8n fires up only after releasing the starter button

Hi guys, i"m new to the forums but have browsed a while, and could not find the answer to my issue. I have a 1948 Ford 8N - with the front mount distributor. Was converted over to 12 volts years ago, runs/charges fine with no issues. This tractor is new to us. The only problem i can see is that the engine will only fire up and run AFTER the starter button is released. If you hold the button it will crank all day and never start, but crank for a few seconds and let it go, and she fires up every time. What could cause this problem? Like i"ve mentioned before, the tractor runs great, no issues with the charging system or anything like that.

You hardly ever have to use the choke, it just starts right up, but ONLY when you let go of the OEM starter button. Thanks for your help

You have a weak spark. The starter is pulling all the current out of the battery & and soon as you let off the button, you've got enough current for the ignition circuit.

There are a number of things that can cause a weak spark, so start w/ the most common & easiest to check causes.

First, put your battery on a charger (see tip # 60)

You need a strong battery to:

1. Close the solenoid

2. Spin the starter

3. Engage the bendix

4. Provide voltage to the coil.

As the battery gets weaker, the first thing to fail is your spark. If the battery is almost totally dead, all you will hear is the solenoid clicking.

In addition to charging the battery, chances are you need new cables as well (tip # 41). And, don't forget to clean all the grounds, to include the mating area between the starter & the block.

The more current you use to spin the starter, the less you have for the ignition.

After the battery is fully charged, check it per tip # 49.

If you have new cables, a good battery fully charged & clean grounds, move on to the other possibilities (dragging starter, other wiring problems, etc)

Post back w/ results or more questions.
75 Tips

try this test.

pull your truck up to the tractor.

run a jump cable from your truck battery to tractor.

ground them the same polarity. IE.. truck negative to tractor negative.. etc. and wire the bat hot right to the coil.

now hit the tractor start button as you normally would to start her.. see if she fires right off.

has she started fine befor enad just started doing this.. or did you rewire something recently?

I too agree weak spark due to a problem like the starter getting bad and drawing to many amps. Or maybe poor connections

My 8N side mount did same thing when I got it.

Problem was it had a 12 volt conversion kit with the kit supplied ballast resistor. Problem was the resistor measured 5.6 ohms. I replaced it with a 1.5 ohm resistor and cured the problem.

My brother got a new to him Jubilee with same problem, same cause and same cure.

If you have an extra resistor, check it's value.

I've only owned the tractor for two weeks. The previous owners had it at a farm, where they used it to pull a small brush hog. It ran and performed well, no issues. Since i've gotten it i've also done nothing to it, it is in good shape body wise and mechanically.

One thing i do notice, is there is a ballast resistor installed on the firewall - one of the porcelain kind like in an old Chrysler car. I wonder if the ballast resistor is affecting the starting. I am told that when these tractors are turned over to 12 volts (as this one was), this resistor is essential. Haven't tried the jump start with the truck yet, but will post later with the results.

I hope this isn't a serious problem because i've almost learned how to "time" the release of the button, and the tractor runs and works so well. there has never been a time where i haven't been able to get it started.

Hatchetman........sounds like you gottchur ignition source connected to the little terminal of yer starter solenoid. The starter solenoid is GROUNDED (activated) by the BIG thumb switch by the tranny shifter. When you remove yer thumb from the tranny shifter button, you now have volts to the LITTLE middle terminal of yer starter solenoid which will now run yer ignition.

Many shade tree mechanics install the 8N's starter solenoid BACKASSWARD so the little middle terminal faces outwards and eazy to gitt too. Thats the WRONG way. The little middle terminal must face the engine block. You do not haffta remove the starter motor, just undue all the solenoid connections and turner round. Simple, eh? ........dyslectic Dell

" is there is a ballast resistor installed on the firewall - one of the porcelain kind "

That's not a ballast resistor. It's a fixed resistor.

The picture is the OEM ballast resistor. It changes value when it gets hot, unlike a fixed resistor. It's .03 ohms cold & 1.7 ohms hot.

" I am told that when these tractors are turned over to 12 volts (as this one was), this resistor is essential. "

Yep, plenty of people believe that. And it's applicable only if you use the 6v coil. And, chances are even then, the fixed resistor has to much resistance because no one thought to actually measure the coil before slapping some resistor in the circuit. See tip # 30 at the link; all you need is a 12v coil & the OEM ballast resistor.

75 Tips

Like the garment.... It depends.

What coil and what resistor

Listen carefully to what Soundguy and Bruce told you. If you have a 12 volt conversion, put a 12 volt coil on it and ditch the extra ceramic resistor. But you do need the original ballast resistor as Bruce pictured.

(quoted from post at 16:47:48 08/26/14) Listen carefully to what Soundguy and Bruce told you. If you have a 12 volt conversion, put a 12 volt coil on it and ditch the extra ceramic resistor. But you do need the original ballast resistor as Bruce pictured.

Click to expand...

I'm going to order the OEM Ballast resistor that is in the picture, and go from there. I will let everyone know the results. Thanks everybody for helping me. I greatly respect everyone's opinions here on this board. Lots of knowledgeable folks here.

" I'm going to order the OEM Ballast resistor "

What about your coil?

If your coil measures 2.5 ohms or more, you do not need to replace it. Otherwise, you will also need a 12 volt coil, (i.e., a coil w/ 2.5 ohms or more internal resistance)
75 Tips

Sorry Bruce - i neglected to add that my tractor right now has the 12 volt "Square Can" Coil.

(quoted from post at 12:10:09 08/27/14)
Sorry Bruce - i neglected to add that my tractor right now has the 12 volt "Square Can" Coil.

Click to expand...

How do you know it's a 12 volt coil ?

Because i ordered it from here when I gave the tractor a tuneup two weeks ago when i first got it (New points, condenser, plugs, plug wires, new coil, cap, oil change, etc..)