790 Sporadic Starting

[sriddle1]

Last couple of weeks noticed this occurring more and more. At one point I reversed the starting key (25 seconds) to get the glow plug going, still didn't start. I check the Fuel Filter, opened the drain and full of fuel. Purchased diesel within the past month, Shell Brand. Changed the Seat Safety Switch last week thinking that was possibly the issue, battery all charged...... For you seasoned mechanics (which I am not) any suggestions or steps to isolate the problem further. THANKS

 

[RobS]

Does it crank and not start, or not crank?

 

[sriddle1]

Does it crank and not start, or not crank?

Rob S, Thanks for the Response...........Thought of that on my drive back home after posting, should have added that data point. YES, it cranks strong in all occasions, sometimes it starts and sometimes not. Thought with winter coming up, removing FEL & installing front-mount snowblower, not a good time to figure this out.....

Just read this thread, I'll look at these things tomorrow.........

http://www.tractorbynet.com/forums/john-deere-owning-operating/206564-jd-790-cranking-but-not.html

 

[dieselcrawler]

Fuel stop solinoid could be going bad, or, as I've found on a similar solinoid on equipment at work, the wiring going to it... I would be willing to bet that the solinoid will rest (unenergized state) in the 'kill' position. It will likely have a dual coil, one to draw it back to the 'run' position (higher amperage, short duty cycle), and another coil to hold it in that position (lower amperage, continuous duty).

If it cranks over good, check there. Simply removing the solinoid will let you test it, but be aware that if the tractor starts, you have no way to stop the motor until the solinoid is reinstalled, and it will likely leak oil from the opening.

 

[CCWKen]

Good argument for the manual cutoffs on the old Ford and Kenbota.
I never have any problem with those. Unless I forget to push it back in.

 

[sixdogs]

Does the 790 have a cold start package? If so, my 5520 acted like that and had a bad sensor on the upper water inlet neck. I did a thread on it.

 

[sriddle1]

Does the 790 have a cold start package?

Sixdogs, My 790 is a 2009 Production Year so I'm unaware of a Cold Starting Package, it has an Ignition Switch position to supply voltage to the Glow Plug + I installed an Engine Block Heater while living in Minnesota @ -35 Winters..........FREEZING! I'm headed outside, cooler temps today mid 80s to go thru the items from the previous thread. I don't remember hearing the Fuel Solenoid "Chattering" as some mentioned, when it didn't start, Let the Troubleshooting Begin..........

 

[sixdogs]

These tractors are bulletproof so don't overthink this. Go with the easiest answers and work up from there. Maybe go see the dealer and ask what he thinks. That's how I found out about my cold start package. I had no idea.

 

[sriddle1]

Re: 790 Sporadic Starting - UPDATE

With notes from the Previous Thread's recommendations I commenced the search.... It started-up right off the bat and I heard the solenoid relay chirping before starting. First, the battery I replaced last year, double checked and terminals clean, connections tight and previously sprayed with the red battery terminal coating. Checked the ground going to the frame to the left of the battery, this tractor has been stored inside since it was new, no rust or corrosion but I still gave it a shot of CRC's Electrical 2-26 Lubricant. Next, Fuse Box... Pretty dirty in there, never have had it open, purchased this used in Oklahoma, still lots of red clay dust around the fuses. Gave it a good cleaning, noticed the "B" Solenoid 3 amp fuse blue'ish tab was almost bleached out clear, pulled it, replaced with spare, sprayed 2-26 over the fuse contacts after cleaning and closed-up. Turned tractor off, fired back-up, checked all the lights, etc. A-OK, and so we'll see in this on-going Easter egg hunt a.k.a. troubleshooting..

 

[sriddle1]

O-BOY, NOT STARTING THIS MORNING...........

Typical, when you need to get something done.....good thing I'm not in the middle of winter w/5 foot driftf, OK count to 5, relax, breathe deeply........ So, I thought changing the Seat Safety Switch the last go-around plus taking the steps I posted would do it, no such luck and the closest dealer is 40 miles away...... Battery all charged-up, Turns-over, I hear the chirping as I turn the key, in neutral, PTO disengaged, no mice eating wires..... and I'm beginning wonder (with no mechanical aptitude, guessing at this point....) could it be the fuel pump. QUESTION: Is there a simple way to tell if it is the FUEL PUMP?