JD Tractor 770 - Engine Stalling Need HELP!!

Rainman5150 · May 16, 2015

Hello Everyone, Hope Y'alls day is going better than mine here.

I have a JD 770 That was running great for years. But now its not. Whenever it is either under load or even just going up a small hill it just bogs down and if I dont stop and drop it back into N it will stall out and die. When I do put it back into N it takes a min or so to get rpm's back up but as soon as I put it back in gear and try to move it bogs down again. Now I'm not the only driver of this tractor. We rent out some barn stalls to some folks for their horses and they do use it to clean out their horses mess. I think they might have ran the fuel dry and never primed it or did it wrong.And their out of town so I cant ask them. But I also believe this unit is self-priming, Is that correct or I'm wrong here Or is their another issue all together

I've checked all fluids and they seem good and checked and blew out the air filter and it seemed to do better for half a day but then back to having issues but I could be wrong about since I wasn't putting it under a load or going up hills, just mowing our field. If anyone could please help that would be outstanding. We have another storm coming in and we we need it to fix some flooding issues.

Thank You

beenthere · May 16, 2015

:welcome: to TBN

First blush, if you are in immediate need of a tractor, then best try to get it to your Deere dealer. Or find a tractor for a replacement at least in the short term.

Another thing to ask, is how are you mechanically for getting your own service technical manual for this model and taking the time to chase down what is wrong?

Others here likely will be able to start you on a search and fix mission, but off-hand I don't know where to start you off.
I will look in the copy of the tech manual that I have that covers the 770. If I can pinpoint what you describe as a problem they list in the trouble-shooting, I will let you know.

Did you drain the water from the fuel sediment bowl?

Also, what long-term maintenance do you do with this tractor on a regular basis?

zzvyb6 · May 16, 2015

770 is 3 cyl Diesel. Correct ? Ist guess is that some dirty fuel was put into it and there is a filter in there that is flow rate limited because of water, muck, or some other stuff. On mine there are two filters: one at the base of the tank and one at the motor. There is a fuel shutoff valve in the line too. It could have been partially turned (as in 'OFF') and that also is limiting the fuel supply.

Look around for water in the separator as mentioned. From the sound of it, you can run on the secondary filter bowl of fuel (the one in the motor compartment) until it gets low. Then the motor bogs.

Neither a Borrower nor a Lender be, they say. Now you know why.

Rainman5150 · May 16, 2015

@beenthere

Thanks for replying, The closest JD dealer is over a hundred miles away so...yea. I have my skidSteer, that my brother borrowed on its way back now so hopefully with a little luck and fast hard work we should be good. Of course its not here when we need it most...lol

I have looked briefly online for both the operators and repair manuals but already knowing how much of a headache it can be finding JD info could be when I searched for something on my Gator, I really didn't look to hard I figured come here and try a post first, Hoping maybe there is a common fix or something that I might be overlooking since my mind is more focused on my drain repair right now. And once I can get my Skid home and this drain dug and pipe moved into place, I'll have more time than I know what to do with to start working on the tractor. Except when you don't have all your equipment (Toys) home and at your disposal and your in high need of them, time goes pretty slow way up here in the mountains..

But back to getting the manuals that I need, I know where to go to buy them online but I'm a former IT Tech and Web Designer so I know how to search and work the internet to get what I need or want for free or at least a reasonable cost.

As for draining the bowl, no I haven't yet but I did think of that and was going to but as of now no not yet. And for long Term maintenance, I guess the usuall standard that needs to be done. With the tractor, to be honest this is the first issue I've had with it since we got it about two years ago. It came with the house and property when we bought this place. Don't know for sure what previous owner did but I don't think he used it much since it only had a couple hundred hours on it when we got it.

Rainman5150 · May 16, 2015

@zzvyb6

Thats exactly what I was thinking that these folks did. Either ran it dry or used cheap fuel or both. I did look at the shut off and its in the correct position it needs to be, but it is tight as in I could not turn it by hand to the Off position, that I would need to use pliers or something.

And yes that is a lesson I've already learned way to many times and when the use of the tractor was put into the lease of the horse stalls I was in Afghanistan so I wasn't here to put my two cents in on that.

beenthere · May 16, 2015

Then sounds like you have not let the water out of the separator since you have owned it. That would be a good place to start and then get the fuel flowing good from the tank. If the fuel is gunked up with algae or crud, it should become evident at this time. Report back... and will go from there.

But order the service tech manual from Deere, or get one from eBay. Being that far from a Deere dealer, you need to have this manual for quick reference and to keep your tractor running. Or get it from the web.. as you suggest.
I won't keep the CD in the computer waiting any longer.

JimRB · May 16, 2015

I have an 870. On my tractor there is a water separator under the fuel tank with a filter. Up from by the fuel pump/distributor is another filter. That one up front seems to get gunked up more than the one in the back. When the front one is gunked up the tractor may start but no power.

I buy two when I buy a filter so I have a spare.

Fawken · May 16, 2015

Sounds like air in the fuel lines. Open the petcock nearest the pump (if it has one) and get all the air out.

zzvyb6 · May 17, 2015

Air in the lines (as in they ran it out of fuel) would make the motor run very rough and stay at low rpm until the pump catches up and the air passed through. If the initial rpm can go to max, the problem is not air in the injector lines. It will also puff black smoke when restarting after a fuel runout. Loss of power and rpm after a normal start is a fuel delivery problem. Most likely dirty or contaminated diesel oil has plugged one of the filters. Clean the bowl and the screen with an air hose.