Thread subject: Whaler Central - Boston Whaler Boat Information and Photos :: 1999 Mercury Optimax - stopped running yesterday - no alarm

Posted by bmwmotogreg on 10/17/16 - 4:46 AM
#1

A couple months ago, we had the boat in the shop due to alarms. Turned out to be fuses that had corrosion on them that were causing the alarms. Replaced fuse, no problems for several outings. Yesterday, we were out and had a great time. We were about 5 minutes into our return trip and the engine quite. No alarm, no warning. Would turn over but would not restart. Turned off the batteries, waited a few minutes, would not restart. Took the cover off while bobbing about, checked the fuses visually and it would not start. THEN I physically pulled the fuses out and put the same fuses back in and she started right up..... None of the fuses had obvious corrosion and I will be replacing all fuses this week. Any ideas? By the way, this engine has less than 100 hours on it. Not sure if the previous owner had the 100 hr service so that will also be one of my next steps. Any nuggets of knowledge would be appreciated.

Posted by brooks89 on 10/17/16 - 1:36 PM
#2

What horse power Optimax is it? How fast were you running when it quit?

Posted by bmwmotogreg on 10/17/16 - 2:59 PM
#3

brooks89 wrote:
What horse power Optimax is it? How fast were you running when it quit?


135hp
Not sure about RPMs but somewhere around 4000 if I were to guess. WOT is about 5200 on my engine. I typically go WOT to get on plane and then back off to 4000 or so. Appreciate your input and reply. Hoping that changing out the fuses is the solution but has me nervous about our next outing....

Posted by brooks89 on 10/18/16 - 3:43 PM
#4

100 hours on a 17 year old motor probably means it has sat idle for extremely long periods of time. You mention having the motor serviced a few months back, how long have you had it and have you had any other issues?

Assuming the engine is new to you, If you haven't already, make sure your fuel lines are in good repair, install new fuel filters, and make sure your spark plugs are correct. Mercury superseded the original platinum plug specification in favor of an irridium tip plug several years ago. Also check your batteries, switches, and cables to make sure everything is corrosion free and tightened securely. Changing those fuses can't hurt either. Opti's can behave funny when there's a ground issue caused by corrosion or a loose connection.

I had your same motor until recently when I upgraded to brand new 150 Mercury Four Stroke. The old 135 never left me stranded but the #1 piston head melted from detonation causing a loss of compression in the cylinder. I couldn't not see spending the money to rebuild cylinders on a 17 year old motor.

Posted by chawk25 on 10/18/16 - 5:31 PM
#5

I have the same motor on my 18' Outrage. I also think that fuel supply would be where I'd be looking at first. Are you running regular gas (ethanol)? If yes - don't! If your lines haven't been replaced since the motor was installed, they might be causing the problem. They are melting from ethanol. Check and replace your fuel line from the tank to the fuel filter/water separator. Replace the cartridge on the separator. Replace the fuel line and bulb from separator to the motor. You have another filter inside the motor by the fuel pump. Replace that. All this can be done with flat head screw driver and less than $100 in parts and it takes aprox.45 minutes.
I recently went thru the same procedure and also replaced the 1.5 inch fuel fill line that supplies fuel to tank. That pipe was totally disintegrated and large chunks of if were found inside the fuel tank. All due to ethanol. The new fuel lines are ethanol resistant but I still would run non-ethanol.