Westerbeke running problem

[Daddyo]

My 7.5 kw Westerbeke (Perkins engine) stops running when you release the momentary preheat/oil pressure bypass/ electric fuel pump switch. It's an instantaneous shut down like the kill switch is activated, not a fuel issue. I'm thinking it's either a bad kill switch that has shorted or the preheat etc. switch is bad although that seems unlikely as it works when activated. Any thoughts?

 

[tinped]

possibly a bad holdown relay

 

[sunchaser]

As I recall there are four possible switches/relays/solenoid that can activate the stop solenoid. Perhaps one is doing its job correctly? Don't forget power supply.

That said, Ski is the guy to hone in on the most likely culprit.

 

[High Wire]

Sure sounds like one of the trip switches is failed. Easy to check each with a dvm. The oil pressure switch needs to be checked with engine running or at least cranking. First get a wiring diagram.

 

[Ski in NC]

Oil pressure, coolant temp, exhaust temp switches are usually all in series so if any one opens, unit trips. For test purposes, disconnect op switch and jump the leads together. The temp switches can be tested with an ohm meter, should be closed. Also check for any blown fuses, tripped pushbutton breaker, loose leads in control box, fireboy unit in shutdown, remote switch can act up too. Anything further needs the schematic.

 

[sunchaser]

The toggle switch above the fuse should be in the up or run position.

 

[mike66]

If it's the kill switch, you can disconnect it and see what happens. I had a bad toggle on my 8.0 that I had to bypass, don't remember which one. Exact replacement from amazon using the number on the switch. 1/3 price of what Westerbeke wanted.

 

[nmuir]

Mine had the same symptoms and it was the stop switch on the panel - a momentary switch that was being not-so-momentary. May not be your problem but worth a quick check as it is fast & simple.
Good luck!

 

[Daddyo]

I've tried disconnecting the stop switch, bypassing the op switch and ohm confirmed the temp switch and still the same. There's no breaker on my unit that I can find. I've even moved the idle adjuster outward to shorten the distance on the throw for the magnet.

 

[High Wire]

OK, What year and model?

 

[bayview]

you still have to test the oil pressure and temp switches.

 

[tinped]

Not an expert by any means here,but just looking at this electrically.A momentary contact switch usually is installed to pull a contact in that is mechanically held.The safeties involved here(again no expert,refer to others)usually are in series,and would prevent the genny from starting at all,which appears not to be the situation.Look for the actually relay that the momentary switch applies to,after it passes thru the safeties.

 

[Daddyo]

1981 7.7kw. Here's the wiring diagram. Mine does not have the circuit breaker as per the diagram.

 

[Ski in NC]

Looks like the way this is wired the stop switches are in series and contacts on both are normally closed. So while off, all the stop switch terminals should be energized. Check that. To stop, either switch opens to take power off the oil pressure switch.

Right now, one terminal of the oil pr sw should be hot. Connect both leads together and it should make the fuel solenoid click.

 

[Ski in NC]

Also, are you sure this is a Perkins engine? With the rotary CAV pump? Or is it a Mitsubishi with in line injection pump?

Open circuit breaker should cause no start.

 

[tinped]

one possibility(happened to me) was the remote start.See if that can be disconnected.sometimes just a harness plug,and just work off the start/stop on the unit.This would eliminate a good chunk quickly,allowing you to concentrate on Ski's suggestions.

 

[TDunn]

Westerbeke generators are wired so that they shut down if oil pressure is below some threshold. I suspect that the oil pressure switch isn't working. Are you holding the pre-heat button in until you are showing oil pressure on the gauge? On mine if you let the preheat switch off before you have adequate oil pressure the engine stops.

 

[Ski in NC]

Mark- in my above post the stop switches I mention refer to the toggle switches. Stop should be hot on both terminals, both local and remote switch.

 

[Daddyo]

Thank you everyone for the suggestions. I'll be checking again when I'm back to the boat in a few days.