Problem w/ JD 790 compact starting

[Va Mike]

I borrowed my brothers JD 790 to do some landscape work around my place.
I have been using it for 2 days no issues. Today I am traveling across the yard and catch a bump,,,, the tractor shut off, I thought it was the switch on the seat......

Then I noticed I had no dash lights.
After further investigating I found the negative terminal on the battery had rotted and fell off. I cleaned up the battery, put on new terminals.

The tractor will crank fine but will not start.
It is a diesel, it has plenty of fuel. I checked all the connections under the hood I could find.

It won't even sputter .......... Any insight would be greatly appreciated

Thanks
Mike

 

[TedLaRue]

Did you check the fuses? Remember, even with the cable disconnected from the negative side of the battery, the charging circuit is still active.

If the fuses (and fusible links, if any) are ok, then I'd check for voltage at the injectors and work back from there.

 

[TedLaRue]

Mike,

I've thought about your problem more, and would like to add this to clarify my previous post.
The voltage regulator senses the battery voltage to control what current/voltage the alternator produces (the regulator does this by adjusting current through the field coil of the alternator). When your cable fell off, the battery was essentially out of the loop. The battery can suck up some current or provide some current when the voltage at it's positive terminal fluctuates. It behaves like a damper. Without the battery, your regulator may have momentarily allowed an over-voltage, hopefully blowing a fuse.

If no fuse is blown, then the question is whether there is fuel to the injectors, and whether the injectors are firing.

Your 790 has a fuel shutoff relay which controls a fuel shutoff valve, for what that's worth.

Did you go through the priming procedure (even though you didn't run out of fuel) ?

I have the JD service manual for your machine. The electrical schematic is very complete, except that it shows nothing about the fuel injector circuit.

Keep us posted...

 

[Willl]

voltage at the injectors

Huh ??????

 

[TedLaRue]

voltage at the injectors

Huh ??????

Umm....yeah, Willl, that doesn't make any sense, does it? I guess I was determined to find an electrical problem and got confused thinking about cars with electronic fuel injection. Duhh...

Sorry for the misinformation.

Instead Mike should check to be sure there's voltage at the fuel shutoff solenoid (on the right side of the engine, with an accordian-style rubber boot protecting the shaft which should move when the solenoid is energized).

 

[Va Mike]

Thank you for the info.
I was able to get a hold of a JD dealer the next morning and he suggested the fuse also. My problem with that info was I had no idea where the fuses were located. The dealer looked thru the manual told me where to look and sure enough the fuel soleniod fuse was blown.
Replaced the fuse, turned the key and back to work.

Thanks for the help
Mike