Only runs with key in start position

   / Only runs with key in start position #1  
B

bigDOJ

New member
Joined
Mar 16, 2021
Messages
3
Tractor
Mitsubishi 180 D
Was running good, then started dying often, and now will only run when the key is in start position. Any Ideas??
 
   / Only runs with key in start position #2  
Weak "hold" position on fuel solenoid?
 
   / Only runs with key in start position #3  
Check your grounding.
 
   / Only runs with key in start position #4  
If the starter turns over and the engine fires the fuel solenoid is as grounded as can be.

I suggest there's a faulty ignition switch from wear or corrosion.

btw, starter solenoids have pull and hold coils but few other do. The fuel solenoid is so much smaller and requires far less current to hold it. It likely doesn't use a relay either.

The fuel solenoid may be more like a diverter valve solenoid that draws a few amps vs a starter that takes nearly all a battery has.
 
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   / Only runs with key in start position #5  
the old grind said:
If the starter turns over and the engine fires the fuel solenoid is as grounded as can be.

I suggest there's a faulty ignition switch from wear or corrosion.

btw, starter solenoids have pull and hold coils but few other do. The fuel solenoid is so much smaller and requires far less current to hold it. It likely doesn't use a relay either.

The fuel solenoid may be more like a diverter valve solenoid that draws a few amps vs a starter that takes nearly all a battery has.
Click to expand...
That is not always correct, the starter uses a different ground path than the rest of the system.
 
   / Only runs with key in start position #6  
The starter and fuel solenoid are grounded through the engine block. If they both work in the key start position they are grounded ok. Neither has a ground wire/connection to fail except the main ground to the engine. (wouldn't crank over)

A bad key switch might not send power to the solenoid in the run position I've replaced two ign switches and problems ceased. One was in '98 and one was in a '04. Both had spent plenty of time parked outdoors, but I suspect contact wear due to age & hours.
 
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   / Only runs with key in start position
  • Thread Starter
#8  
the old grind said:
The starter and fuel solenoid are grounded through the engine block. If they both work in the key start position they are grounded ok. Neither has a ground wire/connection to fail except the main ground to the engine. (wouldn't crank over)

A bad key switch might not send power to the solenoid in the run position I've replaced two ign switches and problems ceased. One was in '98 and one was in a '04. Both had spent plenty of time parked outdoors, but I suspect contact wear due to age & hours.
Click to expand...
My original thought was a faulty key switch, that I replaced, after determining that it was not a fuel problem. The new switch did not solve the problem. Do you think it could be a bad solenoid or something else?? I am not very educated on these mechanical issues, so all of your help (in laymen's terms) is deeply appreciated. Thank you very much
 
   / Only runs with key in start position #10  
I had a similar problem on a borrowed B21.
Naturally I was far from my shop.
Could start and move as long as I left key in start.
OK, did that enough to clear the road and did trouble shooting.
After poking around I discovered a blown 40 amp fuse.
Naturally no spares so I pried it open and forced the fusable wire to make contact.
WORKED so I limped home., bought and installed new fuse.

Why is it troubles always show up when far away and no tools.
 
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