JD 670 Compact

[Rich.Fl]

A friend has a JD 670 compact tractor with a 3 cylinder Yanmar diesel engine. It has been lightly used; only about 400 Hours on the engine. It sat for close to a year, then when tried would not start.

I have drained the fuel tank and put in fresh diesel. The manual says the engine is Self Bleeding, but since could not start after multiple tries, bled the banjo fitting going into the injector pump (pic 1)...fuel flowed out well. Still would not start.

Then tried to bleed the 3 fuel lines going into the injectors (pic 2.) No fuel after multiple times cranking the engine.

What to do next??

Rich

 

[wore out]

I'm sure you've observed the shutdown solenoid ''pulling in'' when you crank the engine?

If that is working, likely the ''rack'' in the injection pump is stuck in the''no fuel'' position.

 

[Dieseltech]

Remove ALL head glow plugs to relieve engine compression so engine cranks faster, loosen ALL injector lines at the injectors and make sure the stop solenoid is working and try again. If you still have no fuel at injectors, the injection pump has one or more plungers stuck which keeps the rack from moving. If you do get fuel, tighten the lines and crank again until you see air/fuel mixture blowout the glow plug holes, replace the plugs and start engine. I bleed any glow plug type engine this way as it's easier on the battery and starter.

 

[Rich.Fl]

I had not even thought about the fuel shut off solenoid. (I am use to my old tractors with a manual shut off, and am not much mechanic Checking that seems like the next step. I assume the solenoid is what I have the arrow pointing to in the picture...and I should see it move when the key is turned on?

Thanks for the help!!
Rich

 

[wore out]

Yes, you have found the fuel cutoff solenoid!

It should ''pull in'' when you first engage the starter, then stay latched until the key is switched ''off''.

 

[Rich.Fl]

Well...the good news is when the tractor was cranked the fuel solenoid did not move. When I pushed the shaft/lever in the little tractor fired right up and ran perfectly. There is a connecter to the fuel solenoid with three wires going in and out. I pulled it apart and checked all combinations of the plug with a volt meter..no current. (Truthfully I do not understand three wires on a 12v DC system...maybe ground, neutral and positive?)

I have an IT shop manual for this. Looks like there is a solenoid relay switch. I am guessing this would be the next thing to check? The wires from the connector disappear into a wiring harness. The shop manual does not show the location of the relay and I was reluctant to start tearing things apart before knowing a bit more.

Anyone have a guess where the relay would be? Is that the next step? Maybe under the dash?

Thanks!
Rich

 

[Rich.Fl]

Thanks for this information on bleeding a diesel. Looks like I won't need it for this tractor, but I will definitely file it away for future use.

Thanks!
Rich

 

[Scott 730]

(quoted from post at 20:36:29 10/21/22)
Truthfully I do not understand three wires on a 12v DC system...maybe ground, neutral and positive?)

IIRC there are 2 coils in the solenoid. 1 gets powered for a short time only to pull it in. The other one holds it in until the key is turned off. Thus 2 hot wires and 1 ground in the harness.

This post was edited by Scott 730 on 10/21/2022 at 07:12 pm.

 

[wore out]

Yes, there are two coils/electromagnets in the unit that share a common ground connection.

One coil draws low Amps, this is the ''hold'' coil. It doesn't make enough magnetism to pull the plunger in, but can hold it in once the stronger coil/electromagnet pulls it in.

When you switch the ''ignition'' ''ON'' (IF the safety switches are satisfied) the ''hold'' coil is powered, but the plunger doesn't move.

When you crank the engine a relay is activated (along with the starter solenoid) that temporarily powers the ''pull in'' coil and at that point the ''hold'' coil will keep the plunger pulled in 'til the ''ignition'' is switched ''OFF''.

IIRC, the BLACK wire is ''ground'', the RED wire is ''hold'' (draws 5 Amps, or less), and the WHITE wire is ''pull in'' (draws, IIRC, 30+ Amps).

 

[Rich.Fl]

Scott and Wore Out-

Thanks for explaining the 3 wires...that makes sense. Is the relay the likely culprit- the next step?

Rich

 

[farmallfletch]

Scott and Wore Out-

Thanks for explaining the 3 wires...that makes sense. Is the relay the likely culprit- the next step?

Rich

Hi Rich, it doesn't look like anyone replied and you've surely fixed it. I came across this thread because I had the exact same issue with a recently acquired 670. On mine it turned out to be a blown fuse. There are two number 3 fuses. I replaced the blown one which powers the shutoff solenoid. Hope this helps to others who may come across this issue.