Westerbeke 7.2 tripping 20amp breaker

J

JBJ

Member
Jan 14, 2008
111
Solomons MD
Boat Info
370 EC 1999
Engines
Cummins 6.7 QSB 480 hp
I have a Westerbeke 7.2 gas genny. When I try to start it, it will trip the 20 amp breaker in about 5 seconds. When I press the preheat switch I do not hear the usual "click", it will crank briefly and then trip the breaker.
Any ideas?
 
Breakers operate on the principle of heat ( current induced) travelling thru a bi-metallic strip,held in place with a spring.
Breaker is on the genny or at your panel?
Breakers will trip anywhere from 80-150% of their rating.
Tripping condition is a good sign, in a way.
System is telling you there is a problem...............somewhere.
Could be anything from a loose connection to a frayed wire.
Can you access the breaker connections safely & do you feel comfortable doing this?


How old is the breaker?
 
Steve Craig said:
Breakers operate on the principle of heat ( current induced) travelling thru a bi-metallic strip,held in place with a spring.
Breaker is on the genny or at your panel?
Breakers will trip anywhere from 80-150% of their rating.
Tripping condition is a good sign, in a way.
System is telling you there is a problem...............somewhere.
Could be anything from a loose connection to a frayed wire.
Can you access the breaker connections safely & do you feel comfortable doing this?


How old is the breaker?
Click to expand...




I have replaced the breaker, it is on the genny near the 8 amp fuse. I checked the wires and so far I have not found any issues.
 
New breaker telling you the same story as the old one...........problem..........."somewhere". It's doing the job it was designed to do.
Is it a ground fault breaker? Any minor leak to ground can trip these, as designed.
You can identify it by seeing the white neutral terminated at the breaker with the load side conductors.
Keep looking. I know how frustrating electrical gremlins can be to find.
Don't fall into the trap home-owner's were in with fuses at home. Blown fuse was replaced repeatedly & then replaced with a larger fuse until it held.
 
Another spot to look is the starter for the genny. Bearing wear, insulation breakdown can also cause an increase in current needed to turn it over.
 
I replaced the breaker because it seemed weak, the button would only partially diengage. (I know that is not a good description).

I disconected the wire to the starter solenoid and it will still kick the breaker.
 
Solenoid control wires or the load wires?
It's generally a switch with one side fed from battery power. Solenoid activation closes an internal contact that allows battery voltage thru to the starter motor.
Something internal is up, just don't know until you tear it down.Can you get at it to remove it?
I would take it out & have it looked at. These are very easy to rebuild yet very dirty job to do.
 
I took off the solenoid control wire. If I turn the start switch to "ON", (not start), the breaker is fine, when I turn the start switch to "on" and the preheat switch to "on", then the breaker will kick.
 
I believe your last post has narrowed it down the pre-heat functions which include energizing the:

1) electric choke
2) fuel pump
3) fuel shutoff solenoid (base of carb)
4) electric governor (versus the mechanical governor)
5) safety bypass on the logic board

I believe a short in the first four could trip that circuit (also a broken pre-heat start switch). You could disconnect each of the four in turn and see if one is causing the breaker to trip. Post your results and if that isn't it, I will pull the wiring diagram for your model and take a look.

-John
 
I have the preheat switch out, it is suprisingly difficult to find a new on!
 
Steve Craig said:
JBJ,
John is your man.
Wiring diagram should get it narrowed down to the source.
Click to expand...

Steve,

Thank you for the kind words.

JBJ,

If I was to make a guess....the fuel pump or the fuel solenoid are the most likely suspects. Of the two, the fuel pump fails more often. In either case, put the pre-heat switch back in and disconnect the fuel pump (should be attached with spade terminal couplings). Hit the on switch and then the pre-heat to see if it still pops the breaker. If that still trips, disconnect the solenoid at the base of the carb (single wire) and try it again. It could be the switch ......but it doesn't fail that often.

-John
 
I appreciate everyones help!
I suspect the fuel pump also, the reason I was going to switch out the preheat switch was that 4 years ago I spent over $3,000 at Hartges when tey pulled out the generator and replaced most of the parts, including the fuel pump.
I am having great difficulty finding the switch (part #353649) A SeaRay dealer said that they could get it for me if I ordered 15 @ $15 apiece. They suggestd I call Carling who made the switch. It has no part number on it and Carling said that I should call SeaRay!:huh:
 
JBJ,
For the switch try:OEM Parts LLC. I'd send you the link but I'm not computer savvy yet.
Get the customer service staff on the phone & see what they might have.
I just ordered 7 new paddle switch covers to replace my weathered units. $ 1/each.
As I'm Canadian I had to call to place the order but they were more than helpful.
 
If you can PM me a photo of the switch, I can probably help you with finding it.

$3k to rebuild the generator? I knew there was more to this story.

-John
 
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