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2005 kawasaki STX-15F will not go above 5200 RPM

6K views 6 replies 5 participants last post by  duckawi 
#1 · (Edited by Moderator)
Hello: got myself in a little trouble with this ski, I bought with the problems thinking I could fix it but it was not what I thought it was. Problem: ski will run on all 4 as long as it does not go above 5200 RPM, the thing that have been done has been new fuel pump, filter, and fuel lines, no help, new coils no help, I have metered all the inputs to ECM and they appear to be normal. Oil is good, new oil and filter. According to old owner he install a new wiring harness, but I think it was used but was done, old owner told me this just came on no warning, one day working fine next wouldn't go above 5200 RPM, any help would be great. Thanks
 
#2 ·
This could be a tough one for me personally. Have you verified the oil level at operating temp (after about 5 min of easy riding) ? Open the air box and look for oil. I believe there is a sealed tube that comes off the air box also. Check and make sure it is empty.
 
#3 ·
Does it go past 5200 rpm and then just runs on three cylinders or won't go over 5200 rpm at all ? Have you tried a tune ? The only things that can stop a motor from reving is Air/Fuel/Electrics, is the ribbon in the air intake half blocked with carbon or rubbish ?
What does the compression test say for each cylinder, have you checked spark plugs to see if they stay clean or are they dirty after running are three dirty and one clean or three clean and one dirty ?

Are the fuel injectors all working. Is it the same cylinder that doesn't run or do all 4 cylinders start to break down ? If one or two fuel injectors are not working at higher revs that could cause the problem as well.
When you get to 5200 does it just die or still rev faster but like it has no power, is your accelerator working correctly ? My Ski has a wireless accelerator, have you checked you are getting full movements ?
Personally I would spend the $300 on a service and ask the experts that work on them every day :) it will save you a lot of time and money long term as you could just keep spending more money on the wrong things.
My thought is either ribbon is chocked or Fuel injector/s.
Good luck and I hope you get it working :)
 
#4 ·
thanks for getting back to me, I have tried all the suggestions you talk about with exception of injectors. I just took it out to the lake this afternoon and tried it again with new plugs, ecm, air intake off, coils (both), and did a little more troubleshooting. I found that when it was real cold just started it up it right up to 7800 RPM (on rev limiter) and everything looked good. I shut it down and replaced air cleaner, and started it up, now it up to 5200 missing just like before, took air filter off again and same problem, now it seems it was jut cold and after it heated up back to same problem. Next I started removing plug wires and giving it throttle, 4,3,2 were the same as before but number one it just went up to around 4800 and acted like it was on the rev limiter, not a big miss like before, replace plug with back to 5200 and missing real bad. I dont know how to test the injectors can any one help with that. Thanks. P.S. Sorry it took so long to get back but was sick and surgery.
 
#5 ·
Well that is pretty clear then that something is heating up and causing a problem, now you just need to find out what part is getting too hot, maybe a faulty heat sensor telling the computer system that the engine is getting to hot and so lowers the revs, or something similar to that.
My Ski when it had a broken hose clamp ran too hot and so wouldn't rev, I don't know what revs it would go to as I just virtually idled back to shore.
It should show a light on the dash though if the engine is getting hot ?
Maybe call a Mechanic and ask if he has come across that problem and he may tell you to check a certain part ? They can be helpful at times ?

Good luck :)
 
#7 · (Edited)
Check compression, especially cylinder 1. Water intrusion from the top is common cause, spark plug seat corrosion. Happen to my 15f. Previous owner over tighten spark plug to compensate; you know the kawi story, spark plug broke off during removal. The corrosion is visible when the washer is removed. Solution, remove broken spark plug. Drill out with time-sert tool with counter sink. The insert will have a shoulder to fill in counter sink creating a new seat. Tool is not cheap, