Mercury 90HP outboard will not restart after shut down

[Todd Maiorano]

I have a 1998 90HP Mercury Outboard ( sorry, i will have to confirm model type at home if needed).
I am having an electrical issue where after using the motor for a short period and then shut down, I can not restart the motor for 5 min or so. There is absolutely no power getting to motor or trim. When I try to restart, I hear my throttle beep, bit I get nothing from the motor. The trim controls on the throttle and on the motor do nothing as well. Not sure if it is a coincidence, but if I disconnect the battery cable and reconnect, the power comes back. Could there be some kind of relay going bad? Need help troubleshooting...any advice is appreciated.

Thanks,
Todd Maiorano

 

[Kevin W]

Re: Mercury 90HP outboard will not restart after shut down

Just a guess is a bad battery connection.
check the battery with a voltmeter and then check th battery cables where they connect to the motor when it is failing.

 

[Todd Maiorano]

Re: Mercury 90HP outboard will not restart after shut down

Just a guess is a bad battery connection.
check the battery with a voltmeter and then check th battery cables where they connect to the motor when it is failing.

I will try that as a first step. I cranked hard down on the terminals to make sure there was good contact, there is good juice in the batteries and there is no corrosion. All new cables this year too. All other electronics are working at this time too. I thought there was a short somewhere or a bad relay of some sort.

 

[Deep_Blue]

Re: Mercury 90HP outboard will not restart after shut down

You may not see much of a voltage drop unless something is drawing current, put a VOA across the battery and then turn on the lights, run the trim and what ever else you can to draw it down and that marine battery (if fully changed) shouldn’t drop below 10 volts. And when you turn off the lights and stop the trim that battery should instantly go back up to 12-14 volts.
You could also even recreate the symptoms and watch the voltage of the battery, do it a second time and watch the voltage from the starter to ground. If you find a difference between the battery test and the starter test then the only thing it could be is a solenoid.

 

[Todd Maiorano]

Re: Mercury 90HP outboard will not restart after shut down

OK, going out fishing tomorrow and bringing my OHMETER. I am sure the problem will surface again. I found my model # and serial #

Model 1997 90ELPTO
Serial 0G450523

I opened the top compartment and see where the main power cable goes to a solenoid. Is this the solenoid that is questionable or are there multiple solenoids that could go bad?
Thanks

 

[Texasmark]

Re: Mercury 90HP outboard will not restart after shut down

Does the other side of the solenoid go to the starter? If so it is the starting solenoid. The inlet side of the solenoid is also a "junction box" where battery power is supplied to the rest of the engine.

I just looked in the service manual and there isn's but one solenoid and it is for starting unless you have power trim then there is an UP and a DOWN relay.

Removing and reinstalling power tells me you are resetting something electrical that has "brains". Other than the voltage regulator, there is nothing in the wiring diagram with brains.

A quick test you might make is to take about a 14 ga wire and connect one end to 12v at the batt term and the other to the small starting solenoid terminal where the yel/red wire is connected.

If your starter spins when you "energize" this solenoid, you have problems in your remote control/strart switch, or the connector/wiring that goes to it. May be a bad switch or "dirty" terminals under the dash. The remote control has to be in N to start and has an internal switch for determining that position. That switch may be bad or bad wiring.

HTH

Mark