# Ford 3400 wiring issue



## csd (Dec 6, 2010)

I just purchased a Ford 3400 tractor. I had some issues with the wiring and found bare wires and dead ends so I decided to replace the entire wiring harness. This solved a couple of the problems I was having but now after the tractor has been running for a while it starts to backfire under load and will sometimes cut out. The coil is cool to the touch but I am thinking it may be the problem. It also seems to run better with the choke pulled out a ways. I am still convinced it is electrical rather than fuel but not 100% sure. 

I also have a mystery wire running from my starter relay to the coil. I have no idea why it’s there and it isn’t on any wiring diagram I have seen for the tractor. It ties in with the coil wire coming from the key switch. When I un-hook it the tractor will still run but runs even rougher.

Any ideas?

Thanks!


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## Tom_Carr (Dec 24, 2012)

The choke is actually an enrichment device that changes the fuel/air mixture rather than cut off air supply like a coinventional choke lever. So the enrichment should be pulled out some to achieve the proper mixture when warmed up. It will rum rich whem pulled out and lean when pushed in.

I can't help with the wiring issue. I have some myself I trying to figure out.


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## sixbales (May 18, 2011)

You probably have a 6v coil. Most likely, the wire from the ignition switch to the coil was a resistor wire to reduce the voltage from 12v to 6v for the 6 volt coil. 

The wire from the solenoid to coil provides 12 volts to the 6v coil to give a hotter spark for STARTING only. Actually, it's a good idea. But it should be tied to the start/crank function only. If you are not cranking, it should have no affect, so if you are noting a difference, you've got a wiring problem. 

You may have burned the points. I would put the resistor wire back on it and replace the points (if they are burned). 

Hope this makes sense to you. Please feel free to ask questions


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