran great for the last 7 years with the occasional points, plugs, cap replacement. Another symptom was after brush hogging the the field and the tractor was hot, it would miss out and die if I dropped the idle too low. Tractor wouldn't start until sitting for several hours or over night.
 
" Another symptom was after brush hogging the the field and the tractor was hot, it would miss out and die if I dropped the idle too low. Tractor wouldn't start until sitting for several hours or over night."

Ahhh, some more important information.

That info, along with " Engine turns over at the normal speed but doesn't want to start. When I jump start using a 12v battery, the tractor starts right up. " tells me that you have a weak battery or a failing front coil. (does it have a front coil?)

" I'll put the new battery on a slow charge and make sure it id fully charged. "

You can fully charge a battery w/ a dead cell all day & it won't hold the charge. Check the battery w/ a hydrometer. Or better yet, have it load tested. You won't be the first guy to have a new battery go bad.

Once you confirm the condition of the battery, check the spark as soon as it stops running while the tractor is hot.
75 Tips
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top