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Engine won't turn over, no power

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bengaltiger14

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I have a Mercruiser 5.0L MPI Bravo 3. This past Saturday, I killed my batteries while playing music all day. I got a jump and got the boat started. I noticed when I took off that the boat seemed to lack the normal power. About half way back to my destination, I noticed that the battery gauge was acting erratically (going up to 16V and then back down to 12/13V). As soon I got near to dock to pull the boat onto the trailer, the boat shutoff. I then had no power to ignition or dash switches. Boat won't turn over at all. Nothing happens at all when the ignition switch is turned. No low oil pressure alarms or anything. .

Purchased and installed a brand new battery. When key is in the 'OFF' position, I have voltage readings as follows: 11.25V at both sides of 50A circuit breaker, 11.25V at the red/purple wire at slave solenoid and 11.25V at the Orange wire on the alternator. 10.8V at the battery connection on ignition key switch.
In the 'RUN' position, I am reading around 2.25V at all locations mentioned above.

However, if I disconnect the red/purple and purple connector from the alternator, I read a full 12.6V at all of the locations mentioned above when switch is in 'OFF' and around 2.6V while in 'RUN'.

Swapped out the alternator and ignition switch. Problems still exist. Still reading 2.25V at 'B', 'I', and 'A' when switch is in RUN and reading 0V at B, I, A and S when in start.

One interesting thing to note. While in RUN and reading 2.25V at the key switch, I flipped the kill switch to the OFF position and the voltage spiked up to around 8.4V at B, I and A.

Thoughts or suggestions please?
 
in most cases the neg battery cable connection at the engine block. your voltage readings indicate the battery was not hooked up.
 
Thanks. I will try to trace the negative battery cable back to the engine block. Any idea which side of the engine the mounting stud would be? I'm not lazy but the reason I'm asking is that the engine bay in my Sea Ray is extremely tight so it is really a job just tracing wire.
 
i had similar problem this week, except i didn't run battery down. i launched boat put drive down,went to turn key it turned over a couple times and blank nothing, turn key no alarms,dash readings,clicks,nothing.it was getting dark so i took boat back home to work on it. it was a blown fuse on under dash terminal block but something had to cause it,after reading some of these threads i decided the starter had to be replaced, i got as far as disconecting starter wires they seemed ok, but i went ahead with some emery cloth & polished all wire terminals and reconnected, and i actually scared myself it started up so fast! so with this all i lost was my launching fee to start & a little time. so this is my story i hope it helps someone. the top of engine solenoid was ok.
 
i do want to add to my prior comments that i did put up with delayed starting clicks for sometime. when you go to start all you get is clicks then it starts eventually. so polish up those starter wires see if it saves cost of new one.
 
All the under dash fuses are good. I checked those with voltmeter. I will check and polish the starter wires although I've never experienced delayed starting clicks or anything of that nature. One thing that's weird to me is how the voltmeter pegged the 16V and back down prior to the boat shutting off. It seems that this could be the key to figuring out the problem. Thanks.
 
bengaltiger14 said:
All the under dash fuses are good. I checked those with voltmeter. I will check and polish the starter wires although I've never experienced delayed starting clicks or anything of that nature. One thing that's weird to me is how the voltmeter pegged the 16V and back down prior to the boat shutting off. It seems that this could be the key to figuring out the problem. Thanks.
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ok im back, i have had my share of electrical problems on my 94 bayliner cruiser this summer i may guess what your going thru for a fix. i would be out trolling or cruising full throttle and my dashboard gauges starts going nuts and just blackout but motor keeps running, then during week when your at work the battery mysteriously goes dead. well this turned out to be the electrical harness connector from the motor harness to dash connector which was located just inside the gunnel near the throttle control. i disconnected this, sprayed elecrical cleaner from auto store waited for that to dry then sprayed electrical lubricant on harness and reconnected with a zip tie and wow ! back to normal i hope this helps.
 
Go to the slave solenoid and short the 2 large lugs together, starter will spin if battery cable connections are good.If it dosent the battery, battery cables, battery casble ends, battery cable connections are bad. you saw 16+ volts because the battery was not connected to the wiring and the alt started to run wild.
 
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I have not shorted the 2 large lugs but I did run a wire from the battery positive the the large lug with the yellow/red wire attached. The engine did start to turn over when I did this. I also did this to the yellow/red wire at the ignition switch and it also turned the engine over.

I just remembered that when I opened the battery compartment after all this occurred, the negative cable on the battery was loose. I immediately tightened it down and now here we are.
 
looks like bt doctur solved your problem. but as mine was ,..it worked also. main idea here is its in the wiring, be clean,be tight. my connections at starter looked ok, but a nice emery cloth shine does wonders too, all the way to the battery. the harness connection in gunnel needed attention in my case as mentioned before. it is very weird to drive around with a dead dash and no power to vhf radio or bilge pump, windshield wipers, anything hooked up at dash. i once years ago cruising out in puget sound and boat went dead in water, what happend was the main wire cable to alternator broke off probably from vibration then used up all battery charge, i was lucky to just switch over to second battery to get me home last two miles before i saw broken wire.
 
