Kioti LK35 Injector Pump Solenoid Problem

[KiotiLK35]

I have an LK35 which recently decided to refuse to start. Have traced problem to the solenoid on the front of the fuel governor (AKA the "Stop Solenoid"). Solenoid does not latch itself and therefore the tractor will turn over but NOT start. I can get it to start by removing the inspection plate over the solenoid plunger and manually latching the solenoid while ignition is turned on. Once the solenoid is latched it stays latched until ignition is turned off, therefore I can run tractor all day if I want, but whenever I want to start it again I have to manually latch the solenoid (after removing inspection plate). There are 3 wires running into the deutsch plug on the solenoid - Blue, Black and Red/Blue. The Blue wire is active whenever ignition is turned to ON position and remains active when ignition is in START/CRANK position. I believe this wire is the one keeping the solenoid latched. The Black wire is earth. The Red/Blue wire is never active and I suspect that is my problem. I have removed solenoid to test the solenoid itself and if I run power to the Red/Blue wire it DOES latch the solenoid. If I have power to the Blue wire it keeps the solenoid latched. Therefore I conclude that the problem is I am not getting power to the Red/Blue wire at all and I suspect this should only be active when the ignition is held in the START/CRANKING position. So? my questions are

1/ can anyone confirm (or correct) my analysis/conclusions?

2/ can anyone point me to where to trace the Red/Blue wire to in order to detect/rectify the failure/disconnect? (and yes I have checked all fuses)

 

[SSdoxie]

Red/blue wire is the Pull On Circuit. The power should be coming through a relay and likely a fuse. Check for a Fuel Relay and a Fuel Fuse.

 

[ritcheyvs]

Your analysis is correct. That version of stop solenoid has two coils: a (high current) pull coil (red/blue) and a low current hold coil (blue). The intent is to save power and solenoid heating by using a low current (which is all that's needed) to keep the solenoid latched. The "pull" wire is supposed to get a 1-second pulse at +12v at some point in the start sequence. Note that this is at least the third version of the stop solenoid so there are at least two other (single coil) configurations that work completely different.

I would start by checking your fuses. You probably have a fuse labeled "engine stop solenoid" that feeds the relay that feeds the pull circuit (don't just eyeball it pull it out and check it with a meter). The next easy thing to check is the "pull relay". After that I'd have to guess because I don't have any documentation on LK models. But I'd guess the setup is close to the SE models or the EX non-US export version. If you can read a schematic, download this link, zoom in, and scan to the stop solenoid near the right side of the diagram: http://pt709.synology.me/ex-electrical.xps

 

[KiotiLK35]

Thanks very much for your responses Scott and Dennis. Have isolated the problem to the offending relay as suggested. Thanks also for the electrical schematic Scott. I have various manuals but none of them have the full wiring schema in them. I have only had one other failure with this tractor and that was when it ceased to crank suddenly about 18 months ago. That turned out to be the relay that tickles the starter motor. I only mention this because it is an identical relay to the one which has failed now. They sit side by side on the inside of the engine fire wall on RHS of tractor. So both identical (Omron) relays have now failed. Have now replaced both of them with with a different brand of relay. All up and running again now and next time I know what behaviour to expect and how to identify the problem a lot quicker. Thanks again guys. Very much appreciated.

 

[ritcheyvs]

LK: Good job!

This is not the first report of failed relays. Likely a batch of marginal parts got into the production stream. But relays are easy to diagnose, cheap, and easy to replace. I'll take a bad relay over an bad injection pump any day of the century.

 

[KiotiLK35]

Good point Scott. Unfortunately I already bought a new Stop Solenoid last week thinking that was the problem. Cant return it to the supplier so now I have a spare of something that was never broken….. and therefore probably never will. The price of experience!

 

[bubbazoo]

Just reviving this old thread as i have had the same fault with my LK35 i think. Mine was intermittent some days it would not start just cranked over. come back in a few hours the it would start it would start all day then fail to start just out of the blue. I looked up my LK30 workshop manual same basic tractor just 5 HP less. In the electrical diagram i noted that the starter circuit also uses an identical relay so i swapped the relays over thinking that if the fault was in the fuel solenoid stop relay then the starter motor would not work. Wrong engine cranked over fine but still no fuel. Back to coffee and circuit diagram was thinking of connecting a wire to the stop solenoid to test by putting 12 volts directly on it. Whilst checking out the diagram i noted that the Solenoid current should be 36.5 amps Ok so why are these factory fitted Ormron relays only rated at 30 amps, I found an 25 year old 40 amp relay in one of my junked vehicles and put it in Tractor starts every time so far. I have disassembled the original Relay and note that the contacts are badly pitted. So at the moment i conclude that the factory supplied Blue Ormron relays are under rated for the job. Also as the the tractor battery gets older and in the cold weather like we have at moment the volts will be lower when cranking this in turn will cause the solenoid amps to go higher still, putting even more stress on the relay contacts, So LK30 / LK35 owners be warned! buy quality 40 amp relays