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Electrical issues

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loic

New member
"Hi guys,
We've started t

"Hi guys,
We've started to have an annoying electrical issue with the Mercury. First thing - the engine wouldn't electrically start. Sometimes the starter motor would stick, but I don't think it was the issue this time as it would free up after a couple of tries. We lowered the engine, then pull started it as we had to get out the way of the launch slip, and we figured the batteries might just be a little dead.
Whilst it was running, the control box was giving out little, regular chirps which we were unsure about. These stopped after a little while.

We never got the engine to crank over with the starter, and when we got back to the slip, we were unable to lift the engine - I think the relays were engaging when we pressed the buttons, but nothing was happening.
I had to unplug one of the batteries and the hydraulic motor wires and connect it directly to the battery where it worked fine.

We've charged the batteries, and it still won't crank, so I don't think it's a case of having two flat batteries. The fuse is fine, but we've replaced it anyway.
Any ideas where to go from here? It's a curious problem as the engine was working fine last time we used it. Also, the fact that the hydraulic pump worked fine when plugged directly into the battery suggests there was plenty of power in there.

As always, thanks for your help in advance.
This is the engine:
http://www.frenchgeek.com/imageslg/boatlg4.JPG
http://www.frenchgeek.com/imageslg/boatlg7.JPG

-Loic"
 
clean all battery connections/

clean all battery connections/ check voltage of batteries with a meter. check 20amp fuse at powerhead
 
Also make sure your getting a

Also make sure your getting a good ground. Put meter on the hot wire from battery at solenoid and ground to engine. If voltage drops significantly when you turn the key you have a bad ground somewhere
 
"i had the same problem i was

"i had the same problem i was useing a car battery
shame on me but once i got the correct cranking amps on a good marine battery it all vanished and starts no worrys"
 
"Hi all,
I've been doing

"Hi all,
I've been doing some testing with a multimeter and have come up with some interEsting results. I'm not 100% sure what to make of them, so was hoping you might be able to let me know what you think:

First off, the voltage from the batteries is a healtHy 12.8V - the batteries go to two rails from which the boat's electrics are fed. From these rails, the power cables go to the outboard. Interestingly, when I disconnect either the negative on the starter or positive from the solenoid, I only get a maximum of 11.5V across them, so somewHere between the rails and the outboard it's dropping a whole volt. I'd have thought the outboard trim, etc would still work though, even with this drop in voltage.

It gets more interesting, however, when I connect up the solenoid and the starter - the voltage I read across the two then drops to something like 1.5V. It climbs a little to maybe 3.5V when I turn the ignition off. Presumably this suggests a bad earth? I've taken as many of the contacts I can reach apart and cleaned them, but it hasn't helped so far. I also disconnected the control box, and this made little difference, so I guess I can assume that it is working OK.

So at this stage, I guess I have a couple of options: disconnect the boat's electrical devices (eg VHF, GPS) to see if it's one of them that's making the voltage drop to below 12V, then once I've got 12V arriving at the starter/solenoid, I've got to find what could be making the voltage drop there (presumably, if it's working correctly, I should be seeing 12.8V between the starter and solenoid?).

Does anyone have a wiring diagram for this engine at all? It would really make life a lot easier is it came to isolating the bad earth.

As always, many thanks in advance."
 
If you disconnected the ground

If you disconnected the ground from the starter it will cause what your describing. The ground and 12v from battery should both go to the motor( ground to starter and 12v to solenoid). If your feeding a 12v panel it should be with a separate wire feed from the battery to that terminal.
 
"Hi guys, OK, got it sorted!

"Hi guys, OK, got it sorted!

It was one of the chunky cables gloing from the battery - the contacts were all fine, but there was a drop in voltage through it, so it must have deteriorated internally. I plugged the battery straight into the engine with different cables, and everything kicked into life.

Thanks so much for your help!"
 
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