ghosts in the machine

[prybry]

It seems a ghost has taken over my 175 Mariner OB.

When I put the boat (19ft Starfire) in the water and run for approx. a half hour everything works fine... then when the battery regains full charge (from starting, and running the power trim) all my gauges start to go haywire... my tach starts running backwards, my voltmeter and water temp flip backwards against the stop pins...! What the h@ll is going on? If I run the power trim up and down a couple times (seems to drain the battery a little) everything goes back to normal. For a while... a few minutes later it does the same thing..?

It seems tied to the battery level... when voltage is down everything is fine... as soon as the battery is at full charge.. wham.

The motor keeps running fine throughout the whole process. Never misses a beat.

Anybody got a clue what this might be?

Another question: How long can you safely run an OB with a water pickup clamp on the driveway.?... I'm wondering if I can make the above problem occur on dryland rather than have to trouble shoot the thing in the water.

[Bass Cat]

Wow thats is crazy, Iv'e never heard of anything like that before. Sounds like a voltage problem to to. I sure someone on the board can help. As far as time on the hose, as long as it's pumping water run it till you neighbors get pissed and call the cops.

[heath brinkley]

then when you hear the sirens, kill the motor, turn off the water, and jump on the couch and act like you've been sleeping for the last two hours.

[CAP'N ROG]

check your grounds. the power trim draws high current and may make the ground contact b ite in a little more for a short period due to heat it cools down and you loose connection

[Raceman]

I think an outboard exorcist is indicated. Don't forget to keep the RPM's down if you're runnin' it on a flush attachment.

[O/B Dude]

Wow, thats a tough one but what came to mind as I read the post was the possibility of an ionized cable or power supply wire. Check the resistance on both neg and pos battery cables, and also the main power wire that runs to your dash. If you have the trim pump inside the boat, check the power wire that goes to that too, as well as the ground. I think I would also check the voltage regulator per the merc manual. Easy to do with an ohm meter.

Keep us posted.
OBD

[Airboater]

Check the main harness connector on the right side ,the pins may have some corrosion mine had a similar problem.