400b won't stay running

Chuckk · May 29, 2017

Hello!

I have a Case 400b that ran like a champ up until a week ago. I plowed a 2 acre field and parked in when I was finished. I always let it idle for a few minutes before I shut it down and there weren’t any signs of trouble. Came back 2 days later, started it, drove about 20 yards, and then it quit. Crank it over, it will start, run for 2-15 seconds, and then quit. Can’t even get it to run on ether. It acts as if it is starved for gas and sometimes dies like you hit the kill switch. Open drain plug on carb and gas flow is good. Spark was ok but weaker than I would like, however it shouldn’t have caused this issue. Compression was 117,125,127,130psi.

I have since then rebuilt the carb (Was squeaky clean before rebuild), new plugs, new coil, new points and condensers, and cleaned the distributor cap.

Still no luck. Will start after cranking a few seconds, run for 2-15 seconds, and then die. Once I did get it to run for about 5 minutes then it died.

Anyone have any ideas what could be causing this? My next step is to redo the wiring hoping to find a hidden short somewhere.

Any help is always appreciated.
Thanks!
Chuck

old · May 29, 2017

#1 make sure you have a good blue/white spark that will jump a 1/4 inch gap or more on all the plug wires and the center wire of the distributor cap.
#2 check the point gap and make sure it is correct on all the cams.
#3 try a hot wire from the battery to the ignition side of the coil and if it runs that way like it should then you have a bad wire or switch.
#4 pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in less then 3 minutes and yes catch the gas to look for water/dirt etc.
#5 when was the last time you serviced the air cleaner and dumped the water and mud out of it

oldproudvet · May 29, 2017

Weak spark will mimic fuel problems every time. Remember: carburetor is a French word meaning "leave me alone"

Tubacase47 · May 29, 2017

Check the screen in your sediment bowl; I had a CC which had the same symptoms and the screen was plugged.

olgentdc · May 29, 2017

mite be the condensor ,, if it stalls turnoff the gas immediately , then open the carb bowl and chek if it is pratically
empty. there is plenty gas still in the carb at shutdown , then it miore than likely is a spark issue ,.

Chuckk · May 30, 2017

Thanks for the help!

At this point I'm positive it is not a fuel problem. Flow is excellent and plugs are wet if it doesn't start.

Oldproudvet, I am in 100% agreement with you on the carb, I prefer to leave them alone. :lol: Only reason I took it apart was I thought maybe water was clogging one of the jets. Sediment bowl had a few beads of water that may have made it's way to the carb. The bowl gasket also had a vary small leak. Since I had it apart mine as well rebuild it. Also completely drained gas tank, dried it, and put fresh gas in.

Old, #1-2-4-5 are not a problem. Next time I'm home I'll try #3.

The points are gapped properly. It is a new condenser but I guess I could have received a bad one?? I ordered a electronic ignition kit to do away with the points and condenser.

Ill update in a few days. Thanks!!

Chuck

mEl · May 30, 2017

A couple weeks ago I did a tuneup on a 530, ran well for a couple hours and quit, would start but not rev up, pop n carry on, put old condenser back in and works fine.

Chuckk · Jun 11, 2017

Today I finally got a chance to work on the tractor.... And I discovered I'm an idiot.. after $80 in parts, pulling my hair out, I decided to trace all the wires one last time before I replace them.

Taced + wire from battery to switch, then to resistor, then to coil, then it hit me; why is the wire running from the resistor to the + side of the coil and the - side going to the ignition?

Yup, in my haste and history of working mostly with +ground tractors I wired the coil backwards.

30 seconds later, switch wires, hit the key, bam it runs!!! And just in time for hay season!

Big thank you to everyone for their advice and I hope future readers can learn from my mistake.

Thanks!
Chuck

400b won't stay running

Chuckk

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old

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oldproudvet

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Tubacase47

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olgentdc

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Chuckk

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mEl

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Chuckk

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