John Deere 710 dies/wont start when warm

[alaskasmitty]

Our JD 710D won't start again after using it for awhile. Sometimes its only after 30 min, sometimes after 3hrs. Give it a little time or overnight and it will start right up again. Its a Stanadyne rotary pump. I replaced the fuel shut-off solenoid. The mechanic before me replaced the whole pump. When it dies, I have tried bleeding the system and still nothing. I don't notice any bubbles either. I ran a hot wire to fuel shut-off solenoid, still nothing. I sometimes get an alarm, but of course being old and in rain forest country here in Hawaii. The alarm board is non- functioning and obsolete. If i'm not mistaken a major alarm can shut off engine but it can only do this by shutting off fuel solenoid, so by running hot lead to solenoid it should work even if there is an major alarm, again if i'm not mistaken. There are no other electrical leads going to engine. (of course oil & temp senders) I checked gas cap for not venting, I replaced tank inlet screen, Replaced all rubber seals on fuel lines. Its funny because if I leave engine running it takes along time before shutting off, but if I shut off after 30-40 min or so it won't start again. Have to wait and it starts right up. The engine runs strong when working. I've been wrenching on heavy equipment and marine diesels over 30 years now and this one has me stumped. Any ideas??

 

[Delmer]

How about your fuel return? try replacing that line back to the tank and see what happens. Only other thing I can think of is to tee into the fuel supply line before the injection pump and run a line to a vacuum/pressure gauge in the cab to see what's happening when it dies/won't start. I wanted it to be the inlet screen so bad... Or three bad fuel solenoids??? Do you have any other rubber lines on the fuel system in this? I've had suction leaks act like that.

The alarm won't shut off the engine on the JD monitors that I'm familiar with, somebody else might know for sure on this one.

 

[alaskasmitty]

Thanks for the comeback Delmer. I will try those things in the morning. I tried loosening the return line that goes back to pump, thinking it would relieve any pressure but no difference. I haven't messed with the main return line. I wonder too if my inlet line from tank to supply pump might be collapsing on inside??? I tried to order one but of course obsolete. I'm sure I can get a hose made locally, but it has those funky fittings with rubber washers. But I seem to have good flow when using priming lever on supply pump. I was also wondering, if by chance I was getting air into the system somehow, wouldn't I have to bleed before starting again. I don't have to do anything after it sets, it just starts right back up.

 

[Delmer]

the return line at the pump is what I was talking about. Does it go up to the injectors and back to the tank? If you loosened that and it didn't help, then that's not the issue.

A hydraulic shop (or even auto parts store that makes hoses) shouldn't have any problem with those flat face O ring fittings. If you want, you can take the old hose, grind the collar off on a bench grinder and chisel it off the hose, then grind through the hose enough to get it off of the barb. Then any rubber fuel hose and a couple hose clamps will work just fine. Rinse off the grit first.

The priming lever can tell you what's going on if you pay attention to how much pressure it has when pumping fuel, vs pumped up to pressure (not pumping anymore), vs sucking air, vs sucking fuel against a vacuum. The priming pump isn't next to the injection pump though, and that's the pressure that matters.

 

[thepumpguysc]

You are correct in assuming the "fault" shuts off the electric sol. in the inj. pump.. so hot wireing will by-pass the shutting off due to a fault code..
Its been my experience on those doing the same thing is> rust in the fuel tank.. A LOT of rust.. & bad lift pumps.. just because the hand primer works doesn't mean the pump works..
Isnt there a sediment bowl on the other side from the inj. pump?
The reason that I've come up with when I was diagnosing one is> the lift pump was bad, there was A LOT of rust in the tank, the customer didn't know about the sediment bowl & filter..
What was happening was the main filter would fill by gravity after waiting.. overnite, 3-4 hrs.. & the pump would pump.. The inj. pump has a supply pump IN IT & would suck enough after start-up to keep it running.. BUT if it was shut down.. the main filter was just about empty because of the bad SP & clogged sed. bowl that it wouldn't start back up.. UNTIL the main filter had enough time to refill..
I'll bet w/ some well placed gauges{psi/vac} you'll find a blockage.. and/or very low pressure..
Good Luck

 

[Grady]

It's nice to get the "dirt" behind the diagnosis. Thanks pumpguy & Delmer.

