1999 150HP 2.5 DFI, OPTIMAX, no power

[windjinx]

Ok, been trying to chase down a problem with the the motor not running above 2800rpm. Long story short. Ran good at idle, sputtered and bogs down under load once it tries to go over 2800rpm. Checked the pressure on the fuel rails, good, Compression on cylinders all good, No alarms and no codes on the DDT at idle. Did discover one plug that appeared not to be firing. (It was clean compared to the others) Changed the coil for that cylinder went to test motor, now all of a sudden there is no power at all to the motor, gauges, fuel pump etc. Tilt trim works. Put back on DDT now it says no ECM. Battery voltage is good. Checked and replaced all the 20 amp fuses, replaced the Main Power relay, replaced the starter solenoid. Still no power. Borrowed a good ECM just to see if that was it, but it didn't solve the issue either, still no power.

Looking to see if anyone might have an idea on this. Have looked for loose connections and haven't been able to find any. All the grounds were recently cleaned of corrosion. Will be checking the keyed ignition switch next. Just wondering if there is something that I maybe over looking.

Serial Number: OG938539

[JOE54]

elect fuel pump run = no swap main power relay with trim relay

[EuropeanAM]

Keep track of which one was the MPR, though (mark it).

If you would, please be sure to review the Announcements at the top of the Forum, and provide the Required Info (serial number) when posting. Thanks!

[windjinx]

Ok added the serial number to the original post. Thanks for the heads up on that. I did replace two of the three relays with new ones. If looking at them the three relays, I replaced the first two from left to right If what I read is correct the first one on the 1999 motor is the MPR and the second and third ones are the tilt / trim. Correct?

[EuropeanAM]

I believe that's correct- simple way to tell is the UP trim relay has two BLUE or Blue w/white stripe wires, the DOWN trim relay has two Green or Green w/White Stripe wires (leaving the last one as the MPR).

[windjinx]

Agreed. That is what I saw when I looked at them. So like I stated in the original post, the new MPR did not resolve the no power issue. So I, assume it has to be an electrical issue between the keyed ignition switch and the MPR.

[EuropeanAM]

Have you unplugged the Cannon-Plug (keyswitch harness) connector, cleaned the MALE pins, reconnected, and strapped the connector in it's retainer?

[windjinx]

Ok, found an intermittent connection issue on the back of the sealed ignition key switch where it goes into the sealed plug. Now here's my next question does anyone know what the replacement part number is for it. My current ignition key switch has 10 wires coming out of the back of the sealed plug. Most everything that I have found thus far only have 6 wires. Don't want to assume that connecting the same color wires together for the six wire plug is the way to go. Again this is for a 1999 2.5L DFI 150hp Mercury Optimax XL serial Number 0G938539.

Ignition Plug.jpgIgnition Plug 2.jpg

[EuropeanAM]

Only 6 required. If you have two wires of the same color, they go TOGETHER at the connection to the new switch.

Example: Red and Red w/Purple Stripe go together.

Black w/Yellow stripes go together.

Solid Blacks go together.

Purple wires go together.

Now you have six.

[windjinx]

Thanks for the confirmation EuropeanAM.