I recently bought a used boat and my tachometer/speedometer was not working (stuck at 6000rpm). I understand that Tach damage can be caused by electrical transients disconnecting the battery with the engine running. I bring this up because it has happened once while the boat was running. I suddenly lost power, shutting down my fish finder, gas gauge, and caused a sputter in the motor. Battery terminals are not loose and battery switch was in the on postion. Everything returned to normal once I switched the battery to off and back on. What can cause my sudden power lost and how to fix? Is my Tach and speedometer gone and need replacement?
Sudden Power Lost
- Thread starter mouach381
- Start date
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Welcome to the World of Electrical problems 
I think you may have found your culprit though in the battery switch or along those lines by having a loose ground.
1st place I would start is cleaning and securing all the connections to the battery switch, then go back and do the same at the engine block and maybe inside the console. Once done I would then see how those gauges then work?
After a while though if you are not making a lot of progress on this issue I would fold and then get it to your local dealer to go through the issue and have them check all the connections and grounds
One can waste a lot of time being cheep and waste more time than actual dollars in the long run, and will then have a lot more confidence in the repair once getting the boat into the hands of the experts who know and can also pull any codes from the engine that may also give them some clues to what is actually happening that a reset of the entire system via the battery switch is correcting for some time now
I think you may have found your culprit though in the battery switch or along those lines by having a loose ground.
1st place I would start is cleaning and securing all the connections to the battery switch, then go back and do the same at the engine block and maybe inside the console. Once done I would then see how those gauges then work?
After a while though if you are not making a lot of progress on this issue I would fold and then get it to your local dealer to go through the issue and have them check all the connections and grounds
One can waste a lot of time being cheep and waste more time than actual dollars in the long run, and will then have a lot more confidence in the repair once getting the boat into the hands of the experts who know and can also pull any codes from the engine that may also give them some clues to what is actually happening that a reset of the entire system via the battery switch is correcting for some time now
BarryB
Contributing Member
- City
- Pembroke Pines
Agree with Dave. Not only check the connections, but many crimp connectors corrode from the inside where the wire is crimped. Get yourself a 12 volt test light (at any automotive parts store). The test light can be used to confirm power while moving cables back and forth while checking for loose/broken connections. To keep from putting large holes in the wiring insulation, attach a safety pin to the point of the test light and then poke through the insulation.
Thanks for the recommendations, will try it. I've got a Facia brand tachometer so I can send it in per their warranty to get it fix at a reasonable cost but it won't do me any good if I can't find my battery shut off issue because I'm afraid it'll just damage the tach again.
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Agreed, you need to find the root cause of the voltage spike issue and I suspect the battery switch (one of the few places) that voltage can actually go by a internal short from 12VDC to 24VDC. This would also explain why resetting it "appears" to correct the issue. I take mine out from time to time to make sure all the connections on the back side of that switch are clean and still snug. It is also a excellent place for the use of lock washers
I would also check the actual battery connection points to make sure on a wave they cannot touch? Some boats have batteries and the cables naturally, very close together and since most use a venting type of wet cell unit, excellent place and way to make a small bomb
My other concern would not be the Tach as much as what it could be doing to other more expensive parts like the engine ECU. This is why I NEVER jump start any computer controlled engine period The simple act of touching the jumper cables to the battery posts and that spark it can create can wipe one out big time
I would also check the actual battery connection points to make sure on a wave they cannot touch? Some boats have batteries and the cables naturally, very close together and since most use a venting type of wet cell unit, excellent place and way to make a small bomb
My other concern would not be the Tach as much as what it could be doing to other more expensive parts like the engine ECU. This is why I NEVER jump start any computer controlled engine period
The simple act of touching the jumper cables to the battery posts and that spark it can create can wipe one out big time You were right on Dave! I found one of the +battery cables loose and touching a stud on the back side of the battery switch. On the front side of the stud is the off position. I'm sending in the tach for service, but you've got me concern about the engine ECU. Should I get it checked out with a professional technician? Thanks for the help.
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
We got lucky with that guess, but reminds me of going to the Doctor and saying it hurts when I do this "then don't do that" aspect of repairs But I try and work on the KISS principle and this time it served us well. I had a feeling that when you advised us resetting the battery switch was impacting the reported problem that was the logical place to start looking
Also goes to to show (again) it does not take much to really throw a monkey wrench into the mix and make a Royal mess of things
As far as the ECU goes, it really only has 3 modes of operation.
