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Curtis B.
Curtis B., Technician
Category: Small Engine
Satisfied Customers: 25688
Experience:  have worked on and around most engine models for 35 yrs./Polaris ATV expert
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I have a Countax mower with a Yanmar twin cylinder diesel

Customer Question

I have a Countax mower with a Yanmar twin cylinder diesel engine. It's done 116 hours only. It starts then the rev counter flashes all 0000's for a few seconds, then it stops. It will start immediately but does the same.
I've checked the relays, fuel solenoid and replaced the main pcb - still no change.
Any ideas?
Submitted: 4 months ago.
Category: Small Engine
Expert:  Curtis B. replied 4 months ago.

model number? You are loosing electrical, which lets the fuel solenoid relax, killing the engine. Sounds like a loose connection, at starter solenoid or keyswitch.

Customer: replied 4 months ago.
It's a D50LN with a twin cylinder Yanmar diesel motor. Obviously I believe the fuel solenoid is switching off as that is how the engine is stopped, BUT the fact that the rev counter count disappears (usually 2750 when in operation) and flashes 0000 for about 10 seconds before the engine powers down leads me to believe that that the engine is switched off under machine control. That is, it assesses there is a problem. There are no loose connections that I can see.
Customer: replied 4 months ago.
By the way - I have seen EXACTLY this fault reported on other forums and nowhere can I find that anyone has provided an answer! The manufacturers have a service desk that is about as useful as a chocolate fireguard, they probably do not even know what colour their machines are finished in as the advice I have received is absolutely ludicrous. It took me three weeks emailing and writing letters to even secure a wiring diagram out of them although they did send me some relays. When I asked where they were physically located the tech support had to admit he did not know!
Expert:  Curtis B. replied 4 months ago.

# ***** and # ***** are the only parts that look to be capable of shutting off the system. The relay with diode, and the heat switch, what ever that is! See wire loom picture.

Customer: replied 4 months ago.
Hi Curtis
Neither of these items are the fault - I have replaced the relay and pcb, also fuel solenoid. NO CHANGE.
Expert:  Curtis B. replied 4 months ago.

Something is killing the electrical. Engine should have oil pressure switch and water temperature switch. Either would kill engine.

Customer: replied 4 months ago.
Hi Curtis. Indeed. To my mind there is a deficient input to the controller pcb saying something is amiss. It is not just the engine cutting out, but as the display shows all flashing 0's I believe something is being detected that causes the controller to make the decision to shut the engine down. If I bypass either of these devices the engine does not even start so I do not believe either is at fault.
Expert:  Curtis B. replied 4 months ago.

you are unplugging the switches? They may be normally closed. (grounded) and break the circuit. Try grounding them with a jumper wire.

Customer: replied 4 months ago.
I've done both. I know I have they are fine because if I disconnect them one at a time the engine will not start, but does when corrected. I am at a loss and the grass is now 18 inches high! On a form I did pick up that a "purple wire could be damaged" but I can see NO purple wire in my loom!
Expert:  Curtis B. replied 4 months ago.

For a way to use the mower, remove the fuel solenoid, that will keep the engine from shutting off. Not a fix, but it will get grass cut!

Customer: replied 4 months ago.
Hi Curtis. Oh were it all so easy! If I remove the solenoid the fuel line is open and would leak diesel. If I remove the 3 pin plug to the solenoid the motor will not run. I GUESS I may better need to take a live line to the solenoid, but am unsure which pin that would go to?
Expert:  Curtis B. replied 4 months ago.

It goes to the wire that has voltage when the key is turned on. The other is the wire that is live when cranking only, and has to pull the solenoid into place.

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