JD750 Fuel Issues? Water contamination?

[dodge man]

I’d check the lift pump too. I assume it has one. You should be able to hear it clicking if you turn the key on but don’t start it. Does it just have one fuel filter? I’m not familiar with yours but on a lot of newer JD uses two filters. I suspect yours just has one.

 

[California]

Which a bad VR can cause. If the vr is not cycling properly, the battery can indeed fail to charge. Headlights can also be dim and instrument panels can be wonky. The voltage regulator controls the flow of electricity to every working part, including the engine. Bad voltage regulators have been known to cause engine stalling, acceleration issues, irregular engine timing, and misfires.

But not on the Deeres built by Yanmar. Yes a low battery will have dim headlights and dash lights. And obvious slow cranking before the engine fires.

But there is nothing electrical on these diesel engines aside from the fan belt driving the alternator, and the temp and oil pressure senders. No control mechanisms.

Also no electric lift pump. Just gravity from the tank to the fuel filter and down to the injector pump.

No fuel shutoff solenoid. (At least on the near-twin Yanmars, I don't know if Deere added one).

These Yanmars and Yanmar-built Deeres from that era are elegantly simple.

 

[arrow]

But not on the Deeres built by Yanmar. Yes a low battery will have dim headlights and dash lights. And obvious slow cranking before the engine fires.

But there is nothing electrical on these diesel engines aside from the fan belt driving the alternator, and the temp and oil pressure senders. No control mechanisms.

Also no electric lift pump. Just gravity from the tank to the fuel filter and down to the injector pump.

No fuel shutoff solenoid. (At least on the near-twin Yanmars, I don't know if Deere added one).

These Yanmars and Yanmar-built Deeres from that era are elegantly simple.

If the vr is on the way out, at around 13 volts, the tractor will start to drain the battery. When this happens, it’s only a matter of time before the engine stops completely.
.

 

[California]

So you're saying the vr is strictly on the starting circuit on these?
No oil pressure shut down?
.

Nope. None of that fancy stuff. Only a low-oil-pressure light on the dashboard. Likewise no temp gauge, just a light warning its approaching boilover. Which it won't so long as the radiator is clean.

The smaller Yanmars didn't even have a water pump, just 'thermosiphon' like a Model T. Which actually works fine.

I have a US-Yanmar YM240, their adaptation of the Japan-market YM2000. Over-run clutch in the pto and a ROPS were the only notable changes, to meet US safety standards. Its operation manual still has some of the really simple old-school instructions from the Japan market, including draining the cooling system off-season and how to run with no battery. (I guess in tilling or harvest season a battery is carried around to all the tractors that will work that day??). The manual says replace the oil filter after 2 to 3 oil changes.

There's nothing more than the essential basics on these, and then designed for the owner to do any needed repairs. Think of a tractor designed to be shipped to some remote market to survive without dealer support for decades.

If the alternator and mechanical VR look familiar, they are, Yanmar used the same ones as similar year Datsun/Nissan which makes replacement simple anywhere. Under $50 today for both.

The Deere versions from early 80's should be about the same as what I'm describing.

 

[Oaktree]

Had a 750 before I got my Kioti, and agree there's nothing electrical in it that can cause this, even if you turned off the key it'd keep running. I'd lean towards the crud-in-the-fuel-tank solution. Is there some sort of pre-filter in the tank that might be clogging up?
Another thought, IIRC, the fuel cut off was controlled by the throttle lever...pull it all the way toward you (lowest idle speed) and it would shut off the fuel. Since the problem seems to mostly happen at idle, I wonder if the linkage is messed up somehow.

 

[5030]

Sounds to me like you are a prime candidate for a Racor Style fuel polishing unit.

 

[wamendt]

Background: FIL gave me his late 80s JD750 tractor w/ 70 series loader. FIL is a GREAT guy -but when it comes to vehicle / equipment maintenance not so much. This tractor was not worked all that hard in the last 30 years. 1400 hours total on it now. He bought it used probably 30 years ago. When I got it, it had no fuel filter in it. Replaced entire bowl assembly / filter with JD parts. Changed the oil / filter (don't get me started how old that might have been in there. It turns over A LOT easier now LOL.

