Electrical problems

[Rob Fisher]

Help. I have a 16' lund pike and a 50HP merc.
when I check voltage at my fishfinder before turning on the motor I have 12 volts
when I start the engine I have 8 volts at the fishfinder. (it needs 10volts min to operate)
also the trim gauge on the console reads up to the top of the dial past the up reading. When the boat is running and I open up the motor full speed & I corner hard to the right the trim gauge reads correctly and I see 10-12 volts at the fishfinder power port (I have a multimeter attached).
Any ideas what this could be?
thanks
rob.

[Thom]

Rob,

I may be reading this incorrectly, it really wasn't too clear to me what is happening here (how can you read 8 volts on a machine that won't turn on unless it has 10 volts?) but it sorts of hints a a loose plug in the wireing harness that is somehow getting moved around as the engine gets turned hard so that it has better contact. So I'd start either at the key switch or at the engine and I'd just trace back throug the whole harness looking for any loose wires, loose connectors, or corrosion anywhere. I think that is going to come up your prolem, I don't think its a component failure, just in need of some electrical maintainence.

Thom

[sgilbert]

Have you checked the water level in your battery(ies)? Could be that, corroded wire(s), plug making poor contact.

[Rob Fisher]

I have a multimeter on the power outlet where the fishfinder usually is. I read the meter to see the volts.
Before the motor is turned on it reads 12 volts (the same reading as at the battery) which I just replaced.
As soon as I turn the ignition key on the voltmter reads 8 volts and stays that way unless I turn to the right and then the volts read 12 again momentarily until I straighten up the wheel and then it reads 8v again.
Is this a grounding problem?

[Rob Fisher]

well today I got some of this fixed. I had the ffinder grounded on a screw under the console. I ran another wire from the neg terminal of the battery to the same screw and all worked well. Can someone explain to me how the grounding works on a boat.
Are all of the screws grounded usually?
Also I have a wire coming from the top of the motor to a psi dial at the console. There is a black wire running from the top of the motor to a psi dial and then a white wire that is not connected to anything coming out of the psi dial. Any ideas what this is
thanks
rob.

[iawright]

>> Are all of the screws grounded usually? <<

No. In fact, most will be isolated on an aluminium boat to reduce electrolysis. And didn't your sonar's instructions say to run direct to the battery through a fuse? Now you know why.

[Mumblerone]

iawright...that's quick a rig you got there to tow around.* No tiedowns?* Looks great; quite an effort?* *