9n ignition

Glenn D

Member
Hi Folks.

Have a 9N with newly re-built Carb was starting and running for a few minutes then stalling, but would start up and run again. lots of gas flow, (carb worked fine in the 2N). Will recheck gas quality and flow when I go back. but after the last effort there is no spark. I suspect he coil or condenser is gone bad (front mount 12v conversion with 6v 1.5ohm coil) I also think that the spark advance isn't working, while it was running it wouldn't take any throttle adjustments it would only run at a fastish idle. I'm going back over there tonight and would like a list of checks to expose whatever is going on. I have a spare 6v could that is good.
 
no spark eh?

check power to the coil.

sound slike you should be using the oem ballast resistor plus another one if you are also using the oem 6v coil.

check to see if the poiunts have closed up.

put a test lamp inline with the coil. run engine over. should blink.

if it stays on.. you have a short in the dizzy.

if it never comes on.. points are not closing electrically.

improper, too close, points gap will show as burned points.

open condensor will show as burned points.

shorted condensor shorts points.

post back
 
"I suspect he coil or condenser is gone bad "

Probably not.

Coil problems are difficult to diagnose. For starters, round coils are pretty robust & square coils aren’t (because of the difference in insulation used), but neither one will hold up to a poorly done 12v conversion that allows too much current to the coil or leaving the key on (see tip # 38). Too much current creates heat which melts the insulation. Insufficient resistance in a 12v conversion will do the same thing. Rarely do coils just “go bad.”

As others have said, there are a few ways to see if a coil is bad, but it’s not possible to determine if a coil is good w/o some expensive testing equipment. If you detect a dead short or high resistance in the coil w/ an ohm meter, it’s bad. If it’s cracked, it’s bad. If a sidemount coil w/ battery voltage to the primary will not jump a ¼” gap from the secondary wire to the block, it’s bad. But, here is the hard part: even if you do not detect a short, even if it will produce a spark, even if it’s not cracked, that doesn’t mean the coil will work when it’s hot & under a load. So, it’s a process of elimination. If the tractor starts & runs fine for 30 minutes or an hour then cuts off & refuses to re-start, and you checked for spark at the plugs & it had no spark at all, AND you have the correct voltage at the coil that’s a good sign that you have a bad coil. Let it cool off, restart it & if you have a good spark, odds are it’s a bad coil. But, even then, you might end up w/ a spare coil on the shelf!

Bottom line.......coils do go bad, but I'll venture a guess that 75% of new N coils sold today are sold to folks who do not understand how to diagnose a poor spark problem or how a coil works. So, for those who don’t know any better, in a no spark situation the first suspect is usually the coil……and, more often than not, it isn’t the problem.

Or as one regular around here humorously suggested: "Well, it is like this...I don't know or really understand what that black thing does & I am suspicious of the unknown, so I think the problem is the black thing."

Before you check anything else, make sure you have the correct voltage at the top of the coil. It should be battery voltage w/ the points open & about half that w/ the points closed.

Assuming that the bushings & advance weights are ok, & that you have correct voltage to the coil, the most common electrical failure (no spark, weak spark) points on the frontmount are:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it’s fiber & will wear out; poke & prod w/ your meter leads to make sure it still works)

2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark.).

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks)

4. The condenser wire grounding to the plate or side of the distributor.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.)

6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o’clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o’clock)

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points.

10. Burned rotor, cracked/carbon tracked cap.

Unless the coil is cracked or shows a dead short, chances are it's fine; square coils rarely fail cold. Pull the distributor & do a continuity check.

First, make sure your meter/light works (don't ask....)

You can change points everyday & it will not fix bad bushings. If you are having trouble w/ points failure, check the shaft. If you detect movement, chances are it needs new bushings.

Inspect the points; if they are pitted or burned, replace them. Next, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. Make sure the points align correctly. Proper alignment is also critical to longevity. Look at the points when they are closed; both sides should mate evenly. Then, check the gap at .015 on the high point of all 4 cam lobes.

Now, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil mis-aligned trying to put it back together one piece at a time & the result is something gets broken or you get a ‘no spark’ problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. What ever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts) Then place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Then, hand tighten the two bolts until the distributor body is flush w/ the timing gear cover.

Finally, double check your firing order & plug wires. It’s 1-2-4-3, counterclockwise. It’s very easy to cross 3 & 4.

