8N doesn't start

CraigM · Dec 30, 2009

The tractor stopped working last year. It had spark, so tore into the fuel system and found it plugged by all kinds of gunk. Cleaned out the line from tank to carb, and the carb itself. Replaced the gaskets and reasembled. Fuel comes out of the carb drain, so it's getting that far. Pulled the rear spark plug after a few minutes (not continuous) of cranking and it didn't seem wet at all, and didn't smell of gas. Shot a small amount of ether starting fluid directly into the spark plug hole, reasembled...nothing. That plug would spark if connected to the wire and laid against a ground, so I know it's getting a spark. Checked the next one forward out of curiosity, and it is working also. Getting desperate now, so seperated the carb from the manifold a little and shot more than a little ether into it by putting a WD-40 'straw' onto the ether can and slipping it between the seperated pieces. Tightened it up and tried again. Not even a poof.

So, it seeems to be getting a spark, but won't even sputter with ether. Any suggestions?

DJ54 · Dec 30, 2009

If it had that much gunk in the system, it may have sucked it into the jets, and have them plugged. I'd pull the carb., drop the bowl, remove the jets, and give it a good cleaning with spray carb cleaner. Just be sure and turn your head, or wear safety glasses when you give it a shot.

You may want to try and put a dab of gas in the cylinder, and try that. About 1/4 of a cap full from a plastic soda bottle should be plenty. The ether may be evaporating before you get the plug in. Although it should do something if sprayed in the intake. You'll dry your cylinder walls out if you use too much. It is a last ditch effort around here..

Maybe before even trying that, check your air filter, mice have been known to build in those oil bath filters.

It all boils down to the checking the basics.. Air, fuel, and spark. If you have all three, it should at least give you a "pop"...

J_J · Dec 30, 2009

If your compression is good, and the valves are not stuck, then with spark and gas/ether, it should fire.

Does it have suction on the carb when you crank. Are you trying to do this by your self.

Take all the plugs out and do a compression test, and write down the results. You said all plugs were firing. Is the fuel fresh? Is the shut off valve on. I have to turn mine off after I stop for the day. . The carb drips even after rebuilding.

Egon · Dec 30, 2009

Screw out the carb jets, turn it over a few times and then set jets to where they should be. May have to make some adjustments to them afterward.

If possible give the jet screw holes a blast of compressed air.

CraigM · Dec 30, 2009

I've already done most of all that. Blew out the carb and all the passages before reassembling, checked the air cleaner, no mice or other stuff, it's got fresh fuel, it will suck a paper towel into the intake on the side of the hood when cranking, fuel shutoff is on and I have a helper. I wondered about the ether evaporating before getting the plug back in, that's why I tried seperating the carb from the manifold and spraying it into the air passage. Thre was enough there not to evaporate, and if it did, it should have just stayed in the plumbing. Have not done compression check. It ran before, there is no good reason to think that it suddenly doesn't have enough compression to at least sputter. Yes, I don't want to bother with compression checks. My mind was running on this while I ran a few errands and it almost has to be a fuel issue. I was headed back out to the shop and was going to try priming the carb with gas, but I like the idea of backing out the needle valves. Much easier. Can still prime it with gas if that doesn't work.

beenthere · Dec 30, 2009

If you put in starter fluid, and it wouldn't fire off, then I think you don't really have enough spark. Put a tsp of gas in each cylinder, the plugs back in, and turn it over. If spark isn't the problem, I think it will fire a bit but may not run.

You haven't said what you did with the coil, condenser and points, rotor cap, plug wires, condenser wire. ??
Replaced? Look ok? filed points? anything?

Buddy just worked on his 8N, and found that the replacement parts were defective (finally put in the old condenser, and got it running again).

And I'd only use ether in the air intake as I was cranking. Less chance of a big bang that way.

Soundguy · Dec 30, 2009

no cough on start fluid means no spark. or no compresion like a stuck intake valve.

comp is easy to check with your thumb and the plugs out.

spark should be bright and snappy and jump a 3/16 air gap.

If you have good spark, try new plugs.. sparking under compression with a near fouled plug is different than sparking in the open air.

fire order is 1-2-4-3

soundguy

CraigM · Dec 30, 2009

Ok, I've tried backing out the needle 2 turns and cranking. No luck. Tried a little gas directly into a cyl through the plug hole, no luck. Then we dropped the carb off the manifold and hung it there by the fuel line and a piece of wire. Hooked the large intake tube back to the carb and blew gently into it with the air hose using a rag to stop up most of the pipe around the air nozzle. Droplets of fuel came up out of the main jet, so the carb seems to be working. There was a little gas lying in the bottom of the carb when we took it off, consistent I guess with droplets drawn out by the engine but not sucked into a cylinder. We put the carb back with a pretty good load of starter fluid in the bottom, no luck. Yes, I know that's probably getting a little aggressive, but there is no good way to get the ether into the induction system through the air cleaner. About that time, I'm beginning to wonder if drawing a spark against the block may be different than with the plug installed. Thank you Soundguy, for confirming that. Seems like at least one should be able to at least make a sputter, but I gotta get this thing out of my shop so I'll be replacing the plugs next week, after the incoming cold snap clears out and I've had time to get to town.

As for the
>>coil, condenser and points, rotor cap, plug wires, condenser wire. ??
Replaced? Look ok? filed points? anything? <<

Haven't messed with any of it. They look ok. When we first started this, we checked for spark. It was bright blue and snappy. Since then it seems to vary a lot. Could be that I'm not picking good grounds to test against, or maybe those parts need replaced. If plugs don't solve the problem, I'll look at those other things more closely.

DJ54 · Dec 30, 2009

You may even want to pull the distributor cap, and look inside. Sometimes due to ionization there will be a buildup of matter on the lugs. I've had more problems with this on the newer aluminum lugs, than the old copper ones. It scrapes off pretty easy with a pocket knife.

Brighten up the rotor button too... Easy things to check...

If they would happen to be Champion brand plugs... We always had problems after putting in a new set. We found that it had to do with the coating that is put on them from the factory, and would cause carbon buildup. If you have one of those little sandblaster plug cleaners, you can clean them, and they will run a good while... I've had the same set in my Super C Farmall for 10+ years.