mercruiser 3.0 audible alarm and ignition fuse issue

[CaliMercruiser3.0]

We have a 2005 Bayliner 175 with a mercruiser 3.0 and an alpha one drive. The motor is a new motor with less than 20 hours on it, and was installed by a reputable dealer/repair shop. While running the old motor for many years we never once heard the audible alarm system sound, and never had an issue with the motor turning itself off. While on the maiden voyages with this new motor the engine has shut itself off twice now, the audible alarm system sounded one of those times, and the 20amp ignition fuse has blown 4 times. The first time the engine died and we found out later the ignition fuse had also blown, the alarm did not sound. That time the boat had run fine for about 35 minutes at various rpm's and trim levels. Then while we were cruising across the lake at about 3000rpm it died with no obvious issues going on. The second time we were on the lake for about 2 hours running it at extended times in various rpm ranges and it was running like a top. After cruising for about half a mile at 3500rpm we pulled the throttle all the way back to the neutral position fairly quickly, and the audible alarm sounded immediately. The boat idled for about 5 seconds with the alarm sounding and then it died and we could actually hear the ignition fuse blow at the same time. We immediately checked all fluid levels and looked over the engine, and everything was in good shape and where it should be. We then replaced the ignition fuse, and after turning they key back on the buzzer sounded again and the ignition fuse blew again. We repeated this process two more times. On the fourth try the buzzer went off and the fuse didn't blow. The engine started right up and ran at idle just fine back to the boat dock. Checked everything again after home and the fluids and connections were all good, so we aren't sure where to go with this. After looking at the wiring diagram for our boat we know that our boat doesn't have the oil pressure switch, the water temp switch. or the gear lube level switch, so we have no clue why the buzzer sounded like it did, or why the ignition fuse blew 4 times.

 

[alldodge]

After looking at the wiring diagram for our boat we know that our boat doesn't have the oil pressure switch, the water temp switch. or the gear lube level switch,

Howdy
If this is actually true, it would be the first motor ever produced and a lot of years that didn't have them. Being a 2005 this is even more a case of having all those switches. This is the standard 3.0 wiring without TKS. Note section "C" these are the 3 switches

 

[CaliMercruiser3.0]

Hello, The boat does have the harness with all of the leads, but I don't think they are hooked up, and I don't think we have the switches equipped. I will take pictures and post them. We bought this new and have all of the owners manuals still. We have the same diagram. Would the switches cause what I described above?

 

[alldodge]

The switches cause the alarm to sound. If engine has shut down and oil pressure drops the alarm will sound, it will also sound if the temp gets to high or if the lube bottle is low. So if the motor shuts down and a few seconds after the alarm sounds, then this would be normal.

The alarm will not cause the 20 amp fuse to blow this is another issue.

 

[CaliMercruiser3.0]

The pictures of the boat. Now we never had a reason to look at this stuff for the first 11 years that we owned the boat, so I don't know if anything changed with the install of the new motor.

 

[CaliMercruiser3.0]

The switches cause the alarm to sound. If engine has shut down and oil pressure drops the alarm will sound, it will also sound if the temp gets to high or if the lube bottle is low. So if the motor shuts down and a few seconds after the alarm sounds, then this would be normal.

The alarm will not cause the 20 amp fuse to blow this is another issue.

With the new motor we got a new starter and a new carb, but the alternator is the original. Could it be the sensor senders going bad? Is a 12 year old alternator pushing its age limits?

We ran the boat a lot for the first 5 years we owned it. Took it out all california summer long on the lakes and the rivers, but never in the winters. Then it sat covered for 5 years. Spent roughly a year in the shop getting the new motor and interior replaced.

 

[alldodge]

If this was a 1975 boat I could agree, but being a 2005 things are missing. I see the oil pressure a water temp senders, and the lube bottle wires. The drive should be a Gen 2, so where is the lube bottle?

Someone removed things and maybe because they didn't want to reinstall, don't know. Sensor can go bad but none of the ones in the pics have anything to do with the alarm.

Wish you were near KY I would find some time to come look at it.

ALT's don't just go bad, and 12 years is nothing that should think of replacing one, unless something happened to it.

 

[CaliMercruiser3.0]

The top left picture is the bottom of the lube bottle that is mounted on the top of the engine. There are no wires coming out of the bottom of the bottle like I have seen on many diagrams online.

Copy on the alternator. It runs right where it should and keeps things charges. I just wasn't sure if they surge as they get older which might cause that fuse to blow. Didn't know if it was related to the alarm or not.

The only other wires connected to anything on the engine block are the slave soleniod, the circuit breaker, and the electric choke.

Yeah for the price we paid I wish we had someone close to look at it too. They state they put it back together as was. We bought it new and unwrapped it at the dealer. Never did anything to it but the dealer services and installing a radio, so I know we didn't remove those things. Were they included on all of these models?

 

[alldodge]

Were they included on all of these models?

I have never seen one without them being installed. Knowing what the image is I can see its a lube bottle, and has the switch but don't see any wires. This may be one for Fun Times to help. The other loose wires should be going to the other switches. So with none of the switches connected you could unplug the alarm because it will never let you know anything is wrong.

It could also be that the alarm is shorting out and blowing the 20 amp fuse, its powered thru the ignition circuit

 

[CaliMercruiser3.0]

This is exactly why we were so thrown off when we heard the alarm go off (engine shut off and ignition fuse blew while buzzing), and then found there were no switches actually hooked up. We are going to replace the last few parts that weren't replaced with the new motor and check all of the grounds and connections.

The only thing that was added to the boat while in the shop for the engine swap were some lights, a Perko switch, and a second battery. Beyond that we are running with the same electrical hookups in the boat that it ran solid with for many years.

 

[Fun Times]

On 3.0's the alarm system is an option to have even back in 05. The gear bottles don't come with an actual float switch with wires sticking out for the 3.0's nor did they have the oil and temp switches which if they did have the temp switch, we should have seen them in the photos above.

Question would be did you ever by chance hear a alarm sound when you first turn on the ignition key with either engine?

Sometimes you may hear an alarm when voltage is low or at first key up but not always.

Do you have a depth gauge up on the dash? Some depth gauges have an alarm too that may sound off as well.

Check all power and ground wires to be sure all is tight and clean. Double check the installation off all recent work done including looking for screws that may have touched / cut into some wires anywhere on the boat.

 

[alldodge]

On 3.0's the alarm system is an option to have even back in 05.

Its a good day, I learned something new today. Thanks FT