" I also think that the spark advance isn't working"

Pull the plate when the distributor is on the bench & check out the advance. Set the timing too. If you don't know how, just ask.

Post back w/ results & any other questions.
75 Tips
 
Coil has got power. only had a test light with me yesterday and that a good tip on making it blink though. I can try that. there are 2 ballast resisters on this engine and both were good. it was getting spark then suddenly it wasn't so something happened. All the parts are new in the distributor but I only replaced the points and gaskets myself I don't know the history or condition of the other parts. I do know the new points I found it with were installed wrong and of really poor quality. I also added plugs and wires to this engine.

The ballast resistors are both aftermarket ceramic types. one 1.5 ohm the other was 1.2 ohm I had previously tested them and the coil was 1.5ohm

(quoted from post at 08:49:14 06/17/13) no spark eh?

check power to the coil.

sound slike you should be using the oem ballast resistor plus another one if you are also using the oem 6v coil.

check to see if the poiunts have closed up.

put a test lamp inline with the coil. run engine over. should blink.

if it stays on.. you have a short in the dizzy.

if it never comes on.. points are not closing electrically.

improper, too close, points gap will show as burned points.

open condensor will show as burned points.

shorted condensor shorts points.

post back
 
"Well, it is like this...I don't know or really understand what that black thing does & I am suspicious of the unknown, so I think the problem is the black thing."

Heh! very good. One thing about coils is that they can suddenly be bad in just a moment after it was good.. same with the condenser but I've never seen either on new parts.


I will check that the problem is the unit is in a field on top of a windblown hill and the grass is almost 5' tall now so I usually carry in some stuff but not everything and last night I didn't have my meter with me (I was adding in the newly tested carb) just a test light but I did get a strong light and believe I have 12v there.

This is a good list that will keep me from forgetting anything, thanks


(quoted from post at 08:54:28 06/17/13) "I suspect he coil or condenser is gone bad "

Probably not.


Before you check anything else, make sure you have the correct voltage at the top of the coil. It should be battery voltage w/ the points open & about half that w/ the points closed.

Assuming that the bushings & advance weights are ok, & that you have correct voltage to the coil, the most common electrical failure (no spark, weak spark) points on the frontmount are:

1. The insulator under the brass concave head screw & where the copper strip attaches. (it’s fiber & will wear out; poke & prod w/ your meter leads to make sure it still works)

2. The pigtail at the bottom of the coil not making contact w/ the concave head brass screw inside the distributor. (With the coil on, the pigtail must firmly contact the brass screw. No contact = no spark.).

3. The copper strip is broken or grounded to the plate. (look very carefully for cracks & breaks)

4. The condenser wire grounding to the plate or side of the distributor.

5. The tab on the bottom of the coil not making contact w/ the brass button on the cap. (With the cap on, the tab must firmly contact the brass button. No contact = no spark.)

6. Incorrect positioning of the spring clip on the plate causing the pigtail to ground. (the open part of the clip goes between 7 & 9 o’clock on the plate. That puts the straight part of the clip opposite of the timing screw at 3 o’clock)

7. Incorrect seating of the coil on the distributor due to a loose bail or no gasket.(the coil must not move at all; if it does, replace the gasket or bail. Or stick some cardboard under the bail).

8. Water/moisture inside the cap due to gasket failure or the absence of a gasket. (the cap AND coil have gaskets)

9. Dirty/corroded/burned/incorrectly gapped or misaligned points.

10. Burned rotor, cracked/carbon tracked cap.

Unless the coil is cracked or shows a dead short, chances are it's fine; square coils rarely fail cold. Pull the distributor & do a continuity check.

First, make sure your meter/light works (don't ask....)

You can change points everyday & it will not fix bad bushings. If you are having trouble w/ points failure, check the shaft. If you detect movement, chances are it needs new bushings.

Inspect the points; if they are pitted or burned, replace them. Next, dress the points by running a piece of card stock or brown paper bag through them. New points sometimes have an anti-corrosive dielectric coating on them & old points can corrode or pick up grease from a dirty feeler gauge or excessive cam lubricant. Make sure the points align correctly. Proper alignment is also critical to longevity. Look at the points when they are closed; both sides should mate evenly. Then, check the gap at .015 on the high point of all 4 cam lobes.

