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Old 05-02-2016, 10:04 AM   #1
Shoalwaters
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City: Rodney Bay Lagoon
Country: St. Lucia, West Indies
Vessel Name: "Dragon Lady"
Vessel Model: DeFever 41
Join Date: Feb 2008
Posts: 681
Kubota engine on Phasor genset wants pre-heat

I have a 6.5 KW Phasor generator with about 300 hours on it. The motor is a 3-cylinder Kubota D905. Location is the Caribbean, so ambient temperature is always above 80F.

Two weeks ago I tried to start the generator after 6 months of not using it. It swung easily, but with no signs of life. Previously it had always started first push of the button and never required pre-heat. In fact, I had concluded that the pre-heat was disabled because there was no solenoid "clonk" when the heater switch was pressed - turns out there is no solenoid; the current for the heaters passes directly though the toggle switch!

I replaced both fuel filters, cleaned the strainer in the lift pump and bled the whole system. This particular motor requires 12 volts to run. I temporarily removed the stop-solenoid (technically a run-solenoid) which takes all the normal culprits like oil pressure and coolant temp switches etc out of the equation. Nothing! The stop-solenoid pushes on a lever in the injector pump to stop the engine. I checked that this lever was free to move and was in the "run" position. Nothing!

As a last resort I tried about 5 seconds of pre-heat and Voila! it started and ran. This is repeatable: the engine now requires pre-heat to start from cold, and re-starts easily without it when hot.

The need for pre-heat is not an inconvenience and, I am told, is common on small Kubotas.
The question is: What has changed and should I be concerned?
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