Someone smarter than me can provide better details, but the outboard engine is the same - except for the engine drive shaft. Wont, fit, not interchangeable engines on the sport-jet for this reason.
Check these posts... had the no spark twice, once a crank sensor & once a relay.
I think last link has some good references too. Take a really good look at the relay, tiny burn marks at the pins.
Good luck!
2004 Mercury M2 jet boat, No Start/No Spark
Mercury 240 EFI M2: Only cranks once -...
check the crank position sensor, mine was intermittent for a while. Easy 2-pin connector under the flywheel. See thread: 2004 Mercury M2 jet boat, No Start/No Spark
I think the best advice is not to mix oils...i personally waited until the oil was low, then filled up with Pennzoil TCW3. Around $13-17 at walmart. After following this site for years, i believe this is the best advice. Whatever you do, ensure the product states TC-W3.
It is actually quite simple. the two wires are connected to a coil, the spinner on the sensor has small magnets imbedded into it. As the water spins the wheel, the magnets pass across the coil inducing a small voltage/frequency proportional to speed. Your indicator simply translates this...
I replaced my Speedo with a Faria years ago, works fine. Slight connection differences. Here is a pic i took, perhaps it may help.
You can check the pickup by measuring a small voltage pulse when you spin it, theres not much to fail on that - magnet & pickup.
The fish finder voltage alarm I have set to 11.7 V... an arbitrary value, not based on any experimentation. I do get the alarm during starting (this is expected).
I have the same boat, one good "car" battery i bought ~ 2 years ago ( ~$100) at autozone. Never have any issues, i run the radio & fish finder all day fishing or floating. Ive even dug the nose in, filled the boat with water & had the bilge pump run > an hour with no issues.
The radio and fish...
this is my current setup. My hook xducer is just foward of the starboard drain plug - the speed sensor wires are a good reference.
I have an elite 4 xducer in the bilge pump area - recently move from the starboard side of the grate (i was hoping new placement helped, but the xducer failed, it...
I've had good results with my Lowrance Elite x-ducer for ~8 years (the x-ducer finally died this year) RTV'd on the starboard side of engine, in the well where the "drain hose" lies.
I got a new Lowrance Hook, with Chirp & down/sidescan this year. That one I RTV'd just forward of the starboard...
I've gone through 3 "solid state" bilge pumps - the float switch is electronic. Same thing with those. This year i went back to mechanical float switch for that reason.