Diesel generator starting issue

[motion30]

I have a problem in starting my westerbeke 8k diesel generator the procedure is to hold the glow plug switch on and after 10 or 15 seconds hit the starter switch. The motor starts but for the first 15 or 20 seconds and it runs really bad with not much RPM then it seems to straighten out and runs fine for as long as I care to run it also the power output is good this is a problem that just started a couple days ago and no work has recently been done on this unit
Looking for a direction of where I should start to look for the problem

 

[High Wire]

Is the solenoid pulled all the way over?
My 8BTD would occasionally start rough then I would blip the preheat switch and everything would run normally. Shortly thereafter the preheat relay failed completely.

 

[motion30]

High wire
That's the same model generator I own where is the preheat relay located on that model and what was the approximate cost
Thanks

 

[C lectric]

Don't know your m/c but it's possible also that one or more of the preheaters are not working.

Check the solenoid of course.

But also check that each heater is in fact drawing current AND that the current draw is roughly the same for each.
If one or more heaters or the wiring have failed then those cylinders are NOT being heated and must go through a bunch of compressions before developing enough heat to start working properly.

 

[Maerin]

Not all the Westerbeke's are fitted with these relays, I believe they started in late 90's. They use these as a pilot relay to power the fuel solenoid and as a hold-in relay.
I've had the same symptoms you're describing, replacing the relay pointed to took care of it, had the issue more than once with the relay. If the contacts in the relay become worn, the fuel solenoid doesn't get full voltage and the engine bogs until the relay contacts make good contact and the fuel solenoid pulls in fully.
They're inexpensive, and they DO NOT have to be OEM Westerbeke parts which would make them about 3X the cost. There are 2 of them in the control box mounted above the generator. I keep a couple of these in spare inventory. Available at any auto parts place.

Could be your problem. Also check the continuity in the 3 safety switches located above the start and preheat switches in the diagram, since any voltage drop through that circuit will create a similar problem. The ladder diagram is very helpful in troubleshooting.

 

[Roger Long]

Are you holding the glow plug switch down for 5 - 10 seconds after the unit starts?

The instructions for our new 7.6 Westerbeke specifically say to do this and it runs the way your describe if we don't. I don't count but continuing holding the glow plug switch down until it gives that initial roar and settles down. This is just about the time oil pressure reaches normal range, about 5 seconds.

This wouldn't explain the sudden change in starting but something may have changed in the engine that otherwise wouldn't be a problem.

 

[High Wire]

My gen is 1987 vintage. The preheat relay is next to the oil filter. Bought the replacement, Sierra 18-235800 replaces wb p/n 24639.

 

[meridian]

Google westerbeke generator service bulletin for the fix. It fixed the same b problem for me. It adds one additional wire.

 

[Ski in NC]

Is this the one where fuel solenoid linkage is out in the open and visible? If so does it retract fully on preheat? It should, and stay in position through preheat, cranking and start and run. Also can check glow plugs. Take leads off each gp and connect a jumper wire to 12v. Brush jumper on each gp terminal, should get a little sparking. Dead gp won't spark.