Timmy S

New User
I have a 8n that runs well for around hour after that it starts like it is running out of gas. It will cut off and will continue running that way until you let it sit for a while. Afterwards, it will run for around another hour and starts doing it again.

I can't figure out whats going on.
Any help will be appreciate.
 
Welcome to the forum!
Are you sure it's a 1951?
Does it have a front mount or side mount distributor?
It does make a big difference in what could be wrong.
In either case, when it quits, does it still have good spark
at the plugs? Should be a good blue/white color when checked.
If it has good spark, you could check fuel flow from the bottom
of the carb drain. It should flow steady, not dribble out.
Both need to be checked right at the moment of stall.
It would also help to know if it has been converted to 12 volts,
has an Electronic Ignition, etc, but basic troubleshooting is still
spark-fuel-air at the right times.
Let us know! :)
 
Thanks Royse

Yes, according to the reference with the serial number it is a 51 side mount distributor. I did not check the plugs but did the fuel flow. That is what I first thought the problem was, but has good fuel flow. It has not been converted. It is a six volt still orignal. I want to keep it all orignial looking.
 
Next step would be to check the spark when it quits.
It's probably weak (yellow) or non-existant.
If no spark at plugs, check for spark at the coil wire.
How long do you have to let it cool before it will run again?
 
Royse,
I usually just let it sit until next day. I tried to start it hour later but it kept with same issue. Once I let it sit over night, it runs well for a while.

Do you think it possible be the coil?
 
Possibly. If it were a front mount coil I would be buying one.
But the side mount, round can coils do not fail as often.
They're pretty durable. If you have a spare around that you
could swap in, it would be worth the time to give it a try.
I'm hard pressed to say spend money on one when we don't
even know if the spark is good or bad yet.
I can't see spending money on a guess when we have a chance
to prove or dis-prove it first.
 
Timmy S, Next time it gives you problems, loosen the gas cap, and see if there might be a vacume in the tank. If so, the vent is probably plugged up. It"s on the top side of the tank, and you have to remove the tank to get to it. One other thing, if it"s not running is to take a little jumper wire and jump across the ignition switch and see if it runs. If so, the ignition switch is getting hot and breaking contact. Replace it if it doesn"t have continuiity through the switch. Best of Luck!!!
Dave
 
Timmy, Royse probably pretty much nailed it with the tank vent or even more likely the ignition switch: they are famous for that!
Only thing I can ad to what has already been suggested is: Is your fuel bowl clean? I have seen where sediment gets bad enough that it starves, then after a while enough fuel works through for another while. The other thing to keep in mind (this drove me nuts on my JD70) is condenser, I honestly never considered it at first as I have never had one that would go bad intermittently, in my past they were either good or bad, but after eliminating EVERY other option, including wiring in a back up coil, I finally tried the condenser...been fine ever since!
 
Timmy.......in late 1950, Ford changed from the weird 4-nipple frontmount dizzy to the more conventional 5-nipple sidemount. You can count nipples, can't you???

The weird 4-nipple dizzy has a 1-terminal squarecan ignition coil with insulative tar that melts after about 1-hr of running time. It takes about 4-hrs of cool-down or overnite for the tar to re-solidify so you can run again fer about 1-hr. Unfortunately, there is NO eazy cure for this problem. Many desperate frontmount owners "hogg-outt" the squarecan coil and wire in the more reliable roundcan coil. Remember, the squarecan coil NEEDS the MANDATORY "infamous ballast resistor" (mounted on the dash underneath the ammeter) Many N-owners "by-pass" this resistor for hotter sparkies and eazier starting. But guess what, that also causes the insulative tar to melt and makes weaker sparkies. DON'T DO IT.

Remember ittza 2-bolt, 15-min job to remove the frontmount dizzy and change the points (0.015") on the kitchen table. Just un-snapple yer capple and walk. Installation is a reversal of the removal ...except... finger start the 2-bolts and then install the rotor. Now rotate the rotor until the OFFSET drive tang fits the OFFSET camshaft drive slot. Now tighten the 2-bolts and re-snapple yer capple and yer good to go. Simple, eh?

