7.6BTD Blowing 8A Fuse Part 3 - Bad Diode?

[dtfeld]

The one near the peacock is the high temp switch. Off the top of my head, It is normally closed and will open if the coolant gets too hot. The other is the exhaust over temp, and will open if over heated. Both will kill the engine if too hot.

you can jumper both sets of wires together for troubleshooting.

The oil presdure switch is the two wire, and the oil pressure sender is the single wire.

 

[ZZ13]

I was going to try one thing on mine if I couldn’t figure out the failed shutdown switch. On my 8.0 the three shutdown switches (exhaust temp, oil pressure and coolant temp) are wired in series. So if any one of them fails it breaks the circuit and shuts down the generator. So I was going to jumper from the start of that three switch string, to the end of that three switch string. That would take all three switches and their wiring out of play. If it still shuts off then you have something else going on. Only other thing in my 8.0 schematic that would shut it down is a stuck open stop switch. Have you verified both your stop switches are closed when not depressed?

regarding the aux oil switch (the one with the skinnier black wires). On my 8.0 it’s not part of the run circuitry. You can ignore that one for your debug.

That’s about the extent of my knowledge.

 

[ttmott]

Just a curiosity - did you check the Fire Boy relay module? Maybe there are a couple of things going on. The below is a 7.6BTD with the Monoplex start module but wiring is just about identical. If that relay has failed or the two wires are not making continuity for some reason the generator will start as long as the preheat switch is held then shut down when released. That would be the two White with red stripe wires.

 

[HP12Sea]

Quick progress report (and I think some of this was said by others, so sorry if repeating).

Since they were in crummy spots to try to remove, I did not replace either Oil Pressure switch, yet. Jumping them which seemed to tell me they were ok, but I'm going to replace one of them at least just to be sure I didn't need to.

As someone mentioned, there are two.
1) PN 037323: Red Wires to it & on my gen it's farthest away from the block and the important one apparently. Normally Open, closes with pressure.
2) PN 011552: Black wires to it (not sold any longer that I can tell) & is the aux and seems to be unimportant. When speaking with the Westerbeke guy, he was tracing it in the schematic and said, yep, it's not your issue as it goes nowhere and showed me the attached section, showing it goes nowhere really, I guess. Normally closed.

Will head to boat after work to see what I can accomplish and report back anything fun/intersting.

Thanks again all,

J

 

[HP12Sea]

Just a curiosity - did you check the Fire Boy relay module? Maybe there are a couple of things going on. The below is a 7.6BTD with the Monoplex start module but wiring is just about identical. If that relay has failed or the two wires are not making continuity for some reason the generator will start as long as the preheat switch is held then shut down when released. That would be the two White with red stripe wires.
View attachment 110478

Thank you! I did check Fireboy and see the wires going to it that are gen related but, honestly, not sure what I am looking for.

I saw and tested which are hot, which goes back to which switch on the remote panel, etc. but that was about it. It's not a system I really understand (wires disappear and are hard to see with larger bundles, etc) but do understand what you are saying.

Going to do this Oil Pressure switch first and then maybe delve more deeply into the Fireboy relay box attached #57 is the gen.

Thank you again.

 

[ZZ13]

Quick progress report (and I think some of this was said by others, so sorry if repeating).

Since they were in crummy spots to try to remove, I did not replace either Oil Pressure switch, yet. Jumping them which seemed to tell me they were ok, but I'm going to replace one of them at least just to be sure I didn't need to.

As someone mentioned, there are two.
1) PN 037323: Red Wires to it & on my gen it's farthest away from the block and the important one apparently. Normally Open, closes with pressure.
2) PN 011552: Black wires to it (not sold any longer that I can tell) & is the aux and seems to be unimportant. When speaking with the Westerbeke guy, he was tracing it in the schematic and said, yep, it's not your issue as it goes nowhere and showed me the attached section, showing it goes nowhere really, I guess. Normally closed.

Will head to boat after work to see what I can accomplish and report back anything fun/intersting.

Thanks again all,

J

Yup, the 011552 was a special request by Sea Ray to have a generator fault signal tie into the System monitor.

My generator is a 2013 replacement for the factory original which died due to lack of maintenance by the previous owner. We bought it without that second oil pressure switch even installed. I only have the one shutdown switch 037323.

 

[HP12Sea]

Quick update.

Another piece of the puzzle. I removed the fuel shut off solenoid from the engine to see how that was behaving. With it out, the engine runs fine.

Start the generator and she keeps running and the fuel solenoid remains retracted as long as I keep the preheat down. Once I let go of the preheat the pin shoots out.

I unscrewed the fuel shut off solenoid and verified that’s what’s happening. Now I’m just not sure if it is a bad fuel solenoid or something electrical that I got backwards when troubleshooting originally.

I have a have a feeling that it’s related to the relays somehow.

Going to look at the relays more carefully now just to make sure I didn’t screw up that wiring because that’s really the only wiring I’ve undone.

As usual, any help is appreciated.

 

[dtfeld]

It sounds electrical still, but fuel shut off solenoids hav been know to stick in a partially open position.

 

[HP12Sea]

Edited - Solved, phew and favor about plug please.

