Yanmar diesels on 750 & 790... what caused this??
- Thread starter kebo
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California
Super Star Member
- Joined
- Jan 22, 2004
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- 14,983
- Location
- An hour north of San Francisco
- Tractor
- Yanmar YM240 Yanmar YM186D
I'm going to guess that the fuel circuit on the Yanmar engine in that Deere 750 is near identical to my Yanmar engine in my Yanmar 240. (approximately the same year model). There is no solenoid, no electric fuel pump, no pull cable, or ignition (obviously - it's a diesel).
The throttle lever simply controls how much fuel the injector pump puts out. You pull the throttle down to zero, the pump output is zero, > the engine stops. It's just that simple.
The key is completely unrelated. It controls the starter motor, the manifold heater, and engages or disengages the charging circuit. Turning it off with the engine running has no effect on the diesel engine, aside from the battery is no longer receiving a charge.
Recently I turned the key off and pulled out the key to use the knife that is on my keychain - with the engine still running. When I put the key back in a moment later I forgot to turn the 'ignition' on and ran the rest of the day with it at 'off' position, only discovering my error at the end of the day. The engine never knew the difference. (I've read that doing this might damage the alternator, but it didn't in my case).
The throttle lever simply controls how much fuel the injector pump puts out. You pull the throttle down to zero, the pump output is zero, > the engine stops. It's just that simple.
The key is completely unrelated. It controls the starter motor, the manifold heater, and engages or disengages the charging circuit. Turning it off with the engine running has no effect on the diesel engine, aside from the battery is no longer receiving a charge.
Recently I turned the key off and pulled out the key to use the knife that is on my keychain - with the engine still running. When I put the key back in a moment later I forgot to turn the 'ignition' on and ran the rest of the day with it at 'off' position, only discovering my error at the end of the day. The engine never knew the difference. (I've read that doing this might damage the alternator, but it didn't in my case).
OP
kebo
Elite Member
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- May 16, 2006
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- Lexington, SC
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- 2001 John Deere 790 4x4, bar tires
Yesdeere, read the post by California. I think he got it right, that is exactly the way the John Deere 750's behaved. Removing the key had nothing to do with cutting the engine off, it never has.... the engine will chug right along. The only way to shut those diesel engines off was to completely close off the throttle but sometimes when you did that it still would diesel on. That seemed to be dependent on how hot the engine was. Now the 790 is different, as the other posters pointed out. I was curious about why this was so, and it has been answered. Thanks everyone for your comments!
ScottAR
Veteran Member
California has hit it on the head. The fuel "shutoff" on the 50's is a steel rod that runs from the throttle handle to the pump itself. Shut off throttle and it shuts off the fuel.
The new tractor has an electric switch that shuts the fuel off. Key off= no electric = no fuel.
The new tractor has an electric switch that shuts the fuel off. Key off= no electric = no fuel.