48 8n stopped running

mdgriess

New User
Well my 8n dug about 100 post holes yesterday perfectly. I gassed her up and put her away. Today when I started her she ran terribly and started backfiring. I drove her back up to the shop and turned her off and then I couldn't get her to start again.
Don't know if it matters but i replaced the coil and distributor cap a week ago and correctly gapped the points. I have six volts to the top of the coil but no spark. Could the coil have gone bust already?
 
Could it?

why nit check spark vs guessing. If spark is good go for a quickie comp test, never know, mighta hung a valve
 
" Could the coil have gone bust already? "

Probably not.

Why did you replace it in the first place?

Pull the distributor & find the problem.

Assuming that the bushings & advance weights are ok (*see below), & that you have correct voltage to the coil (battery voltage with the points open and about half that with the points closed), the most common electrical failure (no spark, weak spark) points on the front mount 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) If you need to replace the insulator, use a .250 x 3/8 nylon square nylon anchor nut available at most big box home stores

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. I use only Wells, Blue Streak or Echlin brand points (* *see below).

10. Burned rotor, cracked/carbon tracked cap.

After find the problem & re-check the point gap, do a continuity check before you put the distributor back on the tractor. Before you start, make sure your meter/light works.

With the distributor still off the tractor, 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. Put the coil on the distributor, 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 misaligned 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. Whatever 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). 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. Hand tighten the two bolts until the distributor body is flush with the timing gear cover.

Post back w/ results or more questions.



* Unscrew the plate hold down screw & remove the C clip to get the plate out. Remove the shaft & weights. The weights should freely move.

* *NAPA part numbers:

• Points: FD-6769X
• Condenser: FD-71
• Rotor: FD-104
• Cap: FD-126
75 Tips
 
ok a little info. Tractor sat for 20 years then ran for a summer or two and then sat for another few years. Then it came to me for "free" The distributor cap was broken and the points were pretty bad. so i rebuilt the distributor. she ran great yesterday.I went through your whole list of checks and everything is a ok. just noticed fuel dripping from the air inlet on the carb. and the choke wasn't on. Would I have an issue with that now?
 
well she most definately has spark. I went out and check in the dark to be sure it was a a strong spark jumped a good quarter inch. so now I am thinking its in the fuel somewhere. I will check the fuel screens tomorrow and post results.
 
if fuelis leaking from the carb and this was not just after a failed start attempt, then the flaot valve may be leakin.

do a flow test thru bowl into a jar and see if you have good flow for at least 30-40 seconds into a jar.
 
well i got the carb off and looked in the tubes it had no choke retainer spring, thick varnish everywhere, choke plate spring frozen closed, gummed up idle jet, and overall neglect. good thing that i have a new Holland dealer 30 miles from my house. Complete rebuild kit was in stock and my carb is disassembled in a can of carb cleaner as we speak. hopefully this fixes the issue of no fuel delivery because the spark issue was fixed.
Thanks a ton bruce for the distributer check sheet. upon reassembly she worked great.
 
(quoted from post at 23:04:17 04/18/14) well i got the carb off and looked in the tubes it had no choke retainer spring, thick varnish everywhere, choke plate spring frozen closed, gummed up idle jet, and overall neglect. good thing that i have a new Holland dealer 30 miles from my house. Complete rebuild kit was in stock and my carb is disassembled in a can of carb cleaner as we speak. hopefully this fixes the issue of no fuel delivery because the spark issue was fixed.
Thanks a ton bruce for the distributer check sheet. upon reassembly she worked great.

You're welcome. Glad to help. Post back when you get it running.
 
As simple as these little units are they sure keep you on your toes as far as trouble shooting a problem. Sure glad they don't have wings or we would be doing lots of "off airport" landings. ]
 
well.... it was the coil. but now I have a distributor I rebuilt twice, new plug wires, new battery, new plugs, and a completely rebuilt carb. kind of felt stupid when i finally replaced the coil and she started right up. but oh well now she runs better than ever and I know how to fix a lot more than I did before.
 

" well.... it was the coil."

I don't think so. That's because you said:

" I have six volts to the top of the coil but no spark."

Followed by: " well she most definately has spark. I went out and check in the dark to be sure it was a a strong spark jumped a good quarter inch. "

So, replaced the coil & now it runs, right? And that was the reason you concluded the coil was bad?

Do us a favor........put the old coil back on & see what happens!
 
well it was the new coil i bought. the original still worked also. I put the original back on and kept the second new one on the shelf as a back up. I will no longer go to tractor supply for parts. Thanks for all the help though. The old girl runs better than I have ever seen it go. I don't even need to choke her to start any more.
 

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