4kw Westerbeke diesel generator start-up problem

I'm looking for some ideas on how to troubleshoot a start-up problem with the 4kw Westerbeke diesel generator in my 1987 Marine Trader. Here are the symptoms:

• Depress preheat switch: no problems.
• Depress engine start switch: generator fires up quickly, generator runs smoothly, needles are solid
• Release preheat switch: temperature and pressure needles vibrate so fast they are a blur, and engine dies within a minute or so
• Engine starts right up if sequence is repeated, and gives the same results.
• Engine seems happy as long as I am holding down preheat switch.
• I have experimented with different time intervals for holding down the preheat switch, but end result is the same.

the most obvious things are the sensors for overheat, no oil pressure or exhaust Riser temperature. Easy to jump in and see if that solves the problem. Also any plug in the harness that's loose could cause a problem

The preheat switch is energizing the fuel solenoid. When you release it, the fuel solenoid is no longer being energized which shuts down the engine. Check the connections to the solenoid.

In that era Westerbekes the preheat switch overrides the three sensors. Thus when the preheat switch is released the sensors come into play and can shut down the engine. If there were a bad sensor, or if a sensor were being triggered by something the shut down would likely be immediate.

The shuttering and the delay in shut down sounds more like fuel starvation and thus the fuel solenoid might be culprit. You can watch the fuel solenoid in action and see what happens. Generally these fail every few years on a Westerbeke. Replacement is easy.

When needles are going nuts and thing running, briefly unplug electric fuel pump and see if needles behave. Fuel pump could be shorting that would explain both symptoms.

Also check output on batt charging alternator, it could cause needle vibe if output is crazy.

See in another post that you are looking for parts, What is the problem?

Look for a chattering relay or solenoid. High resistance of sensor switch contacts in the circuit will drop the voltage to the coil. The coil drops out and circuit voltage returns and the cycle repeats over and over causing the fluttering indications. The challenge will be to narrow down to the problem component. If it were me, I would jump out each pressure/temp switch one at a time with an alligator clip jumper lead and try the start. Whatever bypassed switch allows a normal start should be the problem child.

kartracer said:

See in another post that you are looking for parts, What is the problem?

Click to expand...

Solenoid ... maybe. See replies from Bay Pelican and High Wire. I think they have the right idea. I just need to do some experimenting to narrow down the list of possibilities. A quick test tonight showed the solenoid was indeed shutting down the engine. The question now is whether the solenoid is bad, or whether the solenoid is getting bogus input from other connections. I'll try to do those tests next weekend (my job sure gets in the the way of boat projects).

I had a similar problem "stopping when not holding switch on" called Westerbe talked with tech, first thing he told me to try, make sure the pick tail for the remote starter switch was completely in an tight on the gen set. Problem solved !!!

Agree with the fuel solenoid conclusion. I found that I could work the solenoid back and forth after the failure and this would "bring it back to life" but this will not work forever. Trans Pacific in Vacaville, CA has good tech help and the replacement in stock. They ship the day they get the order. Not terribly pricey.

and the answer is...

The problem was the 2 connectors at the water temperature switch. They were loose, and so not making good electrical contact. As long as I held on the preheat switch, the temperature and pressure switches were bypassed, as Marty on Bay Pelican correctly pointed out. A friend of mine quickly zeroed-in on those loose connectors, tightened the female parts of the connectors, and then hooked them back up. The generator now runs like a champ.

Sure is nice when it turns out to be something simple and cheap to fix!