2001 RX DI Runs, But Low Power

[RideRed0331]

I just bought a beautiful 2001 Sea-Doo RX DI with 200 hours on it. It was absolutely babied, and I purchased it from the original owner who reports to have never had an issue with it, and it has never been rebuilt. He described the issue as "having very little thrust". I have not water tested the ski personally. The ski starts and will idle on the trailer, and will rev (I have only blipped the throttle to see if RPM's come up, which they do) but it does seem sluggish to me. If I can figure out how to post a video of it running I will, I have a 10-second clip of it.

I compression tested the ski and am showing 110psi on the (front) mag cylinder and 120psi on the (rear) PTO cylinder. Full battery, wide open throttle when cranking.

I am very well versed in the Kawasaki 650 and 750 SX 2-strokes, but the Sea-Doo is new to me. Are these numbers low, and would this explain the low power issue?

 

[RideRed0331]

 

[KyleW2]

I want to say that ski should be around 135 psi in both cylinders, plus should have less than 5% difference in readings between cylinders. Yours is greater than a 5% difference and the mag cylinder is low. Was this tested with a known good gauge (not a harbor freight gauge)?

Yes low compression can explain the low power issue

 

[jhjesse]

Compression seems a little low. Also 200hrs is a getting up there for these engines.
In a perfect world 140psi is premium. I would be concerned with the psi difference between cylinders. Maybe try another gauge.

If you can, let us know how the water test goes.

 

[RideRed0331]

Gauge accuracy is unknown, but it certainly is not of Snap-On quality. I would estimate its reading low, if anything. I also researched a lot more on the fuel system issues known to plague these skis, and ordered a replacement in-line fuel filter and new direct-replacement fuel pump from Quantum just to rule those out. I have a feeling my issue is fuel related simply based on similar posts with similar problems. If I can get the ski out on the water for a few times this season (it will likely be used for three weekends total over the summer) and rebuild the engine during the off season, that's ideal!!

 

[jimmyluke]

Unfortunately you’ve done what a lot of us have done that have di skis and that is purchased a new aftermarket fuel pump most likely the one you ordered is a model HFP342di. Based on many experiences on this forum and a personal experience of mine an overwhelming majority of these fuel pumps don’t work from the get-go or last only a few hours until it loses fuel pressure. It would be a very good idea to be able to check your fuel pressure which should be 27 psi plus or - 2psi when installing the lanyard and 107 psi plus or -2 when cranking the engine or running. You hook up the fuel pressure gauge in line with the fuel pressure hose that has the in-line fuel filter in it coming from the fuel pump. Some have had good luck cleaning their fuel pump by removing the fuel pump assembly from the fuel tank then removing the fuel pump from the fuel pump module ( search on the forum here there are several articles on it) then let the fuel pump “self clean“ by letting it run for about an hour in A mixture of equal parts of gas and toluene which you can get at your local hardware store. Basically what I’m trying to say is you want to stick with your OEM pump. They have a proven track record of being better than aftermarket. And while you are at it and have your fuel pump assembly out change the two internal filters and of course change your external in-line filter.

 

[RideRed0331]

Thank you, I appreciate the response very much! Is there a how-to or YouTube video by chance for the fuel pressure test? I can probably rent a fuel pressure test kit from a local shop, which would be awesome to get a baseline before I really do anything to the ski in terms of a repair.

From what I'm imagining based on your directions I can probably just disconnect the fitting after the in-line fuel filter and put the gauge in-series with that line? Then install the lanyard, and then start the ski to check my numbers?

 

[RideRed0331]

This is the kit I ordered:

 

[WaarrEagle]

I just bought this pressure gauge set off Amazon for $35 to do some fuel pressure troubleshooting on my DI this weekend: https://www.amazon.com/gp/product/B00VV29NHM/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

It was recommended by another member on here.

 

[KyleW2]

Before going any farther I would go to Autozone and rent a compression gauge and see if you get better numbers. Just my opinion. I would hate to see you throw money at parts if the compression is causing the issue. Might as well check it while you are waiting for parts to come in anyway

 

[mikidymac]

As said above th aftermarket pumps suck.
No reason to replace yours until you get readings to confirm it is bad.

 

[RideRed0331]

So I did rent a fuel pressure test kit, and I was able to get it to work with some auto fuel line and zip ties. I had to eliminate the in-line filter during the test because of a limited number of connections adapters in the kit, but these were the numbers I ended up with. Unfortunately the gauge only went to 100psi, though.

Lanyard installed, engine not running:


Engine Running:

 

[jhjesse]

Umm...Have you water tested yet? If so, does the engine rev up and go nowhere or does the engine not rev up?
Also, have you compression tested the cylinders yet?
From the look of the pics you have good fuel pressure.