Remember to POLISH the INVISIBLE CORROSION from between the points (0.015") after installation. Me? I clamp a $1-bill between the points and pull. Iff'n yer really cheap, tear a strip from HEAVY brown paper grocery sack and use that. ........HTH, Dell, yer self-appointed sparkie-meister
 
As others are saying, you need to narrow the problem down to spark or fuel.

It takes three things for an engine to run: spark at the right time, compression, & fuel in the right mixture. For the moment, forget about compression & concentrate on narrowing the problem down to spark or fuel.

There are three very important tools you always need to have in your N tool box: a 3 inch piece of wire w/ alligator clips on each end, an old spark plug w/ the gap opened to at least 3/16” ( ¼” is better) and a 7/16 box end wrench. (see tip # 50 at the link below) And, you really do need a working ammeter on the tractor; it is a very important diagnostic tool. With these tools, you can quickly narrow down most N problems to spark or fuel.

Next time it stops, check quickly for fuel then spark. When I say quickly, I mean get off the seat, grab the tools & do it right then. Do not wait a minute or two. First, check for fuel. Get a can & put it under the carb. 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. Let it run for at least 30 seconds. 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. If gas flows well out of the carb & only stops when you turn it off at the sediment bowl, chances are very good it’s not a fuel problem. So, next, turn the key on, crank the engine & look at the ammeter. What is the needle doing? Does it show a constant discharge, no movement at all, or does it move back & forth slightly? Next, get the old plug, 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 needle shows a constant discharge, or doesn’t move at all, that also tells you that you have a spark problem. Jump the ignition switch w/ your jumper wire & see what happens. If it runs, you found the problem. If it doesn’t have spark after you jump the ignition switch, post back for more info on further troubleshooting. (and do not forget to turn the ignition switch off; see tip # 38)

If it does not have gas coming out of the carb at a steady stream w/ the bolt out for at least 30 seconds, you have a fuel problem. First, remove the gas cap. Your vent could be clogged & it vacuum locked. If that doesn’t work, tap the carb bowl w/ a hammer handle in case the float is sticking closed. (don’t whack it w/ the head of the hammer; you can crack the bowl). If you still don’t see gas flowing, the N has three fuel screens; one in the brass elbow, one in the top of the sediment bowl & one on the stem of the sediment bowl in the gas tank. Check the screen in the elbow & the screen in the top of the sediment bowl. (don’t worry about the one in the tank) Both probably need to be cleaned. If you have the fuel knob turned on all the way, & 1 gallon or less in the tank, it may be trying to feed off of the reserve inlet which is probably clogged. Only open it 2 full turns. Put at least 2 gallons in the tank. (and do not forget to turn the gas off; see tip # 9)

There are ways to check for spark & fuel that work & ways that don't. For example, having gas to the carb is nice, but having it past the float is what counts! That’s why removing the 7/16” bolt in the bottom of the carb is the way to check for fuel. 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. Remember, it’s 14psi outside of the engine & about 90psi at a 6:1 compression ratio in the cylinders & compressed air creates electrical resistance, so you really need the 17-22kv to fire the plugs when the engine is running. A store bought plug checker will work better than an old plug because it won’t shock the snot out of you like an old plug might!
75 Tips
 
" it sounds like the carb needs to be rebuilt"

Hmmmmm.....


He said " I have a 8n that runs well for around hour "

So, it starts ok, runs an hour, stops running....then restarts after setting.

What you are saying is that the carb is clean then gets dirty after an hour....then cleans itself after it sets a while. Right?

I must have missed that possibility somewhere in my experience. I've never seen a self-cleaning carb........
 
Dell, forget the insulative tar bit.Wire used to wind coils and motors has a coating on it.One is called Formvar.After a motor is wound it is dipped in formvar and baked.It is said that a motor winding would vibrate and destroy the coating.The tar or pitch was put inside the Ford coils to keep the windings from moving around and shorting the turns.Epoxy is used now in china made coils.
 

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