Electrical problem??

[egldvrbags]

1995 Bayliner 2050 LS
4.3 LX SN 0F436164, Merc Alpha 1, Thunderbolt IV ignition
Wisconsin fresh water boating

Engine completely rebuilt by Merc shop this past winter, 20hrs on it since then. Engine runs and purrs like new, except....

On 3 occasions in past month (1 at 1500 rpm, 1 at 3000 rpm, and 1 at 3500 rpm), all cruising (ie, steady throttle), I've lost all electrical power and obviously the engine dies. The one at 3000 rpm "coughed" from what sounded like the carb when it happened, other 2 no strange engine noise.

After switching the key off and on once or twice, the power comes back and it restarts and runs normally.

When this happens, I have no power at all - blower, radio, etc that usually work even w/ ignition switch off.

I've checked the kill switch, all leads from the battery, leads on all the gages, and all other wires I can see. Nothing appears loose.

I noticed at the beginning of the season (and even last year before the rebuild) that occasionally the tach would jump up about 1000 rpm for a few seconds with the engine at constant throttle. The engine didn't change speed. I pulled the leads on the tach, cleaned, and reinstalled and it hasn't happened since about June, so I don't know if this is related.

Any ideas?? Bad ignition switch??

Thanks,

Dave

 

[egldvrbags]

Re: Electrical problem??

Any ideas???

 

[Wotknot]

Re: Electrical problem??

Just a SWAG, but I'd check the main wiring harness bullet connection for starters.

 

[achris]

Re: Electrical problem??

If you are running radios, blowers, etc off the engine harness, then I would be changing that immediately....

Engine electrics and electrics for the rest of the boat should only have the battery and main isolator in common.

Run a separate pair (read and black) from the isolator to a pair of terminal blocks and then run everything from there, lights, radios, blowers, bilge pumps, GPS etc....

Only run engine items off the engine harness, nothing else, except maybe an hour meter and fuel gauge... (My fuel flow meter even runs from the 'boat' electrics)

Without separating the systems it's difficult (read 'impossible') to know where to start looking....

Chris.............

 

[chiefalen]

Re: Electrical problem??

Check each and every ground. Clean the connection good and the bolt it grounds to also real good.

Than spray it with corrosion pro.

Also make sure your battery connection is tight. Cables good? Clean?

 

[egldvrbags]

Re: Electrical problem??

Check each and every ground. Clean the connection good and the bolt it grounds to also real good.

Than spray it with corrosion pro.

Also make sure your battery connection is tight. Cables good? Clean?

Thanks! All the battery cables appear in good shape and clean. They are tight at the battery, no corrosion.

Unfortunately, the power comes back before I can do any troubleshooting. I'll recheck the main wiring harness.

Is there a certain wire I should be looking at? ie, one in particular that if it was damaged/frayed, would kill the power on the entire boat? I figure the main ground can do this but it appears to be in good shape.

Thanks,
Dave

 

[Don S]

Re: Electrical problem??

All those battery cables have 2 ends. Do you have a batter selector switch?

 

[egldvrbags]

Re: Electrical problem??

If you are running radios, blowers, etc off the engine harness, then I would be changing that immediately....

Engine electrics and electrics for the rest of the boat should only have the battery and main isolator in common.

Run a separate pair (read and black) from the isolator to a pair of terminal blocks and then run everything from there, lights, radios, blowers, bilge pumps, GPS etc....

Only run engine items off the engine harness, nothing else, except maybe an hour meter and fuel gauge... (My fuel flow meter even runs from the 'boat' electrics)

Without separating the systems it's difficult (read 'impossible') to know where to start looking....

Chris.............

Thanks Chris,
It's a 1995 boat and I've had it for 4 years. I don't see any "added" wiring that's not original. So, as far as the radio, blower, lights, etc, I have no idea where their power comes through the harness or not as it appears the power routing comes as it did from the factory.

I normally don't even use the radio (just a simple dash model). The only additional electrical item I use is the blower.

I thought I read something a while ago about beginning to troubleshoot an electrical problem at the tach but can't find it. Am I dreaming???

Thanks for any additional help...

Dave

 

[Don S]

Re: Electrical problem??

Most of the Bayliners of that size and era, had power coming from the red/purple wire of the engine harness feed directly to the fuse panel at the helm, from there, power was taken from a 15 amp fuse to the ignition switch.
I would check the round 10 pin harness plug on the engine first. may need to expand the pins for the main power and ground if they are a little loose.

 

[egldvrbags]

Re: Electrical problem??

All those battery cables have 2 ends. Do you have a batter selector switch?

Don,
Thanks. No battery switch. I've checked both ends of the battery cables and have loosened/retightened each, no corrosion. I don't see any frays/damage on the cables that I can see.

If the problem didn't correct itself so quickly, I could do some troubleshooting. What bothers me the most is that it happened twice when the engine was 3000rpm+ and I know that's not good for the engine to quit abruptly...

Other than the battery cables, is there another particular wire that if damaged could cause complete electrial failure??

Thanks,
Dave

 

[egldvrbags]

Re: Electrical problem??

Run a separate pair (read and black) from the isolator to a pair of terminal blocks and then run everything from there, lights, radios, blowers, bilge pumps, GPS etc....

Chris.............

Where is the isolator and what does it look like? I assume it's between the battery and the harness.

Dave

 

[Don S]

Re: Electrical problem??

You probably don't have an islolator. If you don't have dual batteries or even a battery switch I wouldn't think there would even be a need for one.
You are having a problem getting power to your helm fuse panel.

 

[egldvrbags]

Re: Electrical problem??

Most of the Bayliners of that size and era, had power coming from the red/purple wire of the engine harness feed directly to the fuse panel at the helm, from there, power was taken from a 15 amp fuse to the ignition switch.
I would check the round 10 pin harness plug on the engine first. may need to expand the pins for the main power and ground if they are a little loose.

Thanks Don!
It appears as you suggested that power comes out of the harness to the helm fuse panel and branches from there to the ignition switch, gauges, accessories. I'll have a good look at the harness.

With the engine running, let's say that red/purple wire was then disconnected between the harness and the helm fuse panel, would the engine quit? I assume it would since the ignition switch wouldn't be powered.

I certainly wouldn't disconnect the wire w/ the engine running, but it would seem to duplicate my problem as the fuse panel wouldn't be powered and no gauges/accessories would work either.

Thanks,
Dave

 

[Don S]

Re: Electrical problem??

let's say that red/purple wire was then disconnected between the harness and the helm fuse panel, would the engine quit?

Absolutely it would stop. There would be no power to the ignition system.

 

[egldvrbags]

Re: Electrical problem??

Absolutely it would stop. There would be no power to the ignition system.

Don,
Agreed! I'll have a good look at that red/purple wire. Also, P. 4A-8 of the Merc manual outlines the positive current flow. I'll trace all those wires/connections up to the helm fuse panel & see what I find, especially at the harness. Thanks again to all the great help from everyone!!!!

Dave

 

[achris]

Re: Electrical problem??

Check the fuse itself and the terminals in the fuse holder. I've seen a couple of them with just enough corrosion on the ends to cause a problem. That could account for your problem.

Chris..........