2010 Optimax 150 loss of power, vibrations.

[Wa$tedAweigh]

My 2010 Optimax 150 (only 156 hours!) has lost power through the powerband. Prior to, I could run approximately 5800 rpm at about 62mph. All at once, my top end is maxed at 5000-5100 rpm and top speed of only 48 mph and the loss of power is noticeable from sluggish plane to WOT. Appears to have a slight miss at idle and then vibrates horribly at 1100 rpm.

I have verified the reeds are all intact but replaced with carbon fiber since I had it open.
Fuel and Air lines are good and pressures are as expected at the rails.
Fuel and air injectors inspected and tested for functionality (not machine measured).
VST opened (very clean) with no deposits found.
Compression test good.

A spark test was done and I was told it was sufficient but is there another way to verify the coils and plug wires are truly good? I feel like the only thing left is electrical.

[aarchdale]

I used a in line spark checker to find which one of my coils was bad. most of them had a bright light and the bad one still had light but it was very faint. cheap and easy, find one at any parts store
https://www.harborfreight.com/90-in-...SABEgI5dPD_BwE

[JOE54]

timming light should work also

[Wa$tedAweigh]

Thanks guys! I picked up a spark test light this evening and will try it out as soon as I can. I also went ahead and ordered a single coil and I plug wire so I can try to isolate my issues.

[Wa$tedAweigh]

I replaced all plug wires just for good measure. Put the test light on all coil to plug links last night and all 6 were the same to me. Took the boat over to the lake to see if it helped and I still have the exact same issue of slow to plane and reduced top end of ~5100 rpm and 50 mph. Boat does seem to have an intermittent miss when in gear and idling at no-wake speeds.

[JOE54]

need cyl drop test preformed to isolate non function cyl

[TomP.]

Did you change spark plugs I have had new NGK`s bad right out of the box happened twice and they were OEM as they stood behind them.

[EuropeanAM]

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

Check belt tensioner with an inch-lbs torquewrench (set to 70 lbs/in). Should click BEFORE the tensioner reaches the end of it's travel. Also make sure tensioner bracket is not striking alternator bracket.

Might want to drop the gearcase and check to make sure the exhaust tuner is securely fastened to the bottom of the Adapter Plate (not loose or flopping around).

[Wa$tedAweigh]

Totally forgot the engine serial! 1B788229.

Update. Plugs changed again. New coil arrived and I put it in place of each coil with no change across the board... still same issue. Belt tensioner is set as you stated and is not striking the alternator. The exhaust tuner may take me some time to get to but I’ll put it on the to-do list.

[Wa$tedAweigh]

Update:
Local mechanic said to send injectors for cleaning to a place named Brucato. Came back with 5 bad air injectors and one questionable fuel injector. Ordered 5 new air injectors and installed. Just took it on the lake with practically NO CHANGE!!! It did feel like it had a better hole shot but overall top end was at 50 mph and 5100-5200 rpm WOT. Still no where near the 62mph and 5800 rpm I’ve hit before. I just don’t get it. No warnings, no fault codes, good air/fuel/water pressure, good compression, good spark, fresh gas, new plugs, new plug wires, prop reworked recently (24p Tempest Plus), trim verified as true, PTP at 3.5”, throttle cables verified to open all the way, I’m just out of ideas at this point.

[EuropeanAM]

If ALL basics check ok- drop the gearcase, reach up into the midsection and see if the tuner is still FIRMLY attached to the bottom of the adapter plate (you should NOT be able to move it at all with a long screwdriver).

Nylock nuts in the exhaust... wasn't such a bright idea.