No. When I mentioned that the battery negative was loose and that I reconnected it, that was immediately after the boat shut down. I tightened the connection immediately. I've tried everything mentioned thus far except for the harness connection.
 
Alright, using the jumper from the battery verifies the battery cable connections to pass atleast 200 amps. Now you follow the power.
from the starter it may go thru a 90A fuse block then the system power goes thru the circuit breaker thru the harness to the cannon plug(engine harness plug)
and up to the dash. Under the dash should be another harness plug, from there power goes to the ign switch.
The ground connection is also needed and thats connected to a stud at the stbd motor mount bolts .
 
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I did measure 10.8V at battery connection on the ignition switch while in OFF. I need to figure out why the voltage drop. The voltage reads 2.25 while in RUN and 0 in START. You mentioned in a previous response that these voltage readings are likely due to a bad battery ground connection?
 
you need 2 things to make an electric device work positive and negative connections.
Run a + jumper from the battery to the ign switch, test starting ,gauges, panel switches, etc. Report what works
Run a - wire from the battery to the neg buss connection under the dash, test starting ,gauges, panel switches, etc. Report what works
It might be better to use a spotlight with test clips. The spotlight will draw more current than a meter and will find a bad connection better.
Again, start at the battery with a neg connection and test the positives, then have a positive connection and test the negatives.
 
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Did a few things in limited time this afternoon. I did not have time to do everything I wanted to but here is what I was able to do and the results.
-Ran a + jumper from battery to the battery terminal on ignition switch. Turned key to RUN and low oil pressure alarm went off, radio worked and got 12.6V at the 'I' terminal at switch. I did not try start the engine because I drained the block last night due to a freeze and did not want to mess something else up; however, it likely would not have started because the fuel pump did not turn on when I turned the key. None of the panel switches worked either. Forgot to look at the gauges.

-Ran a - jumper from battery to a know good ground. Nothing new. All the same symptoms as before.
 
Ok, your missing the + connection someplace. go to the starter , remove and clean all the connections. Even though the battery cable supplied power to the starter ,you may not have power to the main system.power goes from there thru the circuit breaker and to the engine harness plug. Thru the harness to the dash and there should be another plug under the dash.unplug it ,and clean.
If still not enough power , unplug it again and insert the wires from a spotlight into the holes for the red and black thick wires. spotlight should light.
to work this problem backwards, install a light on the red wire under the dash and put it where you can see it.
use a jumper from the + battery to test the light, then go to the circuit breaker and touch both sides of the breaker screws.
If the light "lights up" on both screws your good thru the breaker and the problem is between there and the starter
If it dosent light up on either screw, the trouble is between the breaker and the dash
If it lights on only 1 screw, the breaker is bad
 
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Further the light tester... connect one end of the light to the ground terminal of the battery and leave it there. "Walk" the other lead of the light downstream, i.e., towards to key and back to the control lead on the starter solenoid. See where you "loose" power. Also walk that lead to the heavy lead to the solenoid and out towards the starter itself.
Put that lead on the engine block itself when trying to crank. If it lights up at all. bad ground. You might have to resort to a multimeter at some point in this process.

One other thing... What kind of terminal attachments do you have to your battery. The mechanic that did my engine swap some years ago changed over to use the screw posts on my battery(s) for the connection to the battery. These have proven problematic over the years ( I saw earlier negative posts about this but as someone with an EE degree and no reluctance to deal with electrical issues, I decided to run my own tests...) IF you MUST use the screw posts, ditch the thumbscrews, use regular nuts with lock washers NOT NYLOK nuts... I am changing back next spring to the "post" style connections and keeping a terminal cleaner brush on board. My previous boats which used the posts, rarely had any issues in season if I used the terminal cleaner brush on both the post and wire clamp connector at season's start. The chemically treated felt washers, tended to keep the posts cleaner. Even with S/S nuts and lock washers, I often have to give the screw type connections some mid season ( 7.5 months long) attention.
 
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Sorry but I wasn't able to do a light test as I did not have the proper equipment. All I was able to do today was:
- As a check, measure battery voltage with meter - 12.5V
- Measured battery voltage at key switch in OFF ~ 10V
- Measured the battery input to the starter - 12.5V
- Measured starter output to 50A breaker ~ 10V. Then measured the inputs and outputs at the breaker ~ 10V.
- Went back down to the starter and began just messing with the connections at the starter by hand. By messing I mean just trying to manipulate and rotate the connections by hand in case one was not making full contact. My engine compartment is so tight that I could not, without more time, take the connections off and clean but nevertheless, I was able to fiddle with them. After doing this, I went back to the breaker and measured measured battery voltage, 12.5V, at both the input and the output.
- Went to the key switch and measured 12.5 voltage there as well.
- Turned key to RUN and voltage dips to about 9.7V. Read ~ 9.7 at B, ACC and I. Still no gauges, oil pressure alarm or anything.
- Turned key to start and read 0V everywhere.
- Turned key back to OFF, measured 10V at breaker input and output.

I'm thinking there is something going on at the starter solenoid perhaps. Bad/dirty connection battery connection from starter to 50A breaker?
 
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No, that's my next step when I have a little more time to spare so I can get down there, disconnect and clean them up. Hopefully tomorrow. Just wanted to provide you all with an update.
 
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