2001 225 Optimax has No Power to SmartCraft Gauges, Ignition or Trim Motor

[21 Outrage]

1. Engine Serial Number: 0T385093
2. Year/Make/Model: 2001/Mercury/Optimax
3. Prop you are Running: 17P MIRAGE Plus 15.5’
4. Current Maximum RPM: 5,750 RPM (theoretically and only if throttle held down and engine trimmed up)
5. Idle and WOT Water Pressure Readings: 2.0 PSI & TBD (will update, no H20 concerns)
6. Smartcraft or Analog Instruments?: Smartcraft (early version VDO Smart Tachometer and Speedometer)

Issue: Turning the key from OFF to START/RUN does nothing. My Smartcraft gauges don’t work, the starter and normal fuel pump noise don’t occur and I’m unable to trim the motor up or down. My 2 Batteries meet spec and are successfully powering all other accessories (e.g. Nav Lights, Bilge Pumps, Dome Light etc.). It seemed initially like it could be an ignition switch, neutral safety switch or kill switch issue so I started going in order before posting here and after striking out with a new ignition switch. If I recall correctly, my kill switch wouldn’t prevent trim or gauges but potentially only ignition or fuel but I’d really appreciate confirmation. I did measure good voltage at the large lug under the PCM on the starboard side but don’t know exactly where else would be best to check. I also checked the 3 20A and 1 15A fuses and they were fine; however, I was also seeing power to the top two (15A & 20A) which seemed strange. I’m praying that someone has seen this issue before and has some suggestions as to what to check or what is likely causing the non-starting issue.

Background: At the end of last season my engine wasn’t performing as it always had, the idle was across a broader rpm range and it was using about 40% more fuel. I performed required maintenance but also swapped a brand new port fuel rail, complete with new 3 fuel injectors and the two diaphragms while also replacing the starboard side tracker diaphragm. That didn’t change the performance, idle or fuel efficiency but did solve the issue where the engine revved up sometimes to 5,000 rpm on a cold start (before dying and restarting just fine). I believe it was the purple tracker diaphragm replacement (my old green version had a tear) is what fixed that initial cold start revving issue in case anyone else comes across a similar situation.

I was, and still am, planning on taking the boat to a local Mercury dealer to have it checked out and started taking a few quick videos to have available to help explain the situation. The other night I went down to the boat, after having successfully run the boat for a while and up to full throttle in the morning, and trimmed the motor down to get ready to start it and turned the key. Everything worked fine moments before this issue occurred (at the dock).

Work already done: New ignition switch, New Fuel lines from Tank to New Primer Bulb to New line to motor, rebuilt low pressure fuel pump via Mercury kit, 6 New IZFR5G spark plugs gapped at .032-.033" torqued to 20 lbs/ft (interestingly enough, the originally spec'd NGK plugs pzfr5f-11 run better but I'm trying to go with the latest recommendation). Always use Mercury DFI Oil and run marine Stabil and Quick Clean in every tank at fill-up. Last year, new compressor strainer, 2x new water outflow hose fittings that go down into the exhaust and were corroded).

Sidenote: When I unplugged the 3 pin connector red/green/blue from the throttle to the ignition switch and provided positive power to green/blue the motor successfully trimmed up/down (or reverse but as expected). I had a compressor seize up / sheer end cap bolts off and throw alternator belt at 800 hours but made it back to the dock in fog slowly and am now at 1,600 hours with the new updated compressor for a few years ago. Uploading Rough Idle Video from the same day the engine/gauges/trim stopped working:

[Savage]

I didnt read the novel, but was the Main Power Relay tested?

[EuropeanAM]

Remove and test the fuses inside the fuse holder (with an OHM meter). You may have a blown 20a fuse that provides power to the console/keyswitch/trim.

[21 Outrage]

Thank you very much Savage and Don, I can’t express enough how much I appreciate your help and sorry for the lengthy initial post. I tried swapping the main power relay with no luck. When I checked the top right 20A fuse, which had power going to it, it was in fact no good so I proactively replaced all 4 fuses with new ones and ensured I have several spares on the boat. I don’t know what blew the fuse and wasn’t able to turn the boat over as the batteries were too low so they’re charging and I’ll replace one tomorrow as a precaution regardless. Thank again SO MUCH!

[Savage]