Losing my mind on 99 Optimax 225

[wyatt_kimmy]

Alright guys, ive scoured this forum for months...checked everything i can check and i am stuck. Unfortunately i hit my serial number sticker with some brakleen and it all rubbed of and i cant find the number in any of the other locations. Its a 1999 i do know that.

Problem: MY engine is losing power at WOT. Not dying completely but "bucking" if you will. What doesn't make any sense is that i can fire it up fresh off the trailer and it idles perfect, runs perfect, launches out of the hole perfect. Sometimes i can ride for 30 minutes before it starts to buck and sometimes only 10-15 minutes. It seems to get worse the warmer the engine gets. By the time the engine is good an warm it actually struggles to get on plane sometimes.

What ive checked/replaced: Compression is good, fuel/air pressures are good as well as leakdown test, new plugs and wires, new low pressure pump, rebuilt diaphragm pump with OEM kit, cleaned VST (no trash to report), checked all diaphragms in fuel rails, run it on a portable tanks to rule out big tank/pickup tube, replaced all fuel line and used the special clamps that i cant pronounce/spell lol, did the spark test light and im sure there is something i am missing.

All of that and im still having the same problem. Its consuming me and i need yalls help! Let me know if there is something i am missing/any suggestions on what else it could be.

[Savage]

What are the air and fuel pressures as the problem is occurring?

Run the boat on a separate 6 gallon fuel tank.

[wyatt_kimmy]

I havent been able to check what the pressures are when its happening as it would be very difficult to do at 65 mph on the water. I guess if I got long pieces of fuel line I could try it in the driver's seat!

I've already run it on a portable tank with the same results.

[Savage]

You absolutely have to read pressures as the problem is occurring. It can be done, long hoses, or a helper, or both.

My gauges have hoses that make it to the console.

You could also setup a camera recording the gauges.

[wyatt_kimmy]

Hopefully gonna make it out there Thursday so i will try to set it up so I can get the reading while running WOT!

[stevechumo]

I have an exact same issue with my 2000 Optimax 225. It's been running good for months, then it recently started the issue of losing power after running for the first 15 minutes. After that, it still runs but is only limited to 3300 RPM.
I replaced all pulse fuel pump, high pressure fuel pump, low pressure fuel pump, fuel filters, spark plugs, and propeller hub. I also had all fuel and air injectors professionally cleaned, but the issue is still there. I got a new air compressor, so I don't think that's an issue. I read from other forum that it could be the TPI sensor. Maybe I'll keep chasing ghosts. Lol.

[wyatt_kimmy]

Work has been crazy so i havent gotten a chance to get to the lake but i will report back as soon as i do!

Glad to hear im not the only one! PM me if you figure soemthing out. i have also heard about the tps sensor. willing to try anything at this point!

[stevechumo]

I will probably just buy the TPI (not sure why they call it TPI but not TPS). Having a boat mechanic look at the boat right away isn't an option. I called up a few shops, and their earliest availability is 1 month away.