"Brand New" JD 790 needs a little help

Kernopelli · Nov 28, 2008

A buddy of mine at work said his neighbor just picked up a 4-5 year old 790 w/ 3 hrs (actual). Said the older gentleman that originally purchased it brought it home and played with it one afternoon and then just parked it in the barn for about 1500+ days. ( HEY look Ethel! I was wonderin where I parked that thing!!!

)
Anyway, he says the new owner brought it home, checked the fuel (full tank of 4+ yr old diesel) charged the battery and turned the key. It begrudgingly kicked of for a second but now won't restart. The guy at work asks me what could be wrong since he didn't think the diesel would necessarily have gone bad like gasoline can or have caused varnish etc like gas does. He wondered also if the pump might somehow now be compromised or other problems caused after sitting this way for so long?

My advice was that I doubt the pump is hurt. Drain the fuel tank ,pump and lines from injectors back. New fuel filter and fuel, reprime system and see what happens....probably start right up. If it does start, maybe go ahead and change the oil/ new filter just for good measure and enjoy. If it doesn't start up, begin looking from there but I wouldn't recommend hosing it with ether, if tempted, because some small diesels and lots of ether can make for expensive results and lots of crying.

Anyone have any thoughts on what they need to do to get it started? I personally can't imagine that there could be much wrong but the new owner is intimidated about taking any action without consulting others more knowledgeable first ( this is where you come in!).
Darryl

kennyd · Nov 28, 2008

Definitly get that old fuel out of there...It does grow algae after a long time and can gum up the works. And like you said, change ALL fluids and filters soon thereafter.

dirtworksequip · Nov 28, 2008

Just do what you said, Drain the fuel tank and fuel system and change the fuel filter. In fact you may as well change the primary and secondary air cleaners while your at it. Maybe a mouse nest in their after all that time. Since its not broke in yet. I'm not sure what I would do about the motor oil? Break in oil is supposed to be run for the first 50 hours. Try glow plugging before you start it. Under no circumstances ether it to get it started! Good luck and keep us posted as to what happens.

Sincerely, Dirt

Brimstone10x · Nov 28, 2008

I have seen two units that never got broken in .One was a 4610 the other was a 990 (deere) only a few hours on them and sat for a long period after. They both had the racks seized in the injection pumps. On the frist one we disasembled the pump and used a hammer and punch on the rack and got it free after a wile of working it back and forth. we reasmbled the pump and put it back on , re timed it and it ran fine after. The second one we just replaced the pump for about 4000.00$$ Pull the fuel solinod off the pump and the rack ,the thing the solinod pin pushs on should move freely back and forth , if its stuck your friend it up the creek. Good luck to him

WilliamBos · Nov 28, 2008

I would love to find out what happens. Could you keep us posted please??

woodlandfarms · Nov 28, 2008

Not starting meaning? Does it turn over? I would add the battery to your list. I figure a 4 year old battery not having been charged at all is a gonner.

john_bud · Nov 28, 2008

Is the fuel cock turned off?

jb

Kernopelli · Nov 28, 2008

Wow, talk about some fast replies! My thought on the pump was that it probably wasn't seized since they did get the engine to kick off, (stumbling but running for a "little bit") then quit firing and not able to restart.
First, it was fairly cold here when he was attempting to get it started (high teens at night, high 30's during the day), he was supposedly using the glow plugs though. But I would think the combination of OLD fuel, cold temps, tight motor and possible clogged filters may conspire just enough to prevent (re)start up. Plus, who knows how well the "recharged" battery was spinning the motor?
I wont see my co-worker again until Sun or Mon when I go down to his place but will probably get to look at the tractor myself when down there. I'll keep everyone updated as soon as I know more.
I am really curious to hear what he gave for this jewel ($$). It "came with a new 72" finish mower, new (unknown size) tiller and "some other stuff"(???)".

EDIT: "Is the fuel cock turned off?--Good question. There could have been just enough fuel in the line/pump to get initial ignition.

dirtworksequip · Nov 28, 2008

I'd say fresh fuel, filters and a little TLC and you will have it running soon. Remember NO ETHER.

Sincerely, Dirt

john_bud · Nov 28, 2008

Kernopelli said:
EDIT: "Is the fuel cock turned off?--Good question. There could have been just enough fuel in the line/pump to get initial ignition.

Given that it started and ran, even poorly tells me that the pump is ok. It may have black algae in the fuel clogging the filters, water in the lines (very possible) or the main fuel line turned off (most likely of all). Old guys are notorious for following the directions in the manual and you are supposed to turn it off!

Buy some Howes Diesel Treat and add an entire quart to the fuel tank. Top off with fresh fuel (after you determine there is no algae) and put on a new fuel filter. Make sure there are no mouse condo's in the air intake track.

jb

sixdogs · Nov 29, 2008

I had a similar situation and changed the oil using John Deere "break-in " oil. It's in gallon containers. Just ask for it.

I have a 790 and have some thoughts. I suspect the fuel is good enough for now. Look in with a flashlight to see if green with algae. If it looks OK, I would wonder if the fuel system may have lost it's "prime" or has air in the system and needs to be bled.
Thiipossiblity would seem higher on the list than some of the things mentioned so far. It's worth a thought.
It's easy to do but harder to explain. Find an owner's manual for the tractor and follow the instructions.
I've seen tractors sit for far longer in bad climates and eventually start right up and get back to the task at hand. After you get it fully warmed up and used for a couple of hours I woudl change every fluid I could find. Don't forget the anti-freeze.