outboard attempts to start on battery contact! strange!

Hello folks,

new to boating period. My fuel gage wasnt working so i bought a new one and this is where it gets weird!

in steps what i did:

unhooked the old fuel gage
hooked up the new fuel gage
hooked up the battery
started the boat...gage still didnt work.
turned off the boat
unhooked the battery
moved wires around on the fuel gage
hooked up the battery
started the boat
gage still didnt work
turned off the boat but now a starter spinning sound was still coming from the motor when it was off. i let it go for a 5-6 seconds. unhooked the battery, the sound went away.
unhooked the battery
turned wires back around on the fuel gage to original attempt position
now when i make contact to the battery it sparks and it attemps to start the boat..without the key in or anything
unplugged the fuel gage completely
again on battery contact the motor attemps to start without the key in the ignition
tried hooking up the old fuel gage, still same issue.


whats going on here!? at this point i could care less about the fuel gage, the outboard starting on its own on battery contact has me scared.

p.s its a mariner 40hp...1996

please help.

Branko

Bad key switch or wiring harness problem (break, chafe, rubbed off insulation etc) would be my first couple of guesses.

Sounds like this set-up is totally new to you. If so, here are a "few truths" about a used boat/motor.

The boat/motor "wasn't perfect" - if it was it wouldn't have been for sale.

It was probably badly neglected for the last few (to many) years by it's previous owner - it was sold because the significant other griped enough about that "thing hogging the garage/drive/backyard that never gets used".

It probably has seen zero maintenance for a number of year if at all.

Most rigs were bought on easy payment term financing over dozens of months. They got used a fair bit the first year. By year three it was down to a couple of long weekends a year and then they started to sit.

Anyhow, enough of my rant.

Unless you bought this from a dealer that certified it had been gone over, provided paperwork and at least a minimal (90 day etc) warranty, you have to assume you need to "make this thing sea worthy".

If you don't know/have proof of when the water pump saw service, gear oil was changed, plugs were changed etc, all that should be looked at/worked on BEFORE you ever get this thing near water. You don't want to end up miles from the dock with a toasted motor.

Mice or other critters may have called "under the hood" HOME for the past few years - they may have munched/chewed. Outboards die young from "not being used/sitting", you almost never "wear them out" from over-use. Sitting is worse and requires "more maintenance" than if they are running all the time.

You do need to track down your power issue, but make sure the motor is "fit to run" before you get to far along.

Not knowing your mechanical skill level I don't even know exactly how to advise you. If you are comfortable, get a manual and start going over things. Otherwise, try and find someone who can "take a look" (but this isn't a good time - everyone want's their boats ready "yesterday" at this time of year).

Sounds like the ignition switch is sticking in the start position is the ignition switch in the off position when you connect the battery. Get a cheap volt meter and check voltage at the fuel guage with the key on. Do you have access to the fuel tank sending unit check for voltage with the key on using the ground wire on the sender if no voltage check using battery ground. The sender provides neg to the fuel guage.

2 or 4 cylinder and serial number will help when posting in the future. The fuel guage should have nothing to do with the starter the only common denominator is the ignition switch or wiring issues like galamb says. When messing with the ignition switch make sure everything is correct before you connect the battery. All it takes is a split second shorting the kill wire to battery pos to cook the switchbox.

the boat was fully serviced when purchased, plugs, carbs all that. Been out 7 times with it, this is clearly my fault playing with the fuel gage...that crossed wires step was a stupid brain fart, a lesson for future.

I'll get a marine mechanic to start with the ignition switch, thanks for your help fells and for advice on boating.

Hi Just wondering did you confirm this was the ignition switch as I'm having exactly the same problem with my Mercury 90hp 2stroke
Thanks

Murkila1 said:

Hi Just wondering did you confirm this was the ignition switch as I'm having exactly the same problem with my Mercury 90hp 2stroke
Thanks

Click to expand...

It's not uncommon to see the contacts on a starter solenoid fuse, such that they pass current all the time. You can check this by disconnecting the small wire off the solenoid that powers the solenoid coil. On most Mercs, that's a yellow wire. If the starter motor still engages when the battery cable is connected, the solenoid is bad.

Another thing you could do is (with the battery still unhooked), disconnect both large wires (battery +12V and the starter) from the solenoid.

Measure resistance across those 2 large connections on the solenoid, with a meter set on low-ohms scale (i.e., Rx1). If you get a dead-short (low resistance), the contacts are fused. If you get a high-resistance (open circuit) the contacts are open.

Third check: disconnect the "hot" wire to the starter, at the solenoid or starter whichever is convenient. Reconnect the battery and listen for a "click". This is the solenoid engaging and it shouldn't do that until the key is turned to START. With the key off, measure voltage-to-ground at the small terminal on the solenoid and if you find voltage there, the ign switch is probably bad. You can also turn the key and see if the solenoid clicks when it should.

You should only have to do 1 or 2 of those checks before you figure out what's bad.

HTH & let us know what you find..........ed

It was the solenoid which is annoying as it was only replaced a couple of weeks ago. When this happened yesterdY it also seems to have overcharged the battery. I've obviously replaced this but as I'm not sure how the battery is charged on my late 90s model, so would having the starter running constantly cause this or is it a separate issue? Many thanks for the help