2005 225pro xs Rpm problems...Need help guys.

A friend and fishing partner has a 2005 tr21x Triton with a 2005 225pro xs that he is having issues with.
*As boat reaches 5000 rpms + it backs down to 4900 then goes back to 5000. It will not exceed 5000 rpms. You can feel it hit a "wall" so to speak. It ran fine last fall, exceeding 5600 rpms with ease. The only thing my friend did before we took it out this spring was change the fuel filter and added Mercury fuel conditioner/cleaner(quickleen?).
*The local Mercury dealer has run Engine tuner through the motor, changed the plugs(#6 was fouled more than the rest), replaced leaking injector o-rings,ran compression test, hooked up to computer, and had us swap out the coil drivers on the back of the motor. We have been to the River 3 times hoping his mechanic had figured it out. This is getting frustrating.
Would doing a diagnostic on the motor show possible problems at the 5000 rpm level? The Mechanic said he can't spot problems that occur at that range, only at low rpms?
Any suggestions guys? This boat hauled butt last year, but now we get 59mph at 5000 rpms!! http://www.bassboatcentral.com/smileys/sick.gif ser#1B160414 26p Tempest plus prop(medium load in boat)

This isn't much fun to do.... but will probably narrow down your difficulties.

Have him run a "cylinder misfire test" AT WIDE OPEN THROTTLE while running down the lake. Record the "RPM DROP" for each cyl.

Once you've done this, compare the RPM DROP amounts.... one of them may be "weaker" than the others.

Verify clean spark on that cyl... and if spark is fine, have him give me a call. I can probably point him in the right direction. http://www.bassboatcentral.com/smileys/wink.gif

Thanks Don. I passed the info on to my friend so he can speak with his dealer about it. The Dealer also said he was going to have to run it on the water to find the problem(like we knew all along, even after we made 3 trips to find out it wasn't fixed). He also suggested that it may have a broken reed. I am not sure of that though, my evinrude had a broken reed last year, but it didn't affect the rpm's as consistently as this optimax. It runs great except at 5000 rpms it hits a wall. My friend did change the fuel filter at the beginning of the season. Could a defective fuel filter cause an issue like this at that Rpm range?

A "clogged or restricted" fuel filter could possibly cause this...

Don't "completely" rule out reed issues. Since the Opti's only draft "air" through the reeds (fuel is injected directly into the combustion chamber)... they WILL run "reasonably" with a damaged reed. http://www.bassboatcentral.com/smileys/wink.gif

There are other possibilities... will be very interested to hear the results of the "Wide Open Throttle Cyl. Misfire Test". http://www.bassboatcentral.com/smileys/wink.gif

Couple of other suggestions:
-run it with a remote harness
-run it with a portable tank
-do a vacuum test on the on-board fuel system, it should not exceed 2"hg.
-have the dealer install the smartcom box to record the water test.....

Well, my friends ProXs is still not runnig properly. Mechanic changed crank position sensor and throttle position sensor, entire fuel rail and injection system....no change. Mercury told him to tear down the motor. He called today to say that 3 different cylinder wall(sleeves?) were twisted. Does this make any sense? Mercury is sending a dressed powerhead to replace this one. Keep in mind, this boat has less than 30hrs on it and has never been abused(I have put 10 hrs on it myself).

Do you happen to know if the "three sleeves" were on the same side?

If so.... temperature may have played a role. http://www.bassboatcentral.com/smileys/wink.gif

Don, I will check on that. So I guess twisted cylinder sleeves can occur?

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EuropeanAM &raquo;</TD></TR><TR><TD CLASS="quote">Do you happen to know if the "three sleeves" were on the same side?

If so.... temperature may have played a role. http://www.bassboatcentral.com/smileys/wink.gif

</TD></TR></TABLE>

Don,
I asked this once before, Have you had or know of many 225 PRO XS motors having this problem?

Any other way of knowing if a sleeve has turned without tearing down the motor?

JAZII

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JAZII &raquo;</TD></TR><TR><TD CLASS="quote">

Don,
I asked this once before, Have you had or know of many 225 PRO XS motors having this problem?

Any other way of knowing if a sleeve has turned without tearing down the motor?

JAZII</TD></TR></TABLE>

Yes, on RARE occassions it could happen.

The simplest method to determine if a "internal visual inspection" is necessary is to get the engine OUT ON THE WATER... with the Computer Diagnostic System (or perhaps the DDT) connected.

Run the engine at WOT, and perform a "Cylinder Misfire Test". Record the RPM "drop" for each cylinder as it is misfired.

Compare the readings. The RPM drop for each cylinder should be reasonably close. If one or more is susbstantially "less RPM drop"... further investigation may be in order (such as verification of spark to the cylinder, spark plug inspection, a leakdown test of the cylinder, and removal of the cylinder head for internal inspection of the cylinder(s).