JD Backhoe running at high idle with key off and out

RedDawg

Member
I have a new to me 1988 John Deere 310C backhoe. It has about 7000 hours and starts and runs fine. I've only had it for a month or two and only used it for about 10 hours to this point. Haven't really gotten to know it yet and this is my first diesel.

Was out using it this morning for about 3 hours trying to stabilize a road between two fields. Worked it pretty hard trenching, moving previously piled dirt into the road bed, hauling limestone base about 300 yards and only got it stuck once. First time I had to learn how to use the boom to get myself unstuck. :D

About two hours in it died once. Suddenly and without notice. I had checked fuel and knew it wasn't empty. It was probably at a quarter tank. But I went and got 5 more gallons just in case and put it in. She fired up and I worked for another hour. A couple of times on the 300 yard bucket hauls of limestone it seemed to gallop on me a bit.

I decided to take a break and park it back where I normally do. When I stopped, it wouldn't go down to low idle. There is no tachometer but it was idling high. I turned the key off and it kept running at that high idle - no difference. It wasn't that low, loping diesel - it was still running at high idle. I called a friend of mine over who works on diesels and he said he never saw anything like it.

With the key in the Off position it would run at high idle and the throttle would not respond. With the key in the On position the throttle would respond. We checked the electrical connections to the pump. Nothing loose but that ground needs to be cleaned.

Eventually (10 minutes of running in the Off position) it started to decrease idle and labor a bit and finally shut down. We started it back up again easily and once again it would not shut off. Again, after 10 minutes it would eventually idle down and shut off.

The fuel filter looks like it has never been touched. I'll change that merely as standard maintenance and getting to know the machine. Think I might have sucked something into the pump when it was lower but not out of fuel?

Any ideas why it is acting the way it is? Thanks.

RedDawg
 
On the top cover of the injector pump you will find the return line,it usually is attached to an elbow,remove the line from the elbow,remove the elbow,inside the elbow is a ball and spring for regulating the pressure in the pump,see the elbow is not blocked,you may find little lumps of a hard rubber like material,if you do it would suggest that the flex ring inside the pump is breaking up,test the return line to the tank is free and put the elbow and line back on and see how it reacts.
AJ
 
(quoted from post at 19:04:04 06/20/18) On the top cover of the injector pump you will find the return line,it usually is attached to an elbow,remove the line from the elbow,remove the elbow,inside the elbow is a ball and spring for regulating the pressure in the pump,see the elbow is not blocked,you may find little lumps of a hard rubber like material,if you do it would suggest that the flex ring inside the pump is breaking up,test the return line to the tank is free and put the elbow and line back on and see how it reacts.
AJ

Thanks a bunch for that. That's very helpful. Got the new fuel filter yesterday and will be tearing into it in the next day or two.

Appreciate it.

RedDawg
 
Check for 12 volts at the shut off. You need a full 12 or better to run. If you have that I would swap out the shut off solenoid. An electro magnet makes it run, a spring shuts it off. I think this is your issue. You can start and stop the engine with the cover off. It will just spill fuel out on the ground. You have to operate the linkage by hand to kill it. Push the linkage towards the drive end of the pump to shut it down. If it idles and cranks up fine without the cover and shuts down with pushing on the linkage you have a solenoid problem. with a broken flex ring you will see the pump full of what looks like coffee grounds. I have never seen this cause a pump to not kill, but it will kill a pump and not let it restart. Bad solenoids are not that uncommon. Al
 

Thanks, I'll be tackling this tomorrow. Time to tear into it. I'll post back with what I find.

Thanks again.

RedDawg
 

Changed the fuel filter (that's an interesting configuration). Filled it with diesel. Added a pint of Sea Foam. Cleaned up the electrical connections to the injector pump.

Starts and runs fine - and shuts off properly. Won't really put it to hard work until tomorrow when we trench a water line. Changed the bucket today to a 12" bucket and will trench in heavy clay in the morning before it get too blasted hot.

Thanks everyone! I'm learning this machine.

RedDawg
 

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