Now, follow these steps:

1. Coil off, cap off, points open. One probe on the brass screw & the other on both sides of the open points. On the side closest to the cam, you should have continuity. Not on the other side! If you do, you will also have continuity everywhere because the points are grounded.

2. Coil off, cap off, points open. One probe on the brass screw & the other anywhere on the body of the distributor. You should have no continuity! Now, rotate the tang on the distributor....as the points open & close, you have continuity (closed) and lose it when they open.

3. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other on the cam side of the open points. You should have continuity!

4. Coil on, cap off, points open. One probe on the lead on the top of the coil, the other anywhere on the body of the distributor. You should have no continuity!

At this point, I just put the distributor, coil & cap all back on the tractor as a unit. The reason I do this is because it is real easy to get the cap or coil mis-aligned trying to put it back together one piece at a time & the result is something gets broken or you get a ‘no spark’ problem.

It's possible to put it back on wrong & break it. Look at the slot on the end of the cam shaft. What ever angle it happens to be, turn the distributor tang to match it. Make sure you can tell the wide side from the narrow side on both the cam & distributor! (close counts) Then place the distributor on the front of the engine, gently push it in place & slowly turn the distributor body until you feel the tang slip into the slot. Rotate the distributor body until the bolt holes line up. Then, hand tighten the two bolts until the distributor body is flush w/ the timing gear cover.

Finally, double check your firing order & plug wires. It’s 1-2-4-3, counterclockwise. It’s very easy to cross 3 & 4.

" I also think that the spark advance isn't working"

Pull the plate when the distributor is on the bench & check out the advance. Set the timing too. If you don't know how, just ask.

Post back w/ results & any other questions.
75 Tips
 
1.5 ohm 6v coil eh?

i think you may have a bit much primary resistance. i'm countinh 4.2 ohms. and that will make for about 2.85 amps

and since they are a plain cermaic type. they will be like that when cold.. menaing it may start hard. using the oem ballast resistor with it's thermal properties is usually more desireable, as it is lower ressitance when cold. still. if it WAS running with that setup. no need to muck with it. front coils are all over the place these days. I have seen plenty of 6v front coils that are .8-1 ohm.

1.5ohm is almost in sidemount 6v coil territory.. :)
 
" The ballast resistors are both aftermarket ceramic types. "

They aren't ballast resistors. They are fixed resistors. While they aren't causing the problem you have now, your life will be a lot simpler if you use a 12v coil & the OEM ballast resistor.

" only had a test light with me yesterday "

Take a meter w/ you. You need to measure voltage w/ the points open & closed.
75 Tips
 

Yes I thought since another post thread here said to keep it around 3.5a or lower then it would be safe so I left it like that.... it was starting ok just not running for long or tach-ing up. if I took one of them out. (I'll check the OE one, it's still under the dash but looks pretty bad and the one on the 2N was broken in half so I can't use that one) will it be ok at 4.4a ?
 
if it will 'start' like it is.. don't mess with it. starting will be the hardest part.. once started.. it should run fine.

again. if good spark on a cold start. go with it.
 

Welp turned out to be the breaker plate in the distributor is bad. it had some rust on it and the screw where the spring on the bottom of the coil broke out of the breaker plate. It was pretty clean by then I guess the PO cleaned it somehow but what was left was just too weak.

So the new breaker plates come with the nose bushing so while I'm there should I get the shaft and weights too? the shaft seems ok but the weights are pretty dirty and don't spring back like they should.
 
see if they will clean up and move freely. no need to spend money if you don't have to. if they turn out to be bad. of course replace them.. etc.
 
ok so the distributor (off the 2N) is on the 9n and working properly.

I now have the 9n distributor with new breaker plate installed on the 2n and the coil is bad (or condenser I guess). so now I have to put the old 2N 6v coil on there (because I have it) and it is 1.0 ohm, the only resister on the tractor is the 1.5ohm that came with the 12v conversion kit. The OEM resister was fried and unused. so 14.4/(1.5+1ohm) =5.75amps... is that too much for this old coil?

The coil I suspect is bad because the thing reads dead short and I found out the previous owner of the 9n let his brother in law take my resisters off and tried to start it until the battery was dead.. I found it the next evening with no spark and that's when I put the distributor from the 2n on it
 
About 20 to 25% too high, but if you NEVER leave ign sw on with a stalled engine, it will likely live a long life. (When actually running, the average current is about 1/3 rd of the off/stalled steady current.)
 

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