250 PRO XB only turning 5000 rpms, NEED HELP!!!

[Chunk]

Boat sat 8 months with the lower unit messed up before I could get another one. Installed rebuilt torquemaster with the 1.25” shaft, took it out for test run and everything was fine. Went out a few more times, didn’t run it wide open just run between 45 and 55 doing some fishing. Went to run wide open one day and it acted like it wanted to stop around 5000-5100 rpms, called a friend to ask him about it and he said let’s take it out and see. Put it in and it ran fine, hit between 5900-6000 rpms speed around 74. So I thought maybe just a fluke, maybe bad gas or something I didn’t know. Well it ran decent the next few trips but the other day I put in to fish tournament and it wouldn’t turn over 5000 rpms and when you get to 5000 it drops down to 4900 and you lose around 1 mph.

Checked gas for water, no visible water.
Replaced plugs with champion QL77CC gapped at .35.
Tightened all connections on batteries and cleaned connectors.
I run 93 octane in it, poured some sea foam in the 16 gallons of fuel that was in tank.
Took it out to see if it made a difference and no, reached 5000 rpms slowed just a tad and that’s all it will do. Checked to make sure nothing was behind hotfoot as well.
Comes out of hole perfect, idles good and runs good all the way till it hits 5000 rpm.
Prop stayed the same, lower unit I had on before had no problems. Boat would run 83 mph, turning 6000.
It is a 2002 mercury pro xb 250, Trophy plus 26 pitch. Serial # is OT430081
Im new to the forum, never posted anything on here so if I’m lacking info just let me know. Thanks


Any ideas????

[Gamblinman]

Check your fuel pressure at all RPM levels to see if it drops.

[Chunk]

10-4, would you happen to know what fuel pressure needs to be?

[Chunk]

Any answers?

[hookahawg]

Don't know if it would contribute to your particular issue but I believe the plugs for that model year should be gapped at .040".
Also, I wonder if you have some sort of fuel "restriction" showing up at the higher RPM's.
I had that same engine and when I took my injectors to have them serviced, I couldn't believe the amount of fluid that spewed out of them at 6k RPM's during flow testing!
Just my 2 cents, but I would suspect that any fuel starvation on that thirsty pig would be like trying to get on plane with power poles down...lol.
I rebuilt my pulse fuel pump and took my whole fuel system apart and cleaned every bowl and screen as well as changed every fuel line in the boat to ethanol resistant.
Motor ran like a beast after that.
Good luck.

[Melton Jason]

I had a similar issue with mine a few years ago and it was the stator. Not saying for sure that is the problem with yours but it fixed mine.