As mentioned, my fuel shut off solenoid is turning off after releasing the preheat killing motor.

(Edit, not sure what fixed it for me since I did a few things this day but yes, the following is totally wrong--->) So (and you can see this from wiring diagram), the preheat energizes the solenoid and after the preheat released the solenoid gets its hold power from the alternator. Red wire from solenoid turns into two purple. One to box, one to alternator. Alternator took a dump and not sending 12v to solenoid.

Replace alternator. Ordered from Westerbeke.

Question, current set up has two wires w/female plugs to spade conns. You can see the opening will also accept a plug. Noticing the rust (no idea why soooo rusty) but I think a plug that fits there would help protect it.

Anyone know what plug that would be?

Thanks,

J

 

[ZZ13]

Three cheers for J!!! Well done.

 

[HP12Sea]

Also, I think I have 5 of the smaller diodes and one larger one (that's not the right one for my 7.6 BTD) if anyone needs. You can see I bought in bulk after my first attempt to fix, tons of 8 amp glass fuses too, LoL. Only needed one of them.

If you need/can't find one, lemme know, I can send to you.

J

 

[techmitch]

Solved, phew and favor about plug please.

As mentioned, my fuel shut off solenoid is turning off after releasing the preheat killing motor.

So (and you can see this from wiring diagram), the preheat energizes the solenoid and after the preheat released the solenoid gets its hold power from the alternator. Red wire from solenoid turns into two purple. One to box, one to alternator. Alternator took a dump and not sending 12v to solenoid.

Replace alternator. Ordered from Westerbeke.

Question, current set up has two wires w/female plugs to spade conns. You can see the opening will also accept a plug. Noticing the rust (no idea why soooo rusty) but I think a plug that fits there would help protect it.

Anyone know what plug that would be?

Thanks,

J

Here is a great resource for connectors. This link has 18 pages of 2 cavity connectors.
https://connectorexperts.com/c-1261628-connectors-2-cavities.html

 

[ttmott]

Solved, phew and favor about plug please.

As mentioned, my fuel shut off solenoid is turning off after releasing the preheat killing motor.

So (and you can see this from wiring diagram), the preheat energizes the solenoid and after the preheat released the solenoid gets its hold power from the alternator. Red wire from solenoid turns into two purple. One to box, one to alternator. Alternator took a dump and not sending 12v to solenoid.

Replace alternator. Ordered from Westerbeke.

Question, current set up has two wires w/female plugs to spade conns. You can see the opening will also accept a plug. Noticing the rust (no idea why soooo rusty) but I think a plug that fits there would help protect it.

Anyone know what plug that would be?

Thanks,

J

That's the field wire to the Alt. It doesn't provide power. However, if that spade connector is grounded it will trip a breaker or blow a fuse....

 

[HP12Sea]

That's the field wire to the Alt. It doesn't provide power. However, if that spade connector is grounded it will trip a breaker or blow a fuse....

Thanks.

Interesting. Why would the field wire go to power on the solenoid and the fuel pump?

 

[ttmott]

Thanks.

Interesting. Why would the field wire go to power on the solenoid and the fuel pump?

The field is the magnetic flux that enables the alternator to create power. As voltage is applied and varied to the field the alternator voltage/amperage output is proportionally varied and consequently properly charges the battery. These alternators have internal voltage regulators that provide that regulation. This wire provides battery + power TO that voltage regulator so it can operate the field. This connection does not output any voltage. The alternator will not produce power without powering up the regulator. The way Westerbeke wires the field is a safety feature as should one of the limits (oil pressure, temperature, etc) shut down the generator or the battery gets disconnected it removes power to the regulator and consequently the field so the alternator will not spike high voltage and destroy it's rectifier or other components.

 

[ttmott]

Additionally, some older alternators need to have the regulator (field) turned on and off with a key switch as they will constantly draw from the battery even if the alternator isn't operating. The newer regulators shut off when the alternator isn't being driven; those are sometimes called a "single wire alternator".

 

[HP12Sea]

That’s interesting. Always appreciate the explanations. I wonder then, how the fuel relay and fuel solenoid hold get power when the preheat switch is let go.

Because in the schematic the relay gets powered up, sends power to those two items and terminates at the alternator, therefore when the relay’s let go no power will be going to those two.

That’s how I see it, but definitely I’m missing something.

Terrible weather here in NY/NJ this weekend. Hope it’s better wherever you guys are.

 

[ttmott]

That’s interesting. Always appreciate the explanations. I wonder then, how the fuel relay and fuel solenoid hold get power when the preheat switch is let go.

Because in the schematic the relay gets powered up, sends power to those two items and terminates at the alternator, therefore when the relay’s let go no power will be going to those two.

That’s how I see it, but definitely I’m missing something.

Terrible weather here in NY/NJ this weekend. Hope it’s better wherever you guys are.

When oil pressure comes up at engine start and closes the oil pressure switch the battery +12V routes through the oil pressure switch and that path then keeps relay K2 closed instead of the preheat switch which then the relay contacts continue to feed the 12 volts to the fuel pump, fuel solenoid, and alternator field.