I would though still take the time to go through all the connections back at the engine to ensure they are both clean (as you can see from this picture and the rust) and snug
That simple act may save you for having to get towed home and part of my inspection process. As you can see, it really does not take much to create electrical havoc and when you factor in that most engines now have a ECU and just how sensitive they are to voltages, why it is wise to ensure you have good batteries and clean connections and grounds
I know of more than one computer controlled engine that was running like crap (blowing smoke and missing) that the install of a new battery or correcting a ground corrected when others were dead set it needed one of those mythical "Tune Ups" no, it was just below the voltage threshold for the ECU to operate (control) the engine as designed / programmed to do
One last thing, since you did have this kind of issue, I personally would not "trust" any current error codes that may be stored in the engine ECU at this time. Trust me, more than one Tech has been thrown a curve ball or has advised somebody it needed X sensor replaced (only for the issue to reappear later on) due to a low or over voltage condition. So if due for a engine service soon or at the next one, I would add to the list "clear all engine codes" (if possible) so that if one does actually show up, at least it is a recent event and then worth spending time ($$$) investigating
As we say in the Computer World GIGO "Garbage in Garbage out" and very easy to fool an Engine ECU (which is a computer also) under the very same conditions for sure.
But I try and work on the KISS principle and this time it served us well. I had a feeling that when you advised us resetting the battery switch was impacting the reported problem that was the logical place to start looking Also goes to to show (again) it does not take much to really throw a monkey wrench into the mix and make a Royal mess of things
As far as the ECU goes, it really only has 3 modes of operation.
- Operates fine and the engine is running as designed over the entire power band.
- Dead and the engine simply does not even start or restart.
- Limp in mode (usually a low voltage condition like a defective battery causes such) and the engine runs very poor with no way to advance either the timing curve or injector pulses. This condition (programmed running mode) can also get engaged by the engine when (for example) it is receiving a signal that the oil tank is low and is used to prevent further engine damage, but still get you home or run for X amount of time or limited to X RPM.
I would though still take the time to go through all the connections back at the engine to ensure they are both clean (as you can see from this picture and the rust) and snug
That simple act may save you for having to get towed home and part of my inspection process. As you can see, it really does not take much to create electrical havoc and when you factor in that most engines now have a ECU and just how sensitive they are to voltages, why it is wise to ensure you have good batteries and clean connections and grounds
I know of more than one computer controlled engine that was running like crap (blowing smoke and missing) that the install of a new battery or correcting a ground corrected when others were dead set it needed one of those mythical "Tune Ups" no, it was just below the voltage threshold for the ECU to operate (control) the engine as designed / programmed to do
One last thing, since you did have this kind of issue, I personally would not "trust" any current error codes that may be stored in the engine ECU at this time. Trust me, more than one Tech has been thrown a curve ball or has advised somebody it needed X sensor replaced (only for the issue to reappear later on) due to a low or over voltage condition. So if due for a engine service soon or at the next one, I would add to the list "clear all engine codes" (if possible) so that if one does actually show up, at least it is a recent event and then worth spending time ($$$) investigating
As we say in the Computer World GIGO "Garbage in Garbage out" and very easy to fool an Engine ECU (which is a computer also) under the very same conditions for sure.
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Spring is here and some are unpaking thier boats for use now. So don't forget to check the connections to the back side of the Battery Switch (see above) it's overall condition including the wiring connections, and their present positions
Dave LeGear
Contributing Member
- City
- What's left of Pine Island
- State
- Florida
Don't forget to check those connection again this year! It may supprise you how how little of an problem can cause a lot of havoc!
Offshoreman
Recognized Leader Triumph 235 Forum
- City
- North Coast
- State
- CA
Annual maintenance absolutely needs to include wiring and battery connections!
Remove the terminal connections, brush them clean and reinstall. Also, dielectric grease is your friend where there is evidence of corrosion or moisture. And not just the battery. Fuses pulled and cleaned, a spot of dielectric grease, make sure all connections are good and tight.
And check the ground. Commonly overlooked, and usually the culprit when Gremlins appear.
A little now prevents alot later.
Remove the terminal connections, brush them clean and reinstall. Also, dielectric grease is your friend where there is evidence of corrosion or moisture. And not just the battery. Fuses pulled and cleaned, a spot of dielectric grease, make sure all connections are good and tight.
And check the ground. Commonly overlooked, and usually the culprit when Gremlins appear.
A little now prevents alot later.
