9n issues

[grandpa Love]

Our preacher bought a 9n and dropped it
off at our house for repair. Hadn't run
for years. Wife cleaned the carb and I
checked the wires and rigged a temporary
gas tank. It cranks and runs! BUT....we
noticed that the previous owner had
taken the knob off the choke and put a
stack of nuts and washers behind the
knob to hold choke 3/4 closed all the
time. We removed them, and quickly found
out they were still needed. Won't stay
running with out 3/4 choke. Throttle
doesn't have much affect on anything.
Only way to get it near full throttle is
to move lever in position and choke
it.... Then it revs up and runs good.
Adjusted carb all over the place. Didn't
help. Any ideas? Did dump transmission
fluid in the carb......boy did it
smoke!!! And then it started back firing
a lot, loudly. It also made the motor
run really fast even with throttle at
idle..... Never had one do that before.
But it did blow a lot of black crap out
on my white gravel! Any ideas?

 

[Royse]

Sounds like you have a fuel delivery problem.
Either gas to the carb or still though the carb after cleaning.
Check the fuel flow out of the drain plug on the bottom of the carb.
Should run a pint in about 2 minutes or less in a fairly steady
stream after the initial bowl empty happens.
If it doesn't, fuel tank, sediment bowl, screens, filters, lines, etc.

 

[Mad Farmer]

Not enough fuel or too much air. If carb/fuel delivery checks out O.K. look for a manifold leak. Does exhaust leak at manifold at all?

 

[TractorTucker]

Check if manifold is rotten causing a leak. Spray some carb cleaner on it while it's running, you should be able to notice if it has a leak.

 

[RM-MN]

You can buy a new carburetor for that tractor for under $50. How much time are you going to spend trying to get that one running.

 

[Phil N]

All the previous suggestions are very good. If you have a Marvel Shebbler or Zenith Carburetor, the cast
iron housings have passages that rust shut over time without use. There's one or two passages that go
through the gasket surface between the float bowl and main casting. They can rust over so you can't even
tell they are there. See attached picture. Totally disassemble carb and soak and wash in carb cleaner.
Poke through all the fine passages with fine wire like a strand from a wire brush. Blast carb cleaner
through the passages with aerosol can with fine straw. Repeat if needed. Blast all parts and passages with
compressed air. Assemble with a carb kit, install and adjust. Lightly bottom out mixture screws and back
out 1.5 turns to get started and the adjust mixture screws.

 

[Jim.ME]

If you don't already have a set of torch tip cleaners, pick a set up. That will give you a number of different size "wires" to match to the various orifice sizes for probing and cleaning the passages.

 

[grandpa Love]

I will add a bit more. My wife has cleaned and rebuilt 25-30 carbs....she uses torch tip cleaners. Carb cleaner spray. Air compressor. And always double checks herself against a diagram to be sure it's clean..... Because previous owner had the choke rigged closed I'm thinking bigger issue. Also....we have a spare carb for an N we tried and it acted the same. It was used on a running 8n last month. Will try spray around manifold later today.

 

[Jim.ME]

(quoted from post at 07:50:42 04/07/21) I will add a bit more. My wife has cleaned and rebuilt 25-30 carbs....she uses torch tip cleaners. Carb cleaner spray. Air compressor. And always double checks herself against a diagram to be sure it's clean..... Because previous owner had the choke rigged closed I'm thinking bigger issue. Also....we have a spare carb for an N we tried and it acted the same. It was used on a running 8n last month. Will try spray around manifold later today.

just mentioned the tip cleaners to be sure, sounds like she is doing it right with good results. That along with the carb swap points more towards the manifold being in question. Have you checked compression yet? Possible valve issue?

 

[grandpa Love]

Haven't checked compression yet. Did
pour atf in carb, smoked, revved way
up,back fired a lot and started running
worse. Never did smooth back out. Not
the usual results......

 

[cleddy]

Them diagrams look pretty straight forward. Back in the day, about 50-60 years ago my Dad replaced Carburators and thru the old ones in the scrap iron pile. Wondering if they can be rebuilt?? They are not broken-most likely need floats if water got in them.Cleddy

 

[grandpa Love]

I would dig them out of that scrap pile!

 

[cleddy]

I did and decided yesterday maybe I should look into them(2) They are Marval-scribner & Zenith and replacement cost a bunch if you can find them?? Cleddy

 

[RogerinIowa]

Try a different manifold. They can fail inside causing exhaust and intake to mix. Had a new one that was defective.

 

[kossuth]

Aside from a manifold leak I'd wager on a there being an issue with the carb. Does it have any Marvel Schebler markings/stampings/tags on it or is it completely minus? Might be that it still has junk/crud in the passages. I've had pretty good success using an ultrasonic cleaner knocking that real tough crud out the carbs I've rebuilt. Torch cleaner tips are helpful too. If it's the OE carb I would dunk it in a ultrasonic cleaner with a 50/50 solution of water and cleaning vinegar and running it for hour with heat. Vinegar will break down any rust in any of the passages.

 

[Eman85]

Torch cleaners are nice but find a friend that plays guitar and get their old strings. You get a nice assortment of sizes.

 

[old]

Probably missed something in the carb or a manifold leak. Worked on a 9N yesterday with a problem a lot like that one

 

[HarryVanderpool]

When all else checks out fine, inspect inlet and exhaust pipes for blockage.
Sometimes rodents will fill exhaust with bedding that later swells and clogs the pipe.

 

[Mad Farmer]

I had an exhaust leak years ago, and did carb same time I did manifold. Local garage still has the nasty ZEP carb cleaner dunk tank, that stuff loosens up everything. I used a good complete quality carb kit and all has been well with carby since then.

I did crack that manifold plowing snow when the muffler got bashed on a snowbank and the exhaust flange broke.

Beware the new Chi-Com manifolds. Some won't fit. First one I tried was cast in a poor shape and would not allow the throttle/governor linkage to work, even after a 1/2 hour taking an angle grinder to it. The next one I got from a different source fit perfect.

 

[old]

Not likely to be the problem but never hurts to check. Point gap correct at 0.015??

 

[John in Mich]

A long time contributor to Ford tractor pages often said, many carb issues are spark. His handle was Sparkymiester. A week spark requires more fuel. I would look at everything contributing to (or restricting) spark. Points good, properly timed? Spark plug wires good copper or did someone put automotive wires on? etc.

 

[Maineman]

Id look at weak spark.
Dirty points

Joe

 

[JMOR]

Look for the LED sticking thru hole in wall.