8 N cuts out, then runs fine

Having a problem with my 8n. I have replaced the front mount distributor, points plugs, ignition switch, new main resistor and new In line resistor, It ran fine but last fall it got hard to start. Put a jumper wire across the in line resistor and it started right up. Take the jumper wire off and it ran fine, it even would start without it. Now it runs ok for a while, the starts to cut out and seems to run on about 1 or 2 cylinders, it is worse under load., the it will come out,of it and run ok. When it is missing it spews water out the radiator cap but it is not hot. I know I overfilled it but funny it spews only when missfiring. When I put the jumper wire back on the resistor it seems to run ok. This is the second in line resistor I have put on it, rated at 1.2 ohms. It seems like this is electrical, but could it be fuel related? Any suggestions?
 
Just some friendly advice here; never just start replacing parts without first knowing the true root cause of the problem. Chances are some or maybe all the parts you replaced were fine as they were. Also, overfilling the radiator is a no-no and overheating may be a contributor to your electrical issues -water will conduct electricity and an overheating radiator can spew coolant into the distributor. We've concluded you have a 12-volt 'conversion' and I use the term loosely because so many 12-volt changeover jobs are done incorrectly. 99.98% of the time they are wired wrong. There is an excellent document created by long time member JMOR called "WIRING PICTOGRAMS" by JMOR, and shows all the correct ways to wire these old N's, whether 6-volts or 12-volts. You can get a free download of it at the NTC web site. Find your set up and verify it is correct with no deviations. It has been proven here by Bruce and few others that the external resistor sold for use with the 6-volt coil in 12-volt changeover jobs have values all over the place. Don't just assume because the package states it is rated at 1.2 OHMS that it is. Use your ohmmeter and verify it. Answer these questions: Is your alternator 1-wire or 3-wire? Is the original voltage regulator removed from the circuit? When it is running, what does the ammeter show? Are there lights in the system? When it becomes 'hard to start' does the engine crank, just not catch? How old is the battery? I suggest to go slow with a step-by-step problem solving procedure by first disconnecting the battery and taking it in to a local shop and get it tested. While power is off/disconnected, start tracing wires per PICTOGRAMS and the I&T F-04 Manual. having the original wiring correct to the ballast resistor is important. Start here and report back with results...

Tim *PloughNman* Daley(MI)
 

bruce, i had this same issue last summer. as u may recall, i've been running my 6 volt coil on 12 volts without an added ceramic blob.

last summer, it started acting like the OP describes. i had been waiting for that moment before i bought a 12 volt coil. the punchline is: when i put the 12 volt coil on, it continued to do the same thing.

this winter i replaced the ignition switch and the condenser. if those don't prove to have cured it, i guess the OEM ballast resistor is the next suspect.
 
Found the culprit. Bad hot post on coil. I had put all those new parts on last spring and everything was working fine until last fall whe it started acting up. I had already purchased a 12 volt coil, just never put it on, the 6 volt was working ok. When I was taking the wire off the coil, notice the post was loose, The coil was cracked around the post. Guess it was making a connection part of the time. New 12 volt coil works fine, so far. Thanks for the advice.
 
Well back to the drawing board 12 volt coil did not fix the problem. It appears now that when the switch is turned on there is power to one side of the ballast resistor, but not to the other side, which goes to the coil. Put a jumper wire across the resistor and it starts right up. Odd that sometimes it will start without the jumper wire and sometimes it won't. Had put a new ballast resistor on a year ago. Guess I will be getting another new one and see if that helps. I did away with the secondary resistor after putting on the 12 volt coil. Was that the right thing to do? Suggestions appreciated. Thanks.
 
(quoted from post at 21:30:46 05/27/18) Well back to the drawing board 12 volt coil did not fix the problem. It appears now that when the switch is turned on there is power to one side of the ballast resistor, but not to the other side, which goes to the coil. Put a jumper wire across the resistor and it starts right up. Odd that sometimes it will start without the jumper wire and sometimes it won't. Had put a new ballast resistor on a year ago. Guess I will be getting another new one and see if that helps.
This type of failure is called an "intermittent". It's not unusual - what's happening is that there's a break in the resistor someplace. As it moves from engine vibration (and other causes) it sometimes makes the connection and sometimes breaks the connection.

(quoted from post at 21:30:46 05/27/18) I did away with the secondary resistor after putting on the 12 volt coil. Was that the right thing to do? Suggestions appreciated. Thanks.
Yes. A 12 Volt coil only needs the original ballast resistor, not the additional resistor.
 

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