2006 250 Optimax XS surging at higher RPM

[RobFess]

2006 250 Optimax XS
Serial # 1E001433
Cold compression 118-122 and 125 on cylinder #4
Rigged on 2006 Champion 210 Elite with 10in Atlas and 25 A45 Tempest

Bought boat in December and been redoing it. Finally got to take it out a couple weeks ago. First trip, boat would only get to 4000ish RPM and surge in and out especially if I pushed to WOT but would not go above 4300. Went home and replaced fuel filter. Pulled plugs (all looked great) it does have the spec plugs IZFR6J (NGK) didn't notice any wetness, cracks, or any other signs of fouling. Compression looked good. Gray fuel line has been replaced with a blue line(MARPAC 7-6901) from tank to VST. Siphoned gas from tank as I wasn't sure how long it had been sitting prior to me purchasing it and put in 20gal of 91. Lake tested again. Starts great. Idles great. Gets up and out of the hole great. Climbs quickly to 4500RPM, raise trim and JP and get it to 5300 (about 65mph) and power cuts out and drops nose hard (like slamming on brakes) then proceeds to cut in and out in that 4000-4500 range. Lay it down, kill motor for 5-10 minutes. Startup and try again with same result right at 5000rpm. Performed this multiple times with same outcome.

Plan on checking fuel/air pressure today. Will also try running another tank to eliminate issues from bulb back to tank in case fuel line has collapsed. One thing I saw in a previous post was electrical (battery) issue. The boat only has a Group 27 with 750MCA. I only had one graph on the boat LCX-113CHD for mapping and GPS. I have a 31 AGM Odyssey in my 196 I thought to throw in there to test and see if that could be part of the problem? Don't want to try and fix too much at once without lake testing after each fix to isolate problem. Dr. Don, hopefully you have some insight on this particular motor.

[JOE54]

be very careful with this engine it sounds lean would defiantly find a source of problem or risk powerhead failure , fuel psi test is in order for sure

[EuropeanAM]

+1

I would want to look at the Full Printouts and verify that it's not in Guardian for some reason.

Would then want to put dual-pressure gauges on it: Low pressure fuel port AND high pressure fuel port.

Have another person video the gauges while you run the boat on the water (gauges strapped to front of motor).

This info will be very helpful, more than likely.

[RobFess]

What should fuel/air pressure be for the optimax xs is it the 80/90 or the 94/109?

[JOE54]

94/109 real close gages differ sometimes

[EuropeanAM]

Just keep in mind we're watching BOTH fuel pressures (not air) for this purpose.

[RobFess]

Update: Have not been able to check fuel and air pressures. Did find my fuel line liner had collapsed as well as the line being pinched under the fuel tank from PO. Was worried plugs may have leaned out so replaced plugs and gapped to spec. Boat runs like a top. Idles great, no power loss under load, pops up on pad but am only seeing 5500 RPM at WOT. Boat is a 2006 Champion 210 Elite with the above referenced motor. Turning a 25 A45 Tempest seems it should turn more RPM. Only seeing 67mph GPS running light with 2 people. Thoughts? Should I still try checking fuel/air pressures?

[JOE54]

would look at linkages and setup verify full throttle , sounds real close to me might tweek engine heighth a tad ,,,,,, run it one person if it gets any where around 70 your done

[RobFess]

Verified I'm getting WOT at throttle body. I have run it light and alone and still only see 67mph and 5500 rpm. Has 10inch atlas Hydraulic jackplate and can pick it up or put it down with no difference at wot. I know this motor should turn a 25p much faster than 5500

[apdriver]

What are you getting RPM’s from? Analog or Smartcraft? Maybe I missed it.

[RobFess]

Analog. And I have wondered if it's accurate. It seems to be at least based on idle.

[JOE54]

get a vessel view and find out , its getting hot and humid youll gain a couple hundred in late SEPT,OCT nothing you can do but wait, raise it up untill speed drops then lower it back down until it gains top speed in 1/4 in increments

[RobFess]

get a vessel view and find out , its getting hot and humid youll gain a couple hundred in late SEPT,OCT nothing you can do but wait, raise it up until speed drops then lower it back down until it gains top speed in 1/4 in increments

I've picked it up until prop starts to slip and lose some speed and dropped it as you've said and see no change. When prop slips my rpm doesn't change either. I am talking with another person with this same boat and motor setup that is seeing the exact same issues after the powerhead having been rebuilt. I have found out that my motor (409hrs) was rebuilt approx. 38hrs ago and am wondering if something was done at that time by whoever rebuilt the powerhead. I cannot find a sticker on the rebuilt powerhead with the serial number to match the one on the tilt trim bracket so I am not even sure if it is a truly rebuilt head or if they slapped something else on it. I am trying to find out who did the work (was done in 2016 so wish me luck) and see if they'll give me any info.

[JOE54]

i have many references on this combo 72 is a fast one in cool weather empty /very light

[RobFess]

i have many references on this combo 72 is a fast one in cool weather empty /very light

I have a place to run below a dam. Air temp was 74. Water temp was 54 (dam tailwaters) the boat is totally empty less an ultrex, 3 group 27's and 1 group 31 battery, and me (190lb) and still only see 5500rpm and that 67mph and at 650ft elevation. This was the exact same numbers I saw all the way around when running it on Tablerock with 85 air temp, 80 water temp same load with an extra person (+200lb) and 915ft elevation. EDIT: This is also running with 10-15gal of fuel and 1-2gal of oil.

[JOE54]

digital engine temp please to verify thermostat operation would also suggest a verification of all other sensors and switches

[Bryanmc57]

i have many references on this combo 72 is a fast one in cool weather empty /very light

Isn't there a guy that lives real close to your shop that has one?

[JOE54]

6 different 206 champions very close one family has 2 i have a 210 here now with 3.2 300 stroker on it

[RobFess]

digital engine temp please to verify thermostat operation would also suggest a verification of all other sensors and switches

How would I go about getting digital engine temp?

[EuropeanAM]

Smartcraft Instrument, Display, or VesselView (several options).