Chasing surging RPM issue in 2000 Optimax 225. Is there a tracker valve gasket?

[bigoilman]

Fuel Pressure 90psi. Air Pressure 80 psi. Both readings remain the same long after shutdown (air side loses about 5 psi after 10 minutes).

Symptom - Motor surges about 600rpm (3100 down to 2500 and back almost instantly).

What I've tried:
Fuel / Air pressure delta
New Plugs
Swapped Tracker valve from port motor (running fine) to strbd motor (no change and the problem didn't follow the part).
Sprayed carb cleaner around all connections and hoses to look for vacuum leaks (none found).

What I just observed: My fitting on my pressure gauge leaked a little gasoline as I was checking it and it ran down on the tracker valve cover and....bubbles! Would a leak around the base of the tracker valve housing have the same effect as a leaking tracker valve (seems to me that it would)?

What is supposed to be used to seal that housing? I saw no evidence of a gasket/sealant.

Thank,
Richard

1999 Mako 282
Port - 2006 Optimax 225 Ser. # 1B447039
Stbd - 2000 Optimax 225 Ser. # 0T054331

[EuropeanAM]

Yes, and the DIAPHRAGM (as well as a small o-ring over one port) are what seal the cover. If there are leaks around the cover- one or the other is leaking.

[bigoilman]

Thank you very much. Since the time I posted, I removed the Tracker again, cleaned the mating surface with some 2000 grit sandpaper then reinstalled and retested. Bubbles are gone. Won't know if it helped my surging issue until I run it again tomorrow. If the problem persists, where would you suggest I look next? In addition to the measures taken in my original post, I've also swapped fuel lines from one motor to the other with no change (fuel system consists of one tank into one water separator then branched to both motors).

Yes, and the DIAPHRAGM (as well as a small o-ring over one port) are what seal the cover. If there are leaks around the cover- one or the other is leaking.

[bigoilman]

Update: I'm leaning more toward a TPS issue. Still surged yesterday. Initially worse than before. Since I had a good "First Mate" with me, he worked that throttle back and forth rapidly for about 30 seconds and the RPM stabilized almost completely. Same on our return trip (but didn't require the throttle manipulation). Once we were back in the bayou and out of the Gulf, I actually opened her up and did a full throttle pull and it didn't hesitate at all. TPS issue, perhaps?

[EuropeanAM]

Quite possibly. TPS voltage sweep test (when acting up), and review of the Run History & Freeze Frame (Fault) History are what is normally used to diagnose TPS problems.

[bigoilman]

Updating (because I can't stand people who don't update their findings! LOL). New fuel lines throughout, cleaned the VST twice, and in the end it was a weak Pulse Pump. Rebuilt it and she now runs WOT (5200 RPM as propped). Thanks to everyone who gave me advice.

[Savage]

Updating (because I can't stand people who don't update their findings! LOL). New fuel lines throughout, cleaned the VST twice, and in the end it was a weak Pulse Pump. Rebuilt it and she now runs WOT (5200 RPM as propped). Thanks to everyone who gave me advice.

Now you can install a much SMALLER pitched prop.

[bigoilman]

Now you can install a much SMALLER pitched prop.

What would you recommend? These are 19P Mirage Plus.

[Savage]

17P

[bigoilman]

17P

Thanks. I haven't experimented with the props. Boat is heavy, heavy. What would you expect RPM to be?

[EuropeanAM]

About 5600 (Approximately)