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Maynard

· Maynard
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6 Posts
Discussion starter · #1 ·
John Deere 455 Diesel. - Been workin on stuff since the 50s. Never done anything this dumb. Battery went out last year. Tried to jump it off with my truck. Wouldn’t start. It would turn over but not start. Went and got a new battery. When I put it in, I found that I had jumped it off with the positive to negative on the battery. I recon I was spinning it backwards.
NOW...battery is correct. Diesel turns over and with throttle on fast appears to run, but very, very rough and with low speed. SO... I turn the switch off and it keeps running. I think that the starter turns it over fast enough to stare a little run away diesilling.
The pump runs and the glow plug gloves.
What yall recon?
 
Yes,most starters will turn the same direction even if the battery is hooked up backwards..some with permanent magnets might spin backwards,but I think the starter drive has a one way clutch that will not engage if it spun backwards even if it has a solenoid to shove the gear into the flywheel ring gear..

As suggested,the reversed polarity may have fried something else--on a diesel there is usually a fuel shut off solenoid unless there is a manual shut off lever on the injector pump..that solenoid cuts off the fuel flow when you turn the key off..if that fails to open with the key on,no fuel will get to the injector pump and it'll just crank over and not start..it may have run temporarily on some fuel still left in the lines and injectors..

Most of the other electrical items on a diesel dont really keep it from running if they fail--the alternator wont affect if it runs or not if it got fried,the battery will just die eventually from it not being recharged..the fuel shutoff solenoid wont open if the battery gets very close to dead to though don't forget..
I'm not a diesel expert but I've been forced to learn basics due to owning two trucks with them..
 
There is a glow plug timer that controls the voltage to the glow plugs but I am not sure that would cause the problem you are describing. It usually means that the glow plugs will not come on or not stay on long enough to do their job. Once a diesel is running, the only thing to alter it is fuel and air. To stop it requires either to be shut off. It is easy to look at the fuel shutoff to see if it is on or off since it only has two positions. Running rough would seem to me to be a fuel issue probably related to the injectors. Good luck with it!
 
Discussion starter · #6 ·
I found it. Thanks to all.
It was the fuel shut off valve. It,would snap back when the switch turned on, then it started to slip back to shutoff position.
Took,some bailing string and tied atoindmthe plunger rod. Good old bungy cord held out back while I did my mowing. Tried to upload photo but couldn’t figure out how.
Anyway, I’ll get one soon. Thanks,again.
 

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Glad you figured it out, and welcome to MTF!
 
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