Welded and now it won't start.

[Mundy]

I had to weld something on a snowmobile trailer today. I hooked to it with the tractor and pulled it into the barn. Did my welding and went to start the tractor and I have no power.
It never crossed my mind to disconnect the trailer.

This is a 1981 Mitsubishi with very simple wiring. Alternator/voltage reg/ starter/glow plug
1. I checked main fuse and it is fine. I even swapped it just in case.
2. I still have head lights and the temp light on the dash but the gen and oil light no longer light up with the key on.
3. there is no click or anything when the key is turned.

Does anyone have any sugestion of where to start looking?

 

[carpenter383]

Yup it's not a good idea to weld on a machine without unhooking the batt.
Have you checked for voltage at the starter solenoid?
Are there and saftey switches that could keep the starter from cranking?
You might check for a fuseible link somewhere in the starter solenoid wiring.

 

[mustangsallysdad]

Yup it's not a good idea to weld on a machine without unhooking the batt.
Have you checked for voltage at the starter solenoid?
Are there and saftey switches that could keep the starter from cranking?
You might check for a fuseible link somewhere in the starter solenoid wiring.

Yeah...sounds like a fusible link or a diode.

 

[captaincrab55]

Yeah...sounds like a fusible link or a diode.

Wouldn't a diode be a charging issue instead of a starting problem???

 

[banjodunn]

G'day if you have got lights etc then i do not think you have got a fuse prob it sounds to me like you have got a safety switch or possiby an ign switch failure and i think that this woud be purely coincidence to the welding. If you had a late model computer driven machine then i would suggest that you disconnect battery or fit an anti zap unit when welding however many times i have welded to machines and i am yet to have a prob maybe i am just lucky but i do take care of where i position the earth ( sorry ground for you over there) and i make sure i have it as close to the wed as possibe and make sure it is cean. Getting back to your prob i would look for probs as i said earlier you would be very very unlucky to have caused the prob through welding


Jon

 

[captaincrab55]

Mundy, Does your Tractor use a relay in the safety circuit???

 

[mustangsallysdad]

Wouldn't a diode be a charging issue instead of a starting problem???

Regarding a diode being a charging vs. a starting issue...Not necessarily...if it can't start, it can't charge. The corellation being that there is most often a diode in series with the starter motor, starter relay, a slow blow fuse (fusible link), fuse box and the assorted safety relays. A low-impedance short in the diode could be caused by "current bunching" from welding backfeed. Doesn't take much current (ma)to melt the silicon in a diode.

 

[captaincrab55]

Regarding a diode being a charging vs. a starting issue...Not necessarily...if it can't start, it can't charge. The corellation being that there is most often a diode in series with the starter motor, starter relay, a slow blow fuse (fusible link), fuse box and the assorted safety relays. A low-impedance short in the diode could be caused by "current bunching" from welding backfeed. Doesn't take much current (ma)to melt the silicon in a diode.

Tell me more about a diode in series with the starter motor.. I'm in a learning mode today....

 

[mustangsallysdad]

Tell me more about a diode in series with the starter motor.. I'm in a learning mode today....

I realized he has a 1981 model tractor and from the sound of it non-transistorized ignition and probably mechanical safety linkages as opposed to electrical safety relays...so I doubt there are any diodes other than perhaps in the alternator...his problem is probably a lot simpler than I was thinking...there's usually a blocking diode between the safety relay circuits or seat switch and the starter relay on the newer tractors.

 

[deepNdirt]

remove and clean both ends of both the ground Battery & frame and pos+connections at the starter as well as the battery, what might have already been a weak connection may have gotten worse when the welders ground found its way through the tractors ground system, the grounds are as equally important as the Positive lead connection, in fact I've found that in most cases of troubleshooting a starting issue 80% of the time it winds up being a bad ground,
good luck!