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1939 9n running rough

Tyler w Hey guys. The key switch on my 9n was all corroded and not connecting right, so i went to tractor supply and put a universal one in. I had done this over the winter with the other switch due to the same problem. Now it idles fine at low rpm's, but when i increase rpm's, it runs really rough and skips a lot. But when the choke is held out, it runs fine and doesnt skip a beat. Will barely move itself without choke being held out. It ran fine with the other switch, i just had to keep pressure on the cnatacts with the key. I made sure i put the same wires on the same terminals as previous. It has spark to all cylinders. So what could be the issue? Please help!
mark sr The key switch on my NAA came from TSC. The 1st one I got was defective and I had to return it, the replacement has been on there for 6-7 yrs.

I'd bypass the switch and see how it runs, that way you can find out if it is the switch or something else. My faulty switch made my tractor quit running altogether.

Ed sounds more like an adequate gas flow to me,,,if you have to keep choke out then its niot getting the right amount if fuel...check all your filters ,,,bad switch has nothing to do with having to choke it
Jim Loveridge After you prove the switch good or bad like Mark said, double check the firing order first. 1-2-4-3 front to back. If that's correct you can check for good fuel flow by removing the plug at the bottom of the carburator and see if you can fill a pint jar in 2 to 3 minutes. You say you have spark at all cylinders, but is it a good strong blue spark. Are the plugs clean? Having to keep the choke out can be caused by a weak spark also. In my opinion, 90% of the time, the problem is ignition.
Tylwe W I checked gas flow. Was a little dirty but nothing enough to affect carb. How do i bypass the key switch?
Bob G Dirty fuel? bet your main jet is partially plugged. It does not take much.
Tyler W My dad (who was a mechanic) and I took the carb apart and cleaned it. We put it back on and still the same problem.
Bob G A normal ignition switch has two terminals, to by pass it you just jump between the two with a wire. clips works good. If it has more than two wires, then I don't have a clue what you have.
sure would be intersting to see in person what is going on. real hard to troubleshoot this way, but we try.

Bob G is this a 6 volot system or 12? Is the ballast resistor wired in right? if 12 does it have a12 volt coil or 6 volt? If 6 does it have the estra resistor to limit current flow thru coil?

just thinking.

Tyler W It is a 12 volt system. We checked system with a test light, and the light was bright at the terminal going into the resistor. At the terminal coming out of the resistor, the light is very dim, and it is very dim at the distributor. Is this normal, or is the resistor bad?
BOb G with the points open or the wire to dist disconnected you should have battery voltage at top of coil. with points closed about half. voltage only tells part of the issue. current flow is what matters, a 6 volt coil should have about 1.5 ohms of resistance and a 12 volt one about 2.5 ohms. if you are getting current low thru the orginial ballast resister it is probably good. if you can check for voltage. a test light provides a ground and then you have current flow and the resistor will reduce current flow giving you a dim test light.

do a goole search for ford 12 volt wiring diagram. it may help you.
you need to know if you have a 12 volt or 6 volt coil to figure out what rewsistors you need in the wire.

Jim Owen Have you checked the dist. cap? Make sure the rotor is not hitting the contacts in the cap. Also check for cracks in the cap.
Are the plug wires good? These old tractors with the front dist. are bad about the pug wires getting hit by the Alt. belt.



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