09-07-2007, 05:01 PM #1
Trouble Shooting Speed, Leaks, Overheat, etc
Some things/tips I have learned/recorded that hopefully will help others. Feel free to add more.
Trouble Shooting Speed, Leaks, etc.
Low rpm and low speed
Boost leak – check IC hose clamps, spray soapy water & test ride look for bubbles.
SC slipping – slip should be 8 – 12 ft lbs, or 96 – 145 in lbs, more for higher boost chargers. Add new washers, McMaster washers, or shims.
Steep prop/bad prop – follow recommendations for skis like yours on the forum for exact prop and pitch.
Bearing in pump bad – can usually hear the bearing start to howl.
Too tight nozzle ring – try larger ring.
Heat – hot weather can steal 200 rpms. Upgrade thermostat to help.
Not enough intake air – go 4 inch intake, front or rear.
Bad wear ring – replace or go SS.
Bad spark plugs – rare, but happens, replace.
Dirty injectors – rare, but try some cleaner.
Bad gas – usually runs rough too.
Low fuel pressure – rare, but can happen if there is a crack in the fuel system.
Oil level too high – dealers do this often, suck some out. Should be between the two marks hot, idle 30 seconds, shut off, wait 30 seconds and check, must be level.
Exhaust leak – take seat off and run to verify (should run noticeably faster without seat). Check J pipe clamp and fit to manifold. Look for carbon on and around the J pipe. Take it off and leak test.
Nose cone loose (cavitates) - check underneath, re-attach or just eliminate nose cone altogether.
Leaking intercooler – runs crappy at higher rpms. Pull IC to TB hose, run, check for water in IC.
Low speed, good rpms
On rev limiter? If you are hitting 8150 rpms (stock ECU) or higher, you are likely ON THE LIMITER and you need a bigger prop or tighter nozzle ring.
Too small prop – Stick with 14/19 with stage 1, 15/20 with stage 2 and beyond, bend trailing edge 1mm at a time to adjust rpms.
Too big nozzle – try smaller nozzle ring (if you have adjustable nozzle installed).
Pump shoe not flush – happens on some slow boats, not installed right, hangs too low. Fix.
Ride plate hanging down – intake grate, pump shoe, ride plate should all be flush.
Bad wear ring – common, replace.
Impeller not 'true' – fix it, have a pro fix it, or try another buddies known good impeller.
Poor motor alignment – often go thru carbon rings quicker this way too.
Check carbon ring and accordion boot, replace if needed.
Check wear ring.
Check condition of impeller.
Check impeller nose cone, make sure its still on tight.
Overheat (exhaust overheat, not motor)
Intercooler plugged? Flush intercooler, or replace it if the water passages are blocked. Pull the IC, blow it out, and try to breathe thru the water passages; toss it if you can't easily inhale a full breath thru it.
Modded waterbox? Try stock waterbox if still available.
J pipe water exit holes (3 pinholes) might be plugged, or clamped wrong, closing off the holes (watch where your upper clamp goes). Can also drill out J pipe pisser holes one size larger.
Add a garden hose blockoff to your flush adapter (to the upper right of the jet pump), screws right in, and can close it to force more water into your system. Altho this is usually a band-aid for the real problem, it often eliminates the overheat.
Water in hull
Cavitating too? Likely need new carbon ring and/or accordion boot.
Motor mount might be broke – allows even a ‘good’ carbon ring to leak under acceleration.
Stock bilge system not working correctly, putting water INTO the hull.
Crack or leak in exhaust system/waterbox, leaking water into hull.
OPAS or OPAS blockoffs leaking.
Bad rubber seal under front bucket, leaking when hitting big waves in no wake zone, etc.
Split or leaking IC/exhaust cooling hose (3/4 inch hose off the pump housing bleed).
Boost good, rpms good, speed low
Try different impellers, borrow a good one, double check / tweak yours, do whatever it takes.
CLEAN UP YOUR BOTTOM – everything should be smooth and flush. Pump shoe to hull, intake grate to pump shoe, ride plate to pump shoe. Mismatches DEFINITELY will slow you down!
Try different (tighter) nozzle.
Make sure your pump components fit together right and are installed right. A gap between the pump and thrust nozzle will bleed off thrust and speed.
MAKE SURE you are not sitting on the rev limiter without realizing it. Try to keep rpms at 8100 range (if stock ECU) to ensure you are not limiting yourself.
All the above apply if you have not pulled the motor, or the head, or swapped cams, etc. IF you have pulled the head, there are other possible issues, listed below.
If you have messed with cam timing at all, it is easy to get it wrong. Make sure to check compression before dumping it in the water. Compression should be 130 - 150 psi cold, plugs in. Cam timing can be adjusted with the bolts in the slots to affect timing, compression, and performance a bit.
If it idles rough, and runs rough in lower rpms, cam timing is likely off.
If compression is lower than 130 lbs with cam bolts in different positions, cam timing is likely off.
If OIL pops on the display as you initially accelerate past 5000 rpms, your oil pressure sensor is likely bad (especially common on 2004 - 2005 skis). Replace it with a brand new sensor and try again.
If a new sensor did not correct it, you may have a stuck/scored/crushed oil pressure regulator. This is located in the bottom of the PTO; motor must be lifted to get at it. If you have had a ceramic failure or something has fallen in the motor, the oil screens might be plugged too, take a look.
Last edited by Vern; 06-18-2010 at 03:55 PM. Reason: Updated again
09-07-2007, 05:54 PM #2
- Join Date
- Jul 2005
- euxton nr chorley lancashire, england
good write up vern,
09-07-2007, 06:37 PM #3
09-07-2007, 06:42 PM #4
Vern but what if my WHATCHCALLIT ends up getting next to my THINGYMAJIG and gets EVERYTHING CATTYWOMPUSS!!!!!! i DIDNT see the answer for that! just teasin Vern! NICE POST BRO!
09-07-2007, 10:13 PM #5
- Join Date
- Oct 2005
Great post Vern. This is exactly what I had in mind a while back. Maybe you saw? I didn't have time to sit down and think of everything out because of moving back to school and such.
I seriously think this should be made a sticky. The more things that are added to Vern's list the better. I think this will save us the grief of having mutiple low RPM threads everyday. This should really help out the newbies, and even those of us who are having trouble narrowing down a problem on our own.
Thank you Vern.
09-07-2007, 10:15 PM #6
This might be a great candidate for the FAQ section instead.
09-07-2007, 10:38 PM #7
09-08-2007, 02:07 PM #8
i had a weird overheat issue recently.
i found that the j-pipe to waterbox coupler had slightly melted causing an overheat issue.
When the coupler melted it formed a perfect circle that blocked off the pisser holes on the J pipe.
so if you have an overheat and find what you think is the solution to it, but still have heat issues check your coupler to see if it is restricting your pisser holes.
09-08-2007, 10:19 PM #9
Would'nt a smaller ring take away more rpm's ?
09-09-2007, 12:39 AM #10
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