Generator engine stopping

[TBW]

Genset has 4 cylinder Isuzu engine. Oil, water good. New oil pressure sensor, new fuel solenoid shut off.
Problem - starts easily. As soon as I take my finger off the start switch (3 position rocker switch - off, power, start) the engine stops. Right now.
Engine has been running fine for long periods of time.
Something is telling it to shut down. Oil pressure sensor was a very popular candidate at the dock in Chub Cay. No joy.
My problem is trying to find out what else to check or change.
In Stuart, Fl trying to get back to Maryland but not really willing to go without genset. If I hold the start switch down, the engine keeps running just fine - but displays no oil pressure, water temperature or volts.
Any thoughts, ideas or advice greatly appreciated.
TW

[rolandcavanagh]

Check for other safety sensors, my westerbeke has two overtemp switch sensors (exhaust, coolant) in addition to the low oil pressure switch. I chased the same problem twice as one sensor after another failed months apart.

[TBW]

Follow up to above.
Mechanic came (on Sunday morning!)
The oil pressure sender that diesel parts sent was what was needed.
I (me) put in the front which was the oil pressure switch.
Mechanic put the new sender on the other side of the engine where it was needed and put the original pressure switch back where it came from and all is well.
All I need now is a good picture of the engine with all of the various senders and sensors labled.
TW

[Cheechako]

Such a common problem on many modern generators. Especially Panda and Westerbeke. First thing I would do is bypass all the 'autoshutdown" stuff!
Your main engine doesn't shut down due to a bunch of sensors does it? One wonders why they put that crap on Gens........

[rolandcavanagh]

Originally Posted by Cheechako

Such a common problem on many modern generators. Especially Panda and Westerbeke. First thing I would do is bypass all the 'autoshutdown" stuff!
Your main engine doesn't shut down due to a bunch of sensors does it? One wonders why they put that crap on Gens........

To prevent them from destroying themselves when something is wrong… generator use is ‘nice’ but not critical like the mains. My main has really loud alarms, but doesn’t shut down, meaning that I can burn it up if really necessary, for instance to avoid a Lee shore.

[FPNC]

The run solenoid is not holding. Either a bad solenoid or current is not getting to the solenoid hold coil.

[rslifkin]

Beyond checking the auto shutdowns, also confirm the unit is outputting power when it starts. Some gens (including my Onan) won't stay running once you release the switch if there's no 120v output.

If I remember correctly, mine won't detect engine start if there's no 120v output, so the starter will stay engaged (normally once output voltage comes up the starter drops out even if you continue to hold the start switch). The safety shutdowns stay bypassed until the switch is released (procedure for mine is to hold the switch until it spins up to speed, if you release as soon as soon as it fires it may not have enough oil pressure yet and will die when you release the switch, but the extra second to get up to speed is plenty of time for it to be happy and stay running).

Originally Posted by Cheechako

Such a common problem on many modern generators. Especially Panda and Westerbeke. First thing I would do is bypass all the 'autoshutdown" stuff!
Your main engine doesn't shut down due to a bunch of sensors does it? One wonders why they put that crap on Gens........

Generally a main engine is monitored more carefully while in operation. On my boat, if the mains are running, someone is sitting at the helm with a bunch of gauges in front of their face (and warning buzzers for high coolant temp, low oil pressure, and high trans temp). Plus, with a main, an auto shutdown can be a safety issue. So it's better to warn you and let the operator choose to damage the engine if loss of propulsion at that exact moment would be dangerous.

When my generator is running, however, other than hearing it running and confirming cooling water flow at startup, nobody is paying attention to coolant temp, oil pressure, etc. And an unexpected shutdown won't put the boat on the rocks in a narrow channel.

If the auto shutdown system is decently designed, they're generally reliable. If it's not a reliable system, it's worth some effort to fix it. On my gen, for example, there are 4 switches that'll shut it down: 1 for low oil pressure, 2 for high coolant temp (1 on each cylinder head as it's a boxer twin layout), and 1 for high exhaust temp on the exhaust elbow (generally that will trip first if it loses cooling water). 36 years and ~1440 hours and those shutdowns have never been problematic.

[Lepke]

The start button (while pressed) on almost all generators bypasses the safeties - oil, coolant temp, exhaust temp. If there's a bad safety or bad wiring in the safety circuit, the engine will stop every time the button is released.