Farmall F-12 starting pain

I have a 1937 gas F-12 that has me stumped! It is rebuilt top to bottom. Before I painted it it would start sometimes with the hand crank. Now, it might start with the crank 1 time out of 10, but if I pull it it starts in 3 feet! What should I be looking at? Mag has new coil, points, and condenser, bit me once already, and a rebuilt fuel pump and carb. I did use the old throttle shaft in the carb because the new one didn"t fit quite right. The fuel pumps because as I crank it agitates the dirt in the fuel bowl. Most times I try to start it I can smell gas so I assume it"s getting plenty. All I know is it is going to a show on Friday and I can"t get it to run by itself!

Does impulse on mag work. Bernie Steffen

check your timing and make sure you have oil in the aircleaner. pg

If youre smelling gas, your choking it way too much, or you float is set way too high. I fought my 14 for 5 years before I could get it hand crank. I only choke it through 2 clicks of the mag, then unchoke it and 9 times out of 10 she fires right up. Friend of mines 14 is the same way, too much choke and she wont fire.

Oil in the aircleaner wont make it start better! Hoss

I have haad the same problems on my fleet of f-12/14s. They ususally boil down to the following problems.

1.) If you removed the magnet off of the magneto you need to put a keeper (a bar of steel) accross the ends of the horseshoe magnet or you will loose the magnetic charge. I generally find that after every magneto service or using magnetos that I do not know when the magnet has been charged, I will charge the magnet. That will give me good hot spark continuously. You may get hot spark turning over the magneto but to have continuous hot spark is what you want. Pull starting will give that for you if the magnet is weak.

2). Check the inpusle coupler to make sure it snaps freely. You need this for hot spark.

3). Check leak down on the fuel line and carb. I generally have the fuel line bent slightly down hill to the carb so that fuel says in the line and doesn not leak back. Also check to see if the carb is leaking into the manifold and draining itself out.

4). What condiditon is the fuel pump in? Does it allow the fuel to leak back? The pump will pump and fill up the fuel lines in three feet when pull starting.

5). Check the float level to make sure that there is the correct amount of fuel for the carb to work correctly.

If the carb float, fuel pump, magneto, and the impulse is set right, you should be able to start the f-12 with a quarter turn. I have had tractors sit for weeks to start on the second crank.

Good Luck!

I have had the exact same problems. What I found is the air/fuel mixture screw needs to be set at 1 1/2 turns out from bottom and the idle fuel screw needs to be at 3/4 turns out from bottom. This will at least get you started. Some fine tuning will be required to get it to run right.

Dirt in the fuel bowl? You should clean the dirt out of the sediment bowl. Is your carburetor adjusted correctly? Are you choking it too much when you start it? It should not smell gas while you are cranking it unless it is flooding. Make sure that the float level is correctly set and that the needle and seat are not sticking.

Now this is funny...

Funny not in the fact in won't start easily for you...funny in that what you describe is precisely what my brother experienced with his.

Doubly frustrating for him is that he is VERY experienced with the F series mags, but the F-12 drove him to utter madness. Could NOT find out what in the heck was going on.

One day on a gut hunch, he poked around in the mag of the F-12 for the twenntieth time and found a wire that was shorting out against the inside of the mag housing. Sometimes it would, sometimes it would not short.

I don't have the precise details of what he found, but more information can come from him if you'd like.

Case closed on this problem.

pgo knows what he is talking about. While I have an F-14 that will start with the intake tube off I have an F-12 that will not start hard the same way. A restorer of reknown ability, his tractors have been in numerous publications and calenders, mentioned to try putting 30 weight oil in the aircleaner and give it a whirl and yes, it started right up. Seems the intake having some ristriction is vital to getting gas into that updraft on some 12/14s evidently, more than others. If you've rebuilt an F-12/14 carburator you know how simple they are. The oil in the air cleaner thing is something you'll definatley want to try in eliminating things keeping your 12/14 from starting or running well. By the way the restorer was a fellow we know as pgo!

The impulse works. I can smell gas without choking it. I never knew about the magnet loosing it's charge thing until now, heck, I've had it off 4-5 times in the last 2 weeks! I am going to try resetting the carb and try it again. Yesterday was the second time I has tried to start it with a totally fresh mag and I still has to pull it. I walked up to it after supper, gave it 4 pulls, and she was off and running! I rebuilt the engine several years ago and it has sat in my shop since last July(2007) awaiting me to install thew heisler overdrive and paint it, which I did a month ago. Attached is a picture! Those Maple-Hunter cut decals sure look nice!

I have a slightly leaky needle valve in my 12 that will cause it to start hard if it has a full tank of gas. If I run with a half tank of gas it starts fine usually within 4 pulls. The top of the tank is just high enough to gravity feed fuel to the carb.

Well, got mad today and swapped out the magneto magnets for one that I knew was good, 2 pulls and she's up and running!!!!!!! What a nightmare! I guess I can push the magneto charger project up.

I understand the "nightmare" thing, I didn't talk to my F-12 for months!

Right now I'm so mad at it I just might make it sit in the corner for another 9 months to think about what it's problem is!