Re: Westerbeke diesel will not start
Skipper Jer, fair question, not sure. One idea. If the OP tested the fuel flow/spray by running the lift pump or his new bypass pump connected directly to power, not while the engine was actually cranking, then the sensor fail-safes were out of the loop. This would possibly explain why a squirt of any sort of starter fluid would get a brief ignition. The engine wants to start but it isn't getting fuel while cranking, maybe because the oil pressure failsafe circuit is saying shutdown.
Another lesson from my (stupid) incident above. My main engine wouldn't start at all, but the genset would start and run as long as I held the "preheat" button down. When I let go of the button it stalled. The main engine does not have a separate pre-heat button, just a rocker switch with one side as preheat and the other as crank the starter (which also lights the glow plugs during the cranking). These two different behaviors taken together confused the heck out of me for a while (and eliminated fuel as a problem). The lesson is that while in preheat and while cranking the oil pressure failsafe is bypassed so the engine can start (I knew this before but it just wasn't clicking in my brain then). So my genset kept running if I held down the preheat button because it had taken the oil pressure failsafe out of the loop, and the fire suppression system uses the same failsafe circuit, so when I let go of the button the fire suppression circuit killed the fuel flow. I'm sure the main engine would have behaved exactly the same way if it had a separate pre-heat button.
In my system the low oil pressure switch (different than the oil pressure sensor) is normally closed when the engine is cold and has no pressure. In this position it sounds the low pressure buzzer and kills the fuel pump (except while bypassed in preheat/crank). When the oil pressure builds (almost instantly) the switch opens and the circuit is happy and the fuel pump gets power. The super easy way to test this is just take the wire off the oil pressure switch making it open. Then crank. Of course other engines might be different.