Low RPM and low top speed RXT260

[surfingboyo]

I've been having issues with a low top speed (103km/hr) and low max revs (7200rpm). Accelerates very slowly in normal mode. Normal key fitted. Ski is a 2014 RXT260X.

Here is a list of replacement parts and testing I have done on it so far:

-new throttle body (TPS reset)
-new intercooler -replaced map and mat sensor
-new spark plug and oil filter
-supercharger just rebuilt
-rebuilt jet pump and pump seal
-solas 15/21 in new condition with no nicks
-new wear ring
-cleaned and tested injectors
-coolant leak test (no leak)
-compression test (strong compression)
-boost leak test (no leak)
-intercooler leak test (no leak)
-no cracks in intake manifold

Anyone with some thoughts on where to go from here?

The video below is not mine, but exact same symptoms as mine.

[Green Hulk]

-compression test (strong compression)

What are the exact compression numbers on all 3 cylinders?
Why the 15/21 impeller...... What mods are on the ski?
Regardless of the supercharger just being rebuilt, what is the slip moment of the supercharger clutch? You'd be surprised at how many people I see screw up a supercharger rebuild and it has very low slip.

[Myself]

Also does the inside have a gas fume smell after a ride? Seems like the top of the fuel pump module likes to crack on those. it starts out just like that, then gets worse to the point it will throw a code and go into limp mode. The crack is pretty hard to see and at first won't leak until maybe 1/2 or more throttle. After a full throttle run pull out the storage bin and take a sniff or look for raw fuel on top of the module and tank.

[surfingboyo]

What are the exact compression numbers on all 3 cylinders?
Why the 15/21 impeller...... What mods are on the ski?
Regardless of the supercharger just being rebuilt, what is the slip moment of the supercharger clutch? You'd be surprised at how many people I see screw up a supercharger rebuild and it has very low slip.

Compression numbers:
1 145
2 155
3 165

With a bottle on the coolant overflow, it does collect a bit of coolant. I bought the ski with a blown head gasket 12 months ago. I replaced the gasket when I bought it, had the valves cut in, skimmed head, pressure tested the head, but I think even since then it has pushed coolant. I don't think it has even revved out properly since owning it.

I have always been suspect on the head gasket, but everyone I speak to says it would usually still hit full rpm and speed. Replacing head gasket and checking it's true was going to be what I did next.

I did note some oil on the plugs last time I pulled them. Oil level definitely at the lower bend. Figured it was probably those seals.
seals.

The ski is stock. I'm guessing the previous owner replaced the impeller due to damage. The 15/21 seems to be the stock replacement on the Solas chart.

The ski had the exact same problem before the supercharger rebuild. Slipping moment was in the band, think it was 10 or 11 Nm.

[surfingboyo]

Also does the inside have a gas fume smell after a ride? Seems like the top of the fuel pump module likes to crack on those. it starts out just like that, then gets worse to the point it will throw a code and go into limp mode. The crack is pretty hard to see and at first won't leak until maybe 1/2 or more throttle. After a full throttle run pull out the storage bin and take a sniff or look for raw fuel on top of the module and tank.

No fuel smell or fuel showing in bilge water. The fuel pump has been replaced and I was having the issue both before and after. Cheers.

[Myself]

Have you gone over the exhaust thoroughly? Maybe there's a small leak somewhere and the engine is ever so slightly choking on fumes?

[surfingboyo]

Have you gone over the exhaust thoroughly? Maybe there's a small leak somewhere and the engine is ever so slightly choking on fumes?

I have had the exhaust off a few times. Also runs the same with the seat off on the water.

[1tommygunner1927]

I've been having issues with a low top speed (103km/hr) and low max revs (7200rpm). Accelerates very slowly in normal mode. Normal key fitted. Ski is a 2014 RXT260X.

Here is a list of replacement parts and testing I have done on it so far:

-new throttle body (TPS reset)
-new intercooler -replaced map and mat sensor
-new spark plug and oil filter
-supercharger just rebuilt
-rebuilt jet pump and pump seal
-solas 15/21 in new condition with no nicks
-new wear ring
-cleaned and tested injectors
-coolant leak test (no leak)
-compression test (strong compression)
-boost leak test (no leak)
-intercooler leak test (no leak)
-no cracks in intake manifold

Anyone with some thoughts on where to go from here?

The video below is not mine, but exact same symptoms as mine.

It could be a lack of fuel; dirty/clogged fuel strainer and/or fuel filter, or dirty injectors, or the wrong injectors. They should be 48's. How do the the spark plugs look?

[surfingboyo]

It could be a lack of fuel; dirty/clogged fuel strainer and/or fuel filter, or dirty injectors, or the wrong injectors. They should be 48's. How do the the spark plugs look?

I have replaced the fuel pump, associated filters and had the injectors cleaned and flow tested. How do you know if they are 48's? Spark plugs look oily.

[Green Hulk]

Have you tried running with the seat off to see if the RPM's come up? If they come up then you have an exhaust leak inside the hull.

[1tommygunner1927]

I have replaced the fuel pump, associated filters and had the injectors cleaned and flow tested. How do you know if they are 48's? Spark plugs look oily.

The stock fuel injectors are 48's. While 42s can plug into the fuel rail and intake manifold, the electrical connectors are different. Post a photo of the 3 spark plugs.
There shouldn't be oil anywhere on the spark plugs.

Inspect the spark plug tubes & seals, replace if needed. Before installing the coils, coat them with dialectic grease top to bottom, including rubber donut.
The hinged seat is not easily removed, but the storage bucket can be removed.

[surfingboyo]

Have you tried running with the seat off to see if the RPM's come up? If they come up then you have an exhaust leak inside the hull.

Yep, last ride I held it open and rode full throttle. No improvement.

Do you think a blown head gasket would give the same symptoms? And would it usually indicate a leak when you connect a pump to the coolant reservoir and pressure the cooling system?

Or could it be ECU tune related?

[surfingboyo]

The stock fuel injectors are 48's. While 42s can plug into the fuel rail and intake manifold, the electrical connectors are different. Post a photo of the 3 spark plugs.
There shouldn't be oil anywhere on the spark plugs.

Inspect the spark plug tubes & seals, replace if needed. Before installing the coils, coat them with dialectic grease top to bottom, including rubber donut.
The hinged seat is not easily removed, but the storage bucket can be removed.

I'll take a picture of them later today. Is it worth borrowing some coils off a buddy to try swap in? Would they give me similar symptoms?

[Myself]

Do you think a blown head gasket would give the same symptoms? And would it usually indicate a leak when you connect a pump to the coolant reservoir and pressure the cooling system?

Not full of coolant unless it's real bad. Drain all the coolant, THEN put 20psi into the coolant side and use a mechanics stethoscope to listen in each plug hole. I've replaced several head gaskets on 'Doos.

[1tommygunner1927]

I'll take a picture of them later today. Is it worth borrowing some coils off a buddy to try swap in? Would they give me similar symptoms?

If it were my ski, I'd clean the coils with WD-40, then coat them with dialectic grease, reinstall. I'd also address the ignition coil tubes if oil is coating the spark plugs. If the oil is one the sparking end of the plug, perform a leakdown test. If you did not use "flood mode" for the compression (throttle wide open) test, redo that first. Oil on a spark plug could be bad valve seals, bad valve guides, or both, or worn piston rings, or bad head gasket.