2005 sea doo islandia Rev limit

[JohnnyG22]

Hello everyone, long time follower first time posting.
So I bought a 2005 Islandia with a rebuilt 240 Mercury. Did most the work my self following lots of advice from your post especially Doc Honda. This weekend I replaced the wear ring with SS and hi skew Impeller from Ex weld in Canada. Boat planes a whole lot better and tops of at 33 MPH but the RPM only hits 4,900. I know this boat should do at least 5650 RPM. It did that even before I replaced Ring and Impeller, thought it might help but it didn't. There then that everything runs super Smooth. Don't know where to start looking. Spark Plugs? Rev limiter? Temp Sensor? Please Help. Thank you everyone

 

[ripcuda]

I too am dealing with an engine that can't rev to max.

Sounds like your engine starts and idles fine.

Pull the spark plugs and inspect them. If one or more doesn't look like the others, that's a clue.

With spark plugs out, use a compression tester to get compression readings on each cylinder. Being a rebuild engine, should have good compression #s like 135+ psi.

Does you boat have the Throttle Guardian in it? (mine does not) If so, you might want to test it without the TG hooked up to ensure it is not messing with revs.

Are you getting proper 35psi fuel pressure at idle and at speed? (test via schrader valve on VST)

Cheers!

 

[JohnnyG22]

Thank you for the quick response (ripcuda). 1St thing i checked was the Throttle Guardian and no already removed.
engine have about 50 hrs maybe since rebuild. Boat is 2005 was originally a 250 optimax but now is a 2000 with the 240. Pretty much same engine. Spark Plugs is my next move. and then Fuel Pressure. Boat starts, runs and planes amazing. I just can't help but think i can get more out of it if i can hit those last 750 plus RPM's especially Top speed.

 

[Tim75]

I too am dealing with an engine that can't rev to max.

Sounds like your engine starts and idles fine.

Pull the spark plugs and inspect them. If one or more doesn't look like the others, that's a clue.

With spark plugs out, use a compression tester to get compression readings on each cylinder. Being a rebuild engine, should have good compression #s like 135+ psi.

Does you boat have the Throttle Guardian in it? (mine does not) If so, you might want to test it without the TG hooked up to ensure it is not messing with revs.

Are you getting proper 35psi fuel pressure at idle and at speed? (test via schrader valve on VST)

Cheers!

When you do the compression test, all plugs out, full throttle WOT. Not in the water.

 

[JohnnyG22]

Got ya, don't mess those days. Old gear head here, rebuilt and trouble shooted so may cars and trucks in my day, but this boat/marine thing is a whole deferent beast. LOL But i'm learning all over again. Thank full for my auto back ground. it does help a lot in understanding.

 

[Tim75]

Got ya, don't mess those days. Old gear head here, rebuilt and trouble shooted so may cars and trucks in my day, but this boat/marine thing is a whole deferent beast. LOL But i'm learning all over again. Thank full for my auto back ground. it does help a lot in understanding.

The 250 Optimax and 240 EFI are not really the same engine. Aside from displacement, the air compressor, the higher fuel pressure, the larger physical size and weight, auto-type alternator; not really the same. Are you the person that did the swap? What difficulties did you encounter?

 

[JohnnyG22]

No, a Shop had the rebuilt engine already and said it would be a easy swap.

 

[JohnnyG22]

Do you think the Temp Sensor would affect RPM if out of range?

 

[Shortrun]

Just a wild guess.
Unlike cars, 2 stroke engine really care about the exhaust system.
Possible this Merc engine has all the important parts built into the engine, i dont know.

Is it possible the 2005 Islandia mufflers are different from what your engine needs?

 

[JohnnyG22]

Well looking at both from outside i would say no. they look the same. Mercury Dealer did the work. They had a 250 i was checking out but hard to tell deference when engine cover is removed. Its Gen 2 cause it doesn't have the round cover.

 

[ripcuda]

Air Temp sensor or Head Temp sensor (port-side)?
[240efi gen1] The Head Temp sensor is directly wired to the TPS to vary the reading the ECU sees from TPS based on how hot the engine is. If this sensor fails... the ECU will see erratic values (like also if TPS fails) and will richen the mixture by 40%. This would make it run rough and smoke. But at WOT, the ECU ignores the TPS... thus why when folks have a bad TPS... they can still go WOT and have it seem normal. So I don't think those sensors would be affecting your limited max rpm.

Cheers!

 

[JohnnyG22]

also any idea on the S/N there doesn't seem to be one on this engine. looked close every where that it should be. Do you think Mercury would be able to pull from Computer? Thanks
Driving me nuts now for 2 weeks. I don't know if it was removed or lost during rebuild.

 

[Tim75]

also any idea on the S/N there doesn't seem to be one on this engine. looked close every where that it should be. Do you think Mercury would be able to pull from Computer? Thanks
Driving me nuts now for 2 weeks. I don't know if it was removed or lost during rebuild.

S/N should be on a sticker on the plastic flywheel cover.
There should be a separate S/N for the pump stamped into a metal plug just below the shift cable outside the boat.

A good, customer-centered dealer should still be able to look up parts for you. Have some pics with you. Pack your patience and extra $. Some of the parts are stupid expensive.

 

[JohnnyG22]

Thanks Tim, you been a good help. Still no luck on S/N found Sticker on the fuel pump housing but not Motor. I Keep Looking.

 

[Tim75]

Thanks Tim, you been a good help. Still no luck on S/N found Sticker on the fuel pump housing but not Motor. I Keep Looking.

Not the fuel pump.
The jet pump. Under the boat. Just below the shift cable is a flat metal plug that should have the pump S/N on it.

 

[JohnnyG22]

ok, will look on Friday, raining pretty bad today. Thank you again. But also I checked the throttle body today to see if the butter fly was opening all the way and its not. There is a set screw and nut that hits about 90% and not letting throttle open wide 100% gonna try adjusting that Friday also and see it it will make a difference in the lost 900 RPM.

 

[Tim75]

ok, will look on Friday, raining pretty bad today. Thank you again. But also I checked the throttle body today to see if the butter fly was opening all the way and its not. There is a set screw and nut that hits about 90% and not letting throttle open wide 100% gonna try adjusting that Friday also and see it it will make a difference in the lost 900 RPM.

The throttle body is like and old 4 barrel carb. 2 primary throttle plates and 2 secondary plates. All 4 should be wide open at full throttle (helm). DO NOT attempt to remove the throttle plates.

 

[JohnnyG22]

Trust me i'm not. I just see there is a stop screw that is set so they don't open 100%. Gonna adjust a little to allow it to open completely