My 1951 JD B Won't Start

jntpro · Aug 23, 2015

A couple of weeks ago my JD B was running just fine. Then about a week ago when I tried to start it, it wouldn't start. I checked various things, I drained all the gas out (including the carb) and put in new. I cleaned the plugs; they look just fine. I checked for spark and it seemed ok. When it wouldn't start using the starter, I pulled it with my truck and all it would do is backfire occasionally. So I ordered new points, condenser, rotor and mag cap. I just installed them and it still won't start. There is spark at the plugs and gas to the float bowl. The magneto coil resistance checks out good. The mag is tight and has not slipped timing.

Any ideas?

Thanks for your input.

flying belgian · Aug 23, 2015

From your explanation, I'm guessing carb. Sometimes you can take and rap on the carb. with a wooden hammer handle and it will loosen that spec that plugged it.

James Borders · Aug 23, 2015

Take your breather pipe loose at the carb and see if it pops off, if it does you have wasps or dobbers in it.

BushogPapa · Aug 23, 2015

The First BIG mistake is NOT installing New Autolite #3116 plugs...

These JDs can get pretty "Mad" at ya for no apparent reason (personal experience)..!!

Open the Mag and let it dry out (moisture), and/or New Plugs and it sure might like you better...!!

No one here ever mentions the possibillity of moisture inside the Mag, but I can tell you, that was the most common problem with ours if they sat out (in the field) over night...!!

Woke up many a neighbor at 4:AM, trying to start the JD "B" tractors (with straight Pipes)..sometimes had to wait for the Sun to shine on the inside of the Mag Caps to get them to start...

Ron..

JDIH · Aug 23, 2015

I would check the ignition timing (the spark event in relation to the mark on the flywheel). I had a mag that the drive came undone. It still sparked, just not in time

teddy52food · Aug 23, 2015

Did someone switch the wires on it?????

gene bender · Aug 23, 2015

Allthose parts didnt fail just setting there. Didnt you have fire at the plugs before you replaced parts.

FBH44 · Aug 24, 2015

I do NOT know if this would work, but lately every electrical item I have that does not work, I shoot abundant amount of PB Blaster inside, cycle things back and forth, and the thing starts to work, better than every before. I believe that stuff removes corrosion, stops further corrosion, improves conductivity, keeps moistureout. Doin;t know about magnetoes, but I like PB.

jntpro · Aug 24, 2015

I know that Gene, but one thing I didn't say in my description is that we had a lightning strike nearby that did some damage to household electrical components and I thought that the condenser might be degraded somewhat and the points needed filing anyway plus the gasket on the cap was shot. So the bottom line is that I replaced just about all the electrical parts in the mag as a maintenance exercise.

jntpro

jntpro · Aug 24, 2015

No, the wires are in their original positions.

jntpro · Aug 24, 2015

Thanks JDIH, I'll try that and post the results.

jntpro

jntpro · Aug 24, 2015

You are right FBH44. I'll try changing the plugs even thought I sand blasted the plugs that are in the tractor before each try to start it. I know about the "wet mag" issue, I've had that problem several times in the past. But, the tractor has been inside with the mag cap off for about a week while I was waiting for parts and I wiped it out clean before installing the new parts.

Does anyone think that I should have the mag coil high voltage tested? I have spark, but if it's not strong enough under compression , . .

jntpro

jntpro · Aug 24, 2015

Thanks James. I'll try this tonight when I get home as well as some of the other suggestions. I'll let everyone know what the results are.

jntpro

jntpro · Aug 24, 2015

Thanks Belgian, I try this tonight also.

jntpro

jntpro · Aug 25, 2015

I got it running!! Thanks to everyone for their help and suggestions.

In the process of checking the impulse timing, I was watching the #1 plug spark with respect to the flywheel position and noticed that the plug was firing but not in conjunction with the flywheel/cover marks. So I swapped the wires on the magneto and then the spark fell in line with the timing marks. I put everything back together and it started right up! I can't imagine how or why it happened, but apparently someone swapped the mag wires while the tractor was parked outside.

Thanks again for your help.

JNTPRO

Old Scovy · Aug 25, 2015

There is no such thing as a JD 2 cylinder that won't start and run.

rhtx55 · Aug 25, 2015

Always check the lil things FIRST !!
I can remember a co-worker who lost his job after removing about half the wiring from the cab of a new W900.
Rear tail light bulb had shorted, and the filaments had connected and back feeding low filament through the high filament.
Took two of us the better part of two days to re-install the cab harness correctly.
Boss asked me what was wrong with it, you could hear him holler (cussin) for 3 blocks.
Warranty doesn't cover bulbs, and the shop had to eat about 10 hours labor.

My 1951 JD B Won't Start

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