 

[jimg984]

take return line CONNECTOR off at inj pump and clean make sure the ball check valve is working

 

[thepumpguysc]

That's how I would start the diagnosis jim.. I keep a return connector w/ a smashed out ball in my tool bag..
just for situations like this..
On some of these units the return fuel goes back to the filter head.. so if the connector is removed to test for a blockage & the engine is cranked.. u suck abunch of air into the system & defeat the purpose.

 

[alaskasmitty]

thanks for all your replies. Ive been off since Thursday and haven't had a chance to do any thing with it yet. Couple comments. I'm not familiar with the check ball you are talking about. Where is it located? I don't have a sediment bowl after supply pump, it goes directly to fuel filter. (only one filter on system). The return line goes to top of injection pump and other goes back to tank, nothing returns to filter head. Regarding other comments. I completely cleaned this tank and replaced fuel inlet screen. Also the fuel suction lines to supply pump are not flat face o-ring style, they are a compression type with a rubber collar. I have replaced all these rubber collars but still kind of a unique fitting. They can swivel even after tightening.

 

[alaskasmitty]

I don't see a check ball on any diagrams. Is it inside of elbow fitting on top of injection pump, that return line connects too?? It makes sense there should be some kind of check ball. I just don't see one anywhere. When I disconnect that line and pump the hand primer fuel does come out at top of injection pump. (where return line connects)

 

[thepumpguysc]

You haven't given me any pump #'s to work with, so I cant tell u for certain it has a check ball..
BUT YES, it would be in the fitting on top of the pump{return}
I hate those "rubber sealed" connectors.. cuz just like u said.. sometimes you can still swivel them after tightening them down..
If u can.. run the machine without the check ball fitting & see what it does.. just put a "barbed" fitting in its place & run a hose off of it, to the return line back to the tank..

 

[alaskasmitty]

thanks for your help pumpguy. here 's a pic of label if it helps

 

[alaskasmitty]

I don't see a check ball anywhere. There's nothing inside the elbow and nothing inside the return line connecting to it. When I run machine with line disconnected it runs out of pump but nothing comes through return line from injector return rail. Ther is also nothing in parts diagram. Have factory parts list for pump and John Deere web site for parts. Don't see anything indicating a check ball

 

[mg2361]

That is a DB4 pump. The straight return fitting (first fitting attached to the pump) that sticks out of the top of the pump is the check valve. Did you try to loop a clear line into the fuel return line and run it. Lots of bubbles you know it is an air infiltration or vacuum issue from a restriction.

 

[thepumpguysc]

IT DOES HAVE 1.. 1st fitting next to the cover.. 9/16 wrench.. then all the other fittings{brass} get screwed into IT..
Your JD manual isn't gonna show it.. cuz its a Stanadyne pump & part.. NOT JD..
P#> 22109

 

[alaskasmitty]

I saw that part in the Stanadyne factory parts list. It doesn't mention or show any kind of ball, but must be inside. So just to be clear if that check ball is there, there shouldn't be any fuel coming out of fitting when primer lever is pumped?? The machine is out in the field and can't look at it right now

 

[hosspuller]

As I understand the Stanadyne pump, the check valve is to keep the fuel flowing through the pump. As the injection pump pushes fuel to the injectors, it sucks fresh fuel from the filter. Without the check valve it could suck unfiltered fuel from the tank via the return line.
So … no ... there Could be fuel coming out of the check valve when the primer is pumped.

 

[alaskasmitty]

now that I look at it, I guess is opposite of way I was thinking. Looks like it won't let any return fuel go back into pump. What is its purpose, pressure relief for top of pump, allows air to escape??

 

[alaskasmitty]

Thanks hosspuller. I was writing my reply when yours came up. I could see how maybe could suck air from return if not working properly. or like you say keep fuel flowing through pump. got to look at it a little closer

 

[thepumpguysc]

Its only purpose is to maintain a certain pressure inside the inj. pump to aid in the advance piston {timing}movement..
BUT if its partially clogged it will have an adverse effect on starting..
YES, it will allow fuel to be pushed out while priming..
All I can tell u is>> it's supposed to have a f'n check ball return connector & take it out to diagnose.!!