Help Starting 1950 B

[Dean Lydey]

I've got a John Deere 1950 B that's been a fairly reliable tractor. I had the mag rebuilt 2 years ago and runs fairly well. It doesn't like to start after it's warm, but oh well. Last weekend I could not get this rascal to start even after I tried some of the standard "extra measures" that I sometimes need to take. What I mean by this is when I have difficulty, usually a new pair of D21 plugs brings the tractor to life. It didn't help this time. I'm thinking that if I have fuel and spark I should be in business. I do seem to have fuel..maybe even too much. While choking the tractor and repeatedly trying to start it, I do get fuel to drip from the open petcocks. This amounts to drops, not ounces. My question is how can I confirm I've got spark to the plugs? What is the specific procedure where the plug is removed and you watch the gap for the spark? I'm thinking the plug needs to be grounded in some way but I'm not sure. As I said, I had the mag rebuilt recently, maybe the plug wires? Please advice this novice.

Thanks in advance.
Dean

 

[Anonymous-0]

The fact that you say it won't start when it's warm would have me worried ...

 

[Dean Lydey]

It has always done this since I've owned it for 4 years. Is this a symptom of something that's now gotten worse and is now preventing it from starting at all? What might this be?

 

[CLW]

Dean, you should be able to lay or hold the plug against the frame and see the spark jump. You can get a test plug at a parts store that has a clip on it that you can clip it to frame. They work on any gas engine and you don't have to worry about it having a good enough ground or not.

 

[Matt Mckay]

take the spark plugs out and roll the tractor over. look at the gap and that is how you will tell if you have spark. *MAKE SURE THAT YOUR SPARK PLUG WIRES ARE COVERED WITH RUBBER WHERE YOU ARE HOLDING THEM OR YOU WILL GET A GOOD LITTLE KICK. you can also check the points and condensor. i had a A that when it got warm it did not want to run, it was the condensor. this should be a simple fix.

 

[Dean Lydey]

Thanks for the advice. With the mag rebuild I got new points and condenser. My intent with the rebuild of the mag was to help this hot starting issue and it didn't seem to help.

 

[Anonymous-0]

Check spark , compression , and if they are good it's most likely a fuel problem . These old carbs on these tractors are notorious for giving people problems .

 

[John T]

Dean, a way to tell if you have spark at the plugs is to remove them and have their wires attached (but not shorted to tractor) and have the sides of the plug against tractor steel (so sides are grounded) and crank her over n see if they fire??????

If the plugs are bad you can do the same just using the plug wires ONLY by having their ends within 3/16 inch from tractor steel and crank her over n see if she fires????

If the mag is good there ought to be a good visible BLUE spark NOT a faint thin wimpy yellow one.

When cranking for a mag to produce spark she needs to have a lond sharp distinct SNAP each time the impulse trips and NOT a faint dull clunk. What mag you have and is it impulsing???? cuz if not she cant start although she could still start n run fine if pull started.

Often on mags the cause of non firing is burned or bad points or they are mis gapped. Check the gap and if they look good but only gray oxide coated, run a dollar bill between then and clean/buff/polish them n try again. if badly burned or pitted repalce them. Id uee wire core wires NOT carbon core suppressor plug wires...

Mag troubleshooting is an entire other post n depends on what mag you have so let us know n try the above first n we can go from there.

NOTE You say its a Mag buttttttttttt you sure its NOT a Wico XB battery powered distributor???? cuz if so troubleshooting is different n they DO NOT impulse as mentioned above. However checking the plug or wire firing remains the same PLUS hard hot starting can be caused by a condensor problem or again burned points.

What ignition is it????????

John T

 

[Anonymous-0]

Check spark , compression , and if they are good it's most likely a fuel problem . These old carbs on these tractors are notorious for giving people problems . Fuel would be my guess to your problem .

 

[Mike M]

Be careful when having the plugs out and cranking these tractors over. If you happen to have alot of extra gas in the cylinders (happens alot on old Deeres)then it sprays right out and the dangling wires ignite it then you got a BIG fire going !
I like to pull the wires up out of the way.

Also for the classic case of hard or no start when hot could indicate coil problems. Did they put a NEW coil in ? but sometimes NEW parts are bad too.

 

[johns48jdb]

any time you have trouble starting a warm engine its will always be the coil. i'm surprised that it hasn't just completely quit on you when it gets hot. the local small engine guy has a neat little tester that goes on between the plug and the plug wire. it has a window in it that you can see the fire jumping across two points inside of it to test if the plug is at least getting fire down to it. if your fouling plugs you've got to much gas going to the engine. clean your carb and don't open up the jets but just a very little bit at a time. give the engine time to react to the new carb setting before doing any more adjustments. patients has its rewards here.

 

[jd b puller]

Start by getting rid of the Chumpions. Try a set of AC77 or Autolite"s (can"t remember the #, someone help me out). What starting procedure are you using when hot? (choke, throttle position,etc.)

 

[CalJim]

I have been using Champion plugs all my life, the last couple years on this forum I have seen numerous posts claiming how bad they were, I ignored them all. So I put some Champions in a 36 BN I restored last summer. Was hard to start and did not run as well as it should have on a new rebuild. Put some Autolites in, starts on the first pull consistently, runs like a top. I will never use another Champion. CalJim

 

[Dean Lydey]

I've tried to restart in all kinds of throttle/choke conditions. No luck, never.

 

[Dean Lydey]

I will try Autolite's or AC's

 

[Dean Lydey]

I think you are suggesting the spark tester after the tractor is warmed to confirm spark. That makes good sense. This tractor has no coil, it has a magneto. Is the term condensor interchangeable with coil when you say the no start when hot is always coil?

 

[Mike M]

Magnetos have an internal coil and also a condenser. Either one can act up or even be bad when new.

 

[4020LP]

Put a new coil in the magneto---end of problem. It doesn't matter what else was done to the magneto, what you're describing are the classic symptoms of a bad coil.