Replaced dry rotted fuel feed hose from tank to filter housing. Same on the line from filter to the injection pump. Fixed a leak at the injection pump bleed screw with new washer / screw. At that point tractor started and ran well. Worked it around our property a good bit. Tractor sat for 3-4 months (lots of other stuff going on). Got it started it up, running fine, one of the hoses on the loader decided to go boom. Found a local place that made a new hose ($45 not bad). Filled hydraulic system, loader works great.

Worked the tractor clearing brush etc for a week or two. No issues. It sat for 4-5 days. Went out to start it up yesterday to work some, it immediately cranked right up and idled fine. Looked at the fuel gauge (mounted in the fuel tank cap). Saw it was low. Cut the tractor off. Put in a few gallons of fresh diesel. Started it back up - runs fine for maybe a minute, then it started stumbling and just died out. Wouldn't start back up. Drained the sediment bowl, cleaned the fuel filter (newer - looked fine). Drained a bit of fuel from the tank into a bucket just in case some water got in the fuel. Hooked it back up, bled fuel filter bowl, bled at injector pump, didn't want to go.

Followed JD procedure - Bled filter bowl>injector bleed screw>loosened delivery holders (1 and 2 only)>loosened all three injector lines. Cranked tractor over. Got what looked like white cloudy mess from top of injector pump and a bit of this from injector lines at engine. Figured water must have gotten in it. Which was odd. Not much rain since I last ran it. Anyway, drained some more fuel from the tank, bled everything.

Fired RIGHT up ran good. Let it idle for a bit. Walked back to my shop to put my tools up. As I got to climb up on the tractor, it starts idling down. Even at higher throttle, it just idled down then slowly died. Cranks RIGHT back up, runs for a bit, then dies out. Bled it again - same deal.

Got a hold of the JD service manual, going to pull the fuel tank (there are a couple of things I want to check out in the electrical anyway - tach cable jumps around something fierce). Figure I'll pull the tank, manual clean / flush it out, then fill it with fresh fuel / bleed and go from there.

Any ideas? Common things on these tractors? I am going to replace the vent hose from the tank to the engine - it's dry rotted / cracking bad.

Any recommendation for additive to deal with condensation / winter etc? (tractor is stored outside for now - no choice - shops are full).

Thanks!

My 5520 was doing the same thing. No water in fuel issues but the fuel lines were cracked and able to suck air took quite a while to figure it out because it was somehow intermittent. Replaced the fuel line from the tank to the filter and from the filter to the pump and I’ve had no more issues for the last four years. And I paid extra for the Gates hose, only to find out that it’s made in China.

 

[Gord Baker]

If you feel it is not a fuel flow issue, then the next thing is an electrical problem.
On the firewall, there is a voltage regulator. These go bad and cause all sorts of problems. See if yours gets hot when tractor dies.
I had to replace mine twice on my JD 750 purchased in 1988 and sold in 2012.

JD 750 voltage regulator...204067476398

Since this is a Diesel engine, it is unlikely to have an electrical Problem in regard to running.
REMOVE and clean ALL Battery cable terminals especially Ground connection.

 

[DieselBound]

Get a separate fuel container and connect that up to the feed to your injection pump (with filter or using existing filter).

If it's determined that there isn't fuel blockage from the tank (issue persists after using a separate fuel container) then it still could be a fueling issue. Could be the injection pump is warming up and sucking in air: and any fuel lines should also be held suspect. And or fuel shutoff losing power due to electrical (mechanical?) issue.

Water in the fuel is certainly a cause for concern. And has been mentioned, check the fuel cap: I had this issue on my Kioti (I have a mental note to stuff a can over the top of my fuel tank's filler, but keep forgetting! a replacement cap has been far better but, as it too is a locking style, it's not "water proof" either.)

 

[dcarman]

It sounds like water in the fuel! It also sounds like the water was induced into the fuel system with the fresh fuel. When you run into things like this, it was running fine then I added fuel because it was low now it won't run, always look at what you did last to find the culprit. A water filter on your fueling system may be in order.