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

[HP12Sea]

Thanks...

Question. Are we saying it's normal that the pronounced clicking should go on for as long as you hold the preheat switch down (20 seconds in my case to let things warm up) before starting?

That being said, I'll go back to boat later to try again and then take a video. Maybe my gen is good to go but the clicking made me question things as it used to be one discernible thud when preheat solenoid engaged and not this clicking.

Also, will still need to sort out why having the remote panel connected blows the 8 amp fuse when depressing preheat. Good times

 

[ttmott]

Thanks...

Question. Are we saying it's normal that the pronounced clicking should go on for as long as you hold the preheat switch down (20 seconds in my case to let things warm up) before starting?

That being said, I'll go back to boat later to try again and then take a video. Maybe my gen is good to go but the clicking made me question things as it used to be one discernible thud when preheat solenoid engaged and not this clicking.

Also, will still need to sort out why having the remote panel connected blows the 8 amp fuse when depressing preheat. Good times

Yes - normal. That continuous clicking from the fuel lift pump should go on as long as the preheat switch is depressed as well as all times the generator is running.

 

[HP12Sea]

Thanks again.

So tried to upload a 12 second vid but can't seem to do it. Will try some more stuff later and report back then.

Edit - OK this got me to get my old youtube account going.

Hope it works and does this sound OK?

https://youtu.be/SlqY_HPkN-U

 

[ZZ13]

Thanks...

Question. Are we saying it's normal that the pronounced clicking should go on for as long as you hold the preheat switch down (20 seconds in my case to let things warm up) before starting?

That being said, I'll go back to boat later to try again and then take a video. Maybe my gen is good to go but the clicking made me question things as it used to be one discernible thud when preheat solenoid engaged and not this clicking.

Also, will still need to sort out why having the remote panel connected blows the 8 amp fuse when depressing preheat. Good times

You do not hold the preheat down for 20 seconds BEFORE pushing the start button. You push and hold the preheat and then immediately start the generator. Then continue to hold the preheat for about 10 seconds while the generator runs enough to build oil pressure so that the oil pressure switch won’t cutoff the generator.

 

[dtfeld]

Thanks again.

So tried to upload a 12 second vid but can't seem to do it. Will try some more stuff later and report back then.

Edit - OK this got me to get my old youtube account going.

Hope it works and does this sound OK?

https://youtu.be/SlqY_HPkN-U

I hear the glow plug solenoid click and the fuel lift pump running (continuous clicking). That’s good!

 

[ttmott]

I hear the glow plug solenoid click and the fuel lift pump running (continuous clicking). That’s good!

I know exactly what the issue is.
It's painted white.... They fail every time they try to emulate an Onan.

 

[HP12Sea]

You do not hold the preheat down for 20 seconds BEFORE pushing the start button. You push and hold the preheat and then immediately start the generator. Then continue to hold the preheat for about 10 seconds while the generator runs enough to build oil pressure so that the oil pressure switch won’t cutoff the generator.

Where did you hear that? What I know there’s a sched of how long you do hold down preheat before starting and it’s based on temp. Attached is a procedure for my gennie that talks about holding down before starting.

 

[HP12Sea]

I hear the glow plug solenoid click and the fuel lift pump running (continuous clicking). That’s good!

Thanks. Tested and the electricity is going where it needs to (glow plugs, etc.). Turns over but doesn't start and while turning over, it also stops turning over for some reason. I only have a 7.5 amp fuse in there as don't have any 8's but it's blowing occasionally and doubt moving to the 8 will make a difference. Need to find out while blowing and know the other thread has some info which I'll study up on.

I also tested the diode I put in and it failed. So bought a bunch more and will replace that one and try again, probably this weekend.

Thanks again.

 

[ZZ13]

Where did you hear that? What I know there’s a sched of how long you do hold down preheat before starting and it’s based on temp. Attached is a procedure for my gennie that talks about holding down before starting.

Good question. Not sure where that came from. Either in my manual or the guy who installed the generator instructed me that way. I’ll double check. That’s how I’ve started mine for 8 years. But I retract my statement for yours based on your manual. I have 8.0 BTDA.

I just checked the online manual and it says to hold preheat for 10 seconds if above 41F. So I apologize for my bad recommendation. I guess I’ve had no issues starting since it’s usually pretty warm in my engine room where I live.

 

[dtfeld]

If you pull the glow plugs out and put a battery to one, it takes about 10-15 seconds for them to start glowing red.

Mine starts easily in the summer, but needs some preheat when it gets below 30 at night.

If you preheat before every start, you won’t damage the glow plugs, they are pretty robust, and easily replaced.

 

[dtfeld]

Thanks. Tested and the electricity is going where it needs to (glow plugs, etc.). Turns over but doesn't start and while turning over, it also stops turning over for some reason. I only have a 7.5 amp fuse in there as don't have any 8's but it's blowing occasionally and doubt moving to the 8 will make a difference. Need to find out while blowing and know the other thread has some info which I'll study up on.

I also tested the diode I put in and it failed. So bought a bunch more and will replace that one and try again, probably this weekend.

Thanks again.

If this engine turns over , it should start as long as it’s getting fuel. The electrical issue you describe will blow the fuse and prevent turning it over at all.

Make sure the diode is installed in the right direction. A diode is basically an electrical one way valve. In this application it allows a little current to flow to the start relay to simulate the oil pressure switch signal until the engine oil pressure, then removes that part of the signal once the preheat switch is released. The side with the band is connected to terminal #6, the unbanded to terminal #2. You can go back and look at my picture if that helps.

When I had this happen, I had the exhaust temp switch fail as well, so go back and check that, or just jumper it out of the circuit temporarily. It a Normally Closed switch, so you can put a small wire between the spade connectors for testing.

 

[HP12Sea]

Thanks again all. Did all I can do this week. Will try to tackle on Sat. Recent dev, tested diode and it's bad so ordered several more in eager anticipation of not needing them all but having them just in case. Already have a bunch of 8 amp fuses too.

Will report back.

 

[HP12Sea]

Update and made progress. I will also post more later with pics and more of what I did.

I replaced a few of the sensors/switches. The diode was also bad again so put in another new one. After doing all that and jumping the oil pressure switches, she starts and runs but when I let go of the preheat switch she died.

Now that she ran I put the wires back on to the oil pressure switches but oddly enough when I connect the last red wire on the OP switch the pump starts ticking as if the preheat switch is down. So somehow there’s current going through that oil pressure switch.

Not sure why she dies when I let go of the preheat and not sure why she clicks away when I connect that last red wire on the oil pressure switch.

Quick edit: When I disconnect remote panel the pump won’t go on when moving emergency start switch to run.

Thoughts are appreciated.

Thanks again, from the engine room.

 

[ZZ13]

Update and made progress. I will also post more later with pics and more of what I did.

I replaced a few of the sensors/switches. The diode was also bad again so put in another new one. After doing all that and jumping the oil pressure switches, she starts and runs but when I let go of the preheat switch she died.

Now that she ran I put the wires back on to the oil pressure switches but oddly enough when I connect the last red wire on the OP switch the pump starts ticking as if the preheat switch is down. So somehow there’s current going through that oil pressure switch.

Not sure why she dies when I let go of the preheat and not sure why she clicks away when I connect that last red wire on the oil pressure switch.

Quick edit: When I disconnect remote panel the pump won’t go on when moving emergency start switch to run.

Thoughts are appreciated.

Thanks again, from the engine room.

Did you try jumpering the high temp shutdown switch. That’s the most common one to go bad and what went bad on my generator.

There are two oil pressure switches. One is the low pressure shutdown switch and is normally closed. If it fails you need to override it by jumpering its two leads together. The other is the Low oil pressure sender to the system monitor. It is normally open when everything is working right. So don’t jumper it.

One more thing. The power runs serially through both the on generator stop switch and the remote panel start/run switch. With the remote panel switch off, that creates an open circuit. You have to have the remote panel plugged in and put the remote panel start/run switch in the run position for the generator to continue running when started from the on generator switches.

 

[ttmott]

Did you try jumpering the high temp shutdown switch. That’s the most common one to go bad and what went bad on my generator.

There are two oil pressure switches. One is the low pressure shutdown switch and is normally closed. If it fails you need to override it by jumpering its two leads together. The other is the Low oil pressure sender to the system monitor. It is normally open when everything is working right. So don’t jumper it.

"normally" in this case means engine running and oil pressure up and nominal right?
Different than how they would be purchased.

 

[ZZ13]

"normally" in this case means engine running and oil pressure up and nominal right?
Different than how they would be purchased.

Correct.

 

[HP12Sea]

Thanks. This remote panel doesn’t have an on off switch. Both panel and gen look same. I got excited when I read that though thinking how can I miss that. LoL.

Vid of what it sounds like attached.

Normally the switch just stays in the run position but now when it’s in the run position you can hear that pump kick on even though neither the preheat or start aren’t pressed. When it’s in the run position and the remote panel is not connected the pump will not come on.

If the pre-heat solenoid and pump came on when remote panel attached and switch in on position I would think there’s a fault in the remote panel causing it. But only the pump comes on and not the solenoid.

Thanks again.

 

[HP12Sea]

And here is how it acts when the remote panel isn’t attached. Just need it to keep running when I let go of the preheat. I guess I need to do some more research on the oil pressure switches as mentioned.

 

[ZZ13]

Thanks for that picture. That remote panel is exactly what is the on generator panel on my boat. My “remote start” panel inside the cabin is just two Carling switches. One for preheat and a single combined Carling for Start/Run/Stop. So I can see how I may be confusing you.

is your on generator start panel exactly the same as what’s in your picture? In other words, can you start the generator from anywhere else than your picture? If so, where and what does that look like?

 

[HP12Sea]

Yes exact same thanks. I replaced that high temp switch this morning.

I didn’t know the two oil switches act differently. In the wiring diagram one is labeled aux with black wires and and the other has red wires. Aux is closest to the block. With the wires off, neither lead from either switch has continuity. So maybe one is broken and needs replacing.

I have one replacement switch which doesn’t have continuity between the tabs either. Will see what I can do.
Thanks again

Edit: Just jumped each oil pressure switch separately and started the generator up each time. But both times generator died when I let go of the pre-heat.

Pics of both switches I replaced. Is there another one I should look at?