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tbullard

03 Wakesetter WOT RPM issue

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tbullard

Have been searching this forum for months finding tons of great info but just can't seem to figure out this issue so decided to join and ask directly.

I have an 03 Wakesetter VLX with the monsoon 335 engine. Boat runs great but tops out at 32mph and 3500rpms if I didn't know it was supposed to run faster and 5000rpms I wouldn't even know there was an issue other than it seems low on power once weighted for surfing. I have found that if I rev the boat out of gear that I can easily reach 5000rpm but not under load. I have run several tanks of fuel thru the boat this season so I don't believe it would be old gas.

I have seen similar issues posted here with several different fixes but nothing seems to make a difference for me. I figured it was either a fuel or ignition problem so I have replaced parts on both systems.

For the Fuel system new filter and cleaned screen on fuel pump, sent injectors to https://fuelinjectorconnection.com/ and ended up needing new injectors, replaced the Fuel pressure regulator while it was easy to get to. After this I am getting a steady 40psi fuel pressure throughout the throttle range and the boat does have a better take off from idle to full throttle with no hesitation but still tops out at 3500rpm.

For the ignition system I replaced Cap/rotor, Coil, wires, and plugs. The boat does seem to crank faster now but again tops out at 3500rpm.

I am at loss and not sure what else parts to throw at it. Only other parts that I have seem mentioned that could possibly give issues is the ICM or the TPS. Seems that if it was a temp sensor issue that would limit to 3000rpm and I am above that. Just don't seem to be getting any clues since it runs fine other than the RPM's are low.

Any ideas?

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formulaben

What prop are you running?

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csleaver

The prop used can greatly affect the wide open throttle rpms.  The ACME 537 13.5x16 is a pretty common prop for that boat, but may not work well at high altitude or with heavy loads.

I would recommend a compression check on the motor, and change the spark plugs while you are at it.  Also, make sure your tachometer is not giving you a false reading.  Any decent digital timing light should allow you to check the rpms.

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tbullard

I knew I should have added the prop info. Not sure of the exact number but it is the stock prop and I am at 330 feet so I don't believe that should be the issue.

I did figure out today how to read the fault codes using an led

I was seeing

14 Coolant Sensor Voltage High (cold)

21 Throttle Position Sensor Voltage High

34 Manifold Absolute Pressure Sensor Low

42 Electronic Spark Timing Grounded Circuit

I have changed the Coolant sensor so that may be an old code. Looks like the TPS code may be related to the TPS voltage not matching engine RPM which would be correct since it is asking for WOT but only seeing 3500 rpms. Haven't changed the MAP sensor would that code indicate it was bad or something similar to the TPS? Not a clue what the Electronic Spark Timing Grounded Circuit code is but I have changed everything on ignition end so maybe it is an old code also.

I cleared the codes and plan to run the boat tomorrow so I will check again then and see which codes come back.

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formulaben

The TPS and MAP sensors are relatively inexpensive and stupid easy to swap out.  Just bring in the old ones to a local auto parts store and search under 1999 Chevy Suburban 350 and confirm a match.  If you go to a marine store and get Indmar parts they will be over $300 for both of them, but these 2 should be around $50...so if it was me, I'd just get new parts to eliminate them as possible culprits.

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tbullard

Good call just ordered them from Amazon.

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tbullard

The ICM was the only ignition component that I didn't replace and I did that today. Took it out this afternoon and its like new boat!!! 4800rpms and 43mph  greatly improved performance throughout the throttle range where it would normally start to bog when making a turn at 20mph it now powers thru and never losses speed.

I feel like everything I changed was needed and appeared to mostly be original to the boat so I don't mind that I was throwing parts at the problem but for anyone reading this thread in the future the first thing you need to do is check the codes as mentioned in the 4th post as in my case code 42 would have told me to change the ICM from the beginning.

So happy to have this resolved but since I got a good deal on the boat due to the issue also glad it existed :)

 

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