Farmall 400 dies after 30 seconds, fuel or electrical issue?

pmarkel · Mar 15, 2018

What we have here is a Farmall 400, 12v negative ground with pertronix ignition and hot coil, one wire alternator. Started right up today, made it out to the yard and died there after about a minute. I measured the battery and it was down to about 12.6 but still turned the engine over enough to start again. Ran for about 30 seconds and I measured the battery terminals to confirm that it was charging about 14 volts. Same thing, little hiccup and dead. Twice more it did the same thing: started ran and idled well and cut out after 30 seconds. On the final attempt to turn it over, the battery sounded weak so I turned the key back to off but it kept weakly cranking anyhow until it ran down the battery. I went to put a charger on it but the charger wouldn't accept the battery while hooked up to tractor (which this charger always has before). So I popped the battery out and put a spare in, connected the positive terminal but couldn't ground it because the negative terminal would spark and smoke awful on each contact of the grounding strap which to me indicates a short circuit somewhere in the wiring. I did check the fuel supply at the carb and gas runs through the line freely so I don't think it is a matter of fuel delivery. Could my ignition switch have failed and created an open or shorted circuit? Thanks,

Pete

tractorsam · Mar 15, 2018

It sounds to me like on your final attempt to start it
the contacts in the starter solenoid welded
themselves together (hence the continued
cranking). This is probably why the charger wouldn't
charge the battery while hooked to the tractor and
why attempting to hook up another battery is
causing lots of arcing. Try disconnecting the starter
solenoid and you'll probably be able to hook up the
new battery. Tapping the solenoid may cause it to
release. As to your original issue, try checking for
spark when it quits or try immediately restarting - if it
won't restart immediately but will after sitting a little I
would suspect a fuel restriction. Good luck. Sam

old · Mar 15, 2018

Starter solenoid has welded it self up due to low battery power which causes a lot of. Tapping on the solenoid some times free them up heat.

Till you have that fixed hard to do any real trouble shooting other then testing gas flow which need to be enough to fil la pint jar from the carb drain plug in under 3 minutes.

John T · Mar 16, 2018

I saw that happen fairly often usually in cold weather with a weak battery because the starter solenoid stuck/welded close. Even if you might shock it loose once those contacts get all burned and carboned and pitted they aren't ever as good.

12.6 volts is typical for a fully charged battery and while charging subject to load and charging system it may rise from 13 to 14+

I don't know now from here if you have an elec ignition problem, get the solenoid and battery problem resolved n see what happens

John T

pmarkel · Mar 16, 2018

(quoted from post at 05:26:55 03/16/18) put a charger battery in and tapped the solenoid. Fired up fine and ran for 5 minutes then died. I checked and there was gas in the bowl but there was no spark when I tried to get it started again. It started a couple more times over half an hour of trying to get it in the shed. I checked and with the key turned you get 12+ volts to the positive side of the coil and .95 volts to the negative side. Any chance I could have a worn distributor leaking voltage? Thanks,

Pete

John T · Mar 16, 2018

"but there was no spark when I tried to get it started again."

That's an elec ignition module problem,,,,,,,,,,,or coil problem,,,,,,,,,,,,or ballast problem if it has one,,,,,,,,,,, or ignition primary circuit problem from battery to and through ign switch down to your coil. It could be a dist cap or rotor problem depending on where you found no spark. If the coil is producing good spark but NOT any of the plugs then its a cap or rotor problem. I have seen after market high voltage ignition systems (when running wide plug gaps) cause cap or rotor arcing failures

"I checked and with the key turned you get 12+ volts to the positive side of the coil and .95 volts to the negative side."

When the elec switch is closed, as it usually is unless a piston is at TDC ready to fire, I would expect battery voltage on the coils high input, but near zero volts on its output as a closed switch or points takes that to ground

" Any chance I could have a worn distributor leaking voltage?"

I kinda doubt that, when points or an elec switch is closed that allows the coil to conduct current to ground. Then when points or switch opens the coil fires.

You may have an elec switch that's failing if its NOT a bad coil. Or else maybe a simple wiring problem. Maybe try to hot wire direct to the coils input by passing the ign switch n see if she fires then.

A test lamp on the coils output to dist terminal should flash ON (switch open) and OFF (switch closed) as the engine is slowly cranked over............

Some elc ignition systems still use an external series voltage dropping ballast resistor, if you have that the resistor or its wiring could have a problem.

John T

old · Mar 16, 2018

Sounds like your electronic ignition is fried. Electronic ignition tend to be very picky as to volts etc. and are easy to fry

pmarkel · Mar 16, 2018

(quoted from post at 10:40:13 03/16/18)
Charged the battery up again and test spark at the coil. Looked good so I pulled one of the plug wires and checked again. Sure enough nice spark. Started her up and again she ran for half a minute again and quit so I took out the plug at bottom of carb and there was hardly any gas. So I checked the line to the carb again...plenty of gas coming through the line. Put the line back but still a bare trickle coming out the plug hole. Tapped the carb and the trickle became more steady. Decided to pull the bottom of the carb to see if the needle or float was sticking. Moved it up and down by hand with line open to check that gas would flow with the float let down and it does. Blew out the passages in the carb for good measure and all had plenty of air in and out. Put it back on the tractor and fired her up ran for 5 or 10 minutes till she was out of the shed and quit. Tapped the carb again and fired her up and backed her in, then she quit again. My suspicion is the float or needle is sticking. Thoughts?

wolfman · Mar 16, 2018

I know you said that you checked for fuel flow, but it really sounds like the vent hole in the gas cap is clogged. Did you check for fuel flow with the cap on tight or ajar?

pmarkel · Mar 16, 2018

To be honest I didn't consider the possibility of vapor lock so I have been checking with the cap on. That being said, all the caps on that tractor are old, worn, and I should say hardly tight even when on but it is certainly something I would be interested in testing. Unfortunately, the last time I attempted to crank it the starter went. I had the starter over to a guy who does them earlier in the month when it was giving me problems and he said the keyway was worn bad. At that point the tractor wasn't running so he didn't want me to unnecessarily pour money into it until I knew the engine was okay. Therefore he patched it up the best he could. Well that patch finally went.

old · Mar 17, 2018

Does the float needle have a ring for a spring on it and is there a spring on it?? If no spring on it you may need to get a carb kit and go threw the carb real good.

rustyfarmall · Mar 17, 2018

(quoted from post at 17:49:25 03/16/18) To be honest I didn't consider the possibility of vapor lock so I have been checking with the cap on. That being said, all the caps on that tractor are old, worn, and I should say hardly tight even when on but it is certainly something I would be interested in testing. Unfortunately, the last time I attempted to crank it the starter went. I had the starter over to a guy who does them earlier in the month when it was giving me problems and he said the keyway was worn bad. At that point the tractor wasn't running so he didn't want me to unnecessarily pour money into it until I knew the engine was okay. Therefore he patched it up the best he could. Well that patch finally went.

An updraft carburetor that is gravity fed cannot vapor lock, but if the fuel cap vent is plugged, then no air can get in to replace the fuel that is going out, and a vacuum is created. If air cannot get in, fuel cannot get out.

Farmall 400 dies after 30 seconds, fuel or electrical issue?

pmarkel

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