8N died won't start

[Eric L]

1948 8N front mount distributor. Just today i was letting my 8 idle and it died and then it wouldnt start back up.I check the fuel at the carb. and it is getting fuel,i also used the alligator clips to jump the electric button still no luck.I took the coil off the dist. cap and it had spark because i got shocked!!!!Im not sure what the problem is. If anyone one could help me it would be greatly appreciated.Thanks!

 

[Bruce (VA)]

It is important for you to tell us if your tractor has a 6 volt or 12 volt electrical system. The troubleshooting is different based upon the configuration of your engine.

You've got the right idea about what to check, but you didn't say exactly how you checked for spark & fuel or what the ammeter needle was doing while you were cranking the engine.

Remove the bolt in the bottom of the carb; as long as the fuel is turned on, you should see gas flowing out of the carb. If it’s a dribble, or runs for 5 seconds & stops, or none at all, you have solved half the problem: it’s fuel related.

What is the ammeter doing? Does it show a constant discharge, no movement at all, or does it dip? Next, get an old plug, open the gap to at least 3/16" (1/4" is better) ground it to a rust & paint free spot on the engine, turn the key on & crank the engine. If the spark jumps the 3/16” gap, you probably don’t have a spark problem. If it won’t jump the 3/16” gap, you have a spark problem. If the ammeter shows a constant discharge, or doesn’t move at all, that also tells you that you have a spark problem.

There are ways to check for spark & fuel that work & ways that don't; how did you make the checks? For example, having gas to the carb is nice, but having it past the float is what counts! That’s why removing the bolt in the bottom of the carb is the way to do it. And, same thing w/ spark at the plugs. Some folks think that checking for spark means pulling a plug wire off & looking for one. Well, it's the distance the spark jumps at the plug that gives you the info you want. It takes about 17kv to jump a 3/16" gap & 22kv to jump ¼” in the open air, so that's why you need to use a spark plug. Or, a store bought plug checker. Remember, it’s 14psi outside of the engine & about 90psi at a 6:1 compression ratio in the cylinders & compressed air crates electrical resistance, so you really need the 17-22kv to fire the plugs when the engine is running. There are other good ways to check for fuel & spark, but these ways work for me.
50 Tips

 

[Eric L]

Well Bruce i did check for fuel at the bottom of the carb. and it has fuel coming out,as for the ammemeter it does nothing when i crank the engine.I also check for the spark at 3/16 and it has no spark what so ever.Oh yea by the way it is a 6 volt system.

 

[old]

The way you wrote your post it is hard to understand what you are in fact saying. So does the engine turn over when you hit the starter button or does it do nothing?? If in fact the engine spins but does not start do you have a nice blue white spark that will jump a gap of 3/16 or more?? As as Bruce has said you need to tell us more so we can help you help your self.

 

[Tom N MS]

Spark to coil but none at plugs..Next thing to check is the points.

 

[Bruce (VA)]

I’ll assume that if you have a 60+ year old tractor that you have a test meter.

I have discovered that 75% of “no spark” problems on frontmounts are as a result of poorly aligned parts or wires & not parts failures. Remember, you are dealing w/ parts made over 60 years ago that have seen a lot of wear & tear. They just don’t fit together like they used to.

Check for voltage at the top of the coil. Battery voltage w/ the points open & about half of that when they are closed. If you do not have voltage to the coil, then move upstream to the resistor then to the ignition switch. As you check each component, wiggle it & the wires attached to it & watch you meter. Resistors break or get shorted & wires corrode.

If the voltage never drops when the engine is cranking, that means the points are not closing or you have lost contact between the pigtail & the brass screw or the tab & the cap.

Next, pull the distributor & check the points; are they burned, pitted or mis-aligned? Check the point gap, .015 on all four lobes.

Next, with the distributor still off the tractor, install the coil. Look at the pigtail on the coil; is it touching the brass screw w/ the concave head inside of the distributor? Don’t trust your eyes; test for continuity from the top of the coil to the points. If you do not have continuity, stretch the pigtail a bit until you do. (some people would rather put a small washer under the brass screw) Make sure that the pigtail is not grounded to the clip that holds the distributor plate in place; sometimes you can move the plate while setting the timing & actually ground the pigtail. Your meter should tell you this even if your eyes don’t! Also, look at the little tab opposite of the pigtail; bend it a bit also to insure that it will contact the distributor cap. Another common failure point is the insulator in the tab on the distributor plate where the brass screw w/ the concave head goes; it holds the copper strip from the points. Again, your meter will usually tell you if you have a problem, but you might have to wiggle the copper strip a bit. Once you are sure that you have good continuity inside the distributor, you should be good to go.

At this point, I just put the distributor, coil & cap all back on the tractor as a unit (it helps to do this from the left side). The reason I do this is because it is real easy to get the cap or coil mis-aligned trying to put it back together one piece at a time & the result is something gets broken or you get a ‘no spark’ problem.

Post back w/ results & any other questions.
50 Tips

 

[Eric L]

Ok will check all those things and get back to you.I appreciate the help u have given me!!!

 

[Sweating in Florida]

I had a problem like it, was a broken wire connection on the inside so I could not see it. Check for voltage at the coil as Bruce says and work your way back to the key switch. Move some wires to see if it changes. A simple test light works well for that. Good luck.