Optimax 225 RPM/Power loss

[OldSouth]

2006 Optimax 225 Serial # 1B256176 400 hours pushing a 22 ft Mako bay boat. Bought the boat with 330 hours on it about a year ago. Ran good for the first 20-30 hours then started having an intermittent power loss where RPM would drop down 3-400 while running but then it would jump back up and run good for a few minutes. It finally got bad enough that I brought to the shop in Feb of this year and they cleaned the VST, changed the fuel filters and the water separator spin-on filter. Ran great for the next trip or two then back to the same thing. Took it to another more reputable mechanic in my area and they found the spark plugs needed to be changed and 2 of the wires had bad spots that were arcing out so they changed all plugs and the 2 bad wires and had me back running better than ever. I've put 5 hours since that was done a few weeks ago and at the end of my trip Saturday it started doing the same thing again. Frustrating to say the least . Now it's got a single beep every 3 seconds or so which it never had before. I'm going to take it back to the shop hopefully this week just wanted to see what you guys think. Sorry for being so long winded. Thanks for any help you can give

[Savage]

Need the faults read.

[OldSouth]

Need the faults read.

Thanks, yeah I forgot to mention I have the vessel view mobile and it showed an oil tank sensor fault but I honestly didn't have time to dig into it because we were trying to get back to the marina before dark. Mechanic should be able to pull the faults and check it out.

[Savage]

Need to check oil tank level first.
If the oil tank is full, then you need a new tank.

[OldSouth]

Ok. I'll check it. Would that explain the power/rpm loss as well? Thx

[Savage]

Possibly.

[OldSouth]

Ok just fired it up. No codes, no beeps but still has a miss. I’ve narrowed it down to the #6 cylinder by unplugging the coils one at a time and nothing changes when I unplug #6. Pulled the #6 plug (all new plugs 5 hours ago) and it looks a little dark and oily. Just for grins I swapped the #4 plug for the #6 plug and the miss is still in #6. What’s the best way to check the coil for spark without shocking the hell out of myself?

[EuropeanAM]

Timing Light clipped to the suspect cylinder's coil wire.

If you have spark... and a black/wet spark plug, it may be a broken REED.

[OldSouth]

Timing Light clipped to the suspect cylinder's coil wire.

If you have spark... and a black/wet spark plug, it may be a broken REED.

thanks for the info! I’m going to see if I can get a timing light and go from there.

[OldSouth]

Timing light says that the coil is firing. I checked them all just to make sure and they all have good spark. Tell me more about a broken reed

[Savage]

Swap the coil and pug wire to another cylinder and see if the problem follows.

[OldSouth]

Swap the coil and pug wire to another cylinder and see if the problem follows.

Do I still need to do that even though the timing light showed that it has good spark?

[Savage]

I would.......It only takes 2 minutes.

[OldSouth]

I would.......It only takes 2 minutes.

Good point. I’ll try that this afternoon when I get home. Thx

[OldSouth]

Timing Light clipped to the suspect cylinder's coil wire.

If you have spark... and a black/wet spark plug, it may be a broken REED.

I have a service manual but looking at your parts diagrams on your site helped me understand the assembly of the air intake, reed plate, etc. I'm going to try swapping that #6 coil for the #4 like savage said just to eliminate any doubt. If that doesn't lead to a bad coil, I'm going to pull it down and inspect the reeds. I read another thread where you explained the disassembly and I'm going to give it a shot. May need some help with the oil priming sequence after. I'll report back with some pics of what I find and I''ll order from you if necessary

[OldSouth]

So I swapped the coils, no change. Swapped the plug wires, no change. Swapped the plugs, no change. Going to bring it to my mechanic Thursday and let him check it out. He thinks it’s possibly the injector. He called me back after hours to check and see what I came up with. Great guy. I’ll report back what he comes up with for future reference. Thanks for the help

[lpugh]

Quite easy to swap the fuel injector as well, just be sure to lube the o-rings. Direct injector is a little more difficult and may need a resizing tool to reinstall

[OldSouth]

Got a call from the mechanic. Said I had a bad injector. Not sure if air or fuel injector. Bill is $900 so I’m assuming both. Break out another thousand Lol. You guys think that’s fair for changing an injector?

[angle iron]

Direct Injectors are pretty pricey.

[JOE54]

diag . and replace one lil stout to me