Ford 3400 running poorly

[Craig 59 641]

Repairing a ford 3400 for a friend. Was running poorly. Wouldn t rev up. Another person replaced the stock Holley carb with ?? Not sure of. Had a gas leak they thought it was carb. So replaced it. Still had a leak. Called me into help. Found leak in fuel pump. Replaced it. Ran better. But had a skip in idling. Ck points. They were worn down gap off. Bought ingnition rebuild kit. Cap,dust cover,points,condenser,wires and plugs. Installed them all, fired up tractor. Ran very nice. Idle fine and rev up. Warm up for a few minutes. Then put in gear to back out of barn. Started to cough & sputter. Not rev up. Ran very poorly. I did not replace the coil. Have one I bought. Not sure if this tractor is supposed to have a internally resisted coil or not. Couldn t find a resistor on tractor. Bought coil 12v with internal resistor. Is this correct for a 3400.
Also when I pulled the plugs they were white as a ghost. Makes me think it s starved for fuel at some point. But ran fine till reverse to back out of barn.
Any ideas we ll be helpful.
Considering to put original Holley carb back on after a good cleaning.

 

[Sean in PA]

That tractor originally had a resistance wire between the key switch and the coil. The resistance portion of the wire is thicker than the wire is at the coil and it looks like it is covered in heat shrink. If that resistance wire is no longer there then you should use a 12 volt coil that does not require an external resistor.

 

[Craig 59 641]

I m confused if resistor wire is missing. Then shouldn t I have a resistor external or coil with internal resistor.

 

[Tom in Mo.]

You are talking about out two very different systems. Fuel delivery and spark ignition.
One thing at a time. First thing I would do is make sure your fuel tank doesn't have debris sloshing around the bottom clogging the valve when tractor is moving. I have had many tractors with crud in the bottom of the fuel tank and it will make your tractor act as you describe.

 

[Sean in PA]

(quoted from post at 22:26:54 07/31/23) I m confused if resistor wire is missing. Then shouldn t I have a resistor external or coil with internal resistor.

What I meant was that if the resistance wire is missing then the coil should have been replaced at the time that the wire was removed to a coil that does not require and external resistor.

Also, there is no actual "resistor" in the coil. All coils have some amount of internal resistance due to the material used in the primary winding and number of turns in the winding. The resistance is designed to limit the current to the point where it can still deliver a good spark while reducing the wear on, and thereby increasing the lifetime of, the points. On old 6 volt systems the "sweet spot" of the resistance value was around 1.5 to 1.6 ohms, and on 12 volt systems it is around 3.0 to 3.2 ohms. When the manufacturers switched from 6 volt systems to 12 volt systems, some used the same coils that they had been using in 6 volt systems and they simply added an external resistor or resistance wire, while others switched to "true 12 volt coils" which had the proper internal resistance and did not require an external resistor on a 12 volt system, but they do not have an actual resistor inside the coil.

Before anyone jumps on me, I realize that some earlier engines, like the 9N/2N/8N tractors with the front mount distributor, did have a resistor inside the coil housing, but I am talking about modern coil design here.

 

[RedGreenGuy]

My 3400 did as you describe. Problem was rusty tank. Took to radiator shop that boiled it clean and double
lined it. Cost $285.00. Runs good now.