how does the injector solenoid work on a CK20S?

[DroppedAxle]

Hello Everyone.

My CK20s sat for a while this winter (no snow) and didn't get it's needed exercise (my bad). It now doesn't start and I've tracked it down to the solenoid on the fuel injector not working. (No fuel at injector nozzles but at injector bolt; no click from solenoid, but power to the solenoid.)

My question is how does this solenoid work? I see three wires entering it. In tractor direction, left to right: White, Black, Red. I assumed (correctly I think) that B is ground. I measured voltages between R&B and W&B. I see a pulse of 12V on the R&B pair as I move the key past "ACC". I also see a voltage on W&B pair as I crank around 10V (voltage drop due to cranking I'm guessing).

Anyone know how this works? If I remember correctly from replacing this 5 years ago (thread here: https://www.tractorbynet.com/forums/kioti-owning-operating/329736-07-ck20s-bad-fuel-solenoid.html) the plunger is extended to turn/keep fuel off and retracted during operation. Not quite sure what the single pulse if for...

Also, if anyone has schematics on how this wired up, much appreciated.

Thanks,
DA

 

[SSdoxie]

The single pulse is momentary high amp feed through the fuel solenoid relay to pull the internal magnetic to ON position. The white wire is lower amp constant volt to hold solenoid in ON/Run position. If the solenoid connects to a cam lever going into the fuel rail (early models), the shaft going into the pump housing was notorious for rusting and seizing so the solenoid can not move it far enough to move the fuel rail to full ON. Spray that lever with some type of rust buster then move the lever by hand to free it up.
If the solenoid bolts directly to the front of the injection pump, or if lubing the lever doesn't fix it, check OHMs resistance at R to B wires for possible open circuit in the solenoid.

 

[DroppedAxle]

Thanks Dennis.

So the constant low amp current is to keep the plunger retracted when running and the momentary high amp pulse is used to jolt the plunger in initially? That makes sense.

Guessing I have to pull the thing now in order to lubricate (if rusted in place) and/or replace...

DA

 

[SSdoxie]

Thanks Dennis.

So the constant low amp current is to keep the plunger retracted when running and the momentary high amp pulse is used to jolt the plunger in initially? That makes sense.

Guessing I have to pull the thing now in order to lubricate (if rusted in place) and/or replace...

DA

Disconnect solenoid from the injection pump lever then turn key to Start and see if solenoid cable moves. If it still does not move then solenoid is the problem. While cable is removed spray the lever shaft with PB Blaster or similar penetrating fluid and work lever until it moves freely.

 

[DroppedAxle]

Disconnect solenoid from the injection pump lever then turn key to Start and see if solenoid cable moves. If it still does not move then solenoid is the problem. While cable is removed spray the lever shaft with PB Blaster or similar penetrating fluid and work lever until it moves freely.

Thanks, but I don't think I have a solenoid cable! There's never been a cable there, but I bought the thing 2nd hand five years ago. There is a linkage right above it, next to the fuel injector, but it's not connected to anything and it moves freely. I'll send a pic in the morning.

 

[ritcheyvs]

I think you have the second version where the stop solenoid (SS) bolts to the front of the engine with no external linkages. In this version, the SS plunger is spring-loaded to the extend position which pushes the injection pump rack to the full-off (zero fuel) position. The SS must be retracted before the injection pump can deliver fuel for the engine to start or run.

The SS has two coils: the high current "pull" coil that gets a short pulse to retract the plunger against spring force and the low-current "hold" coil keeps the plunger retracted as long as the key is ON. The pull coil is powered through the stop relay. The hold coil is powered directly from the key switch.

Can you hear the "clack" of the SS retracting when the key is switched from off to on? If not, the solenoid is not retracting. That could be electrical (fuse or stop relay) or the actual SS.

If the SS clacks when you turn the key on, see if it clacks again when you turn the key off. If not, the "hold" isn't working and the SS doesn't stay retracted. If the SS retracts but doesn't stay retracted the most likely cause is the key switch. The contacts in the switch often become unreliable because of corrosion, dirt, and dry grease. Squirt WD-40 in the key hole and cycle the switch several times. This is good annual maintenance regardless.

 

[DroppedAxle]

I think you have the second version where the stop solenoid (SS) bolts to the front of the engine with no external linkages. In this version, the SS plunger is spring-loaded to the extend position which pushes the injection pump rack to the full-off (zero fuel) position. The SS must be retracted before the injection pump can deliver fuel for the engine to start or run.

Yes, I have a linkage arm that moves freely, but no cable. Pic attached.

The SS has two coils: the high current "pull" coil that gets a short pulse to retract the plunger against spring force and the low-current "hold" coil keeps the plunger retracted as long as the key is ON. The pull coil is powered through the stop relay. The hold coil is powered directly from the key switch.

Can you hear the "clack" of the SS retracting when the key is switched from off to on? If not, the solenoid is not retracting. That could be electrical (fuse or stop relay) or the actual SS.

The SS is energized (see first post) correctly I think. There's no clack though. Gonna pull it this morning and test.

If the SS clacks when you turn the key on, see if it clacks again when you turn the key off. If not, the "hold" isn't working and the SS doesn't stay retracted. If the SS retracts but doesn't stay retracted the most likely cause is the key switch. The contacts in the switch often become unreliable because of corrosion, dirt, and dry grease. Squirt WD-40 in the key hole and cycle the switch several times. This is good annual maintenance regardless.

Thanks!

 

[DroppedAxle]

Yep, solenoid seems dead. Pulled it but kept it connected to the electrical. Moved key through all positions and no movement of the plunger; stayed fully extended. Jiggled it a bit, but still nothing. Ordering a new one. The good news is that I saw white smoke with a short cranking so this was definitely the problem.

 

[DroppedAxle]

Ordered a new solenoid and O-ring from MIE. There's another part, the solenoid guide that was out of stock but I don't think I need that so didn't get it; anyone know what that is?

 

[ritcheyvs]

Yep, solenoid seems dead. Pulled it but kept it connected to the electrical. Moved key through all positions and no movement of the plunger; stayed fully extended. Jiggled it a bit, but still nothing. Ordering a new one. The good news is that I saw white smoke with a short cranking so this was definitely the problem.

It is still possible there is an electrical problem. If you measured voltage pulse with the SS disconnected it is possible to see a good 12v even when failing relay contacts will not pass enough current. The acid test would be to jumper the SS "pull" contact to the battery + terminal momentarily (less than a second).

SS relay failure is common but SS failure is rare (although it has happened). The SS relay is the same as the starter relay and temporarily swapping connectors between those two relays is a common troubleshooting method. The actual relays are common automotive parts available at any auto parts store (and very cheap in quantity on ebay).

Do one more thing: test it again with the solenoid case grounded to the engine. In some versions, the electrical ground path was through the case/engine, not through a wire. You have three wires so that should not be the case but check anyway.

If it still does not retract, can you push the plunger in by hand? If you can the solenoid is bad and must be replaced. But one owner had a situation where engine oil got inside the solenoid and hydraulically locked in the extended position. He drained the oil and the solenoid worked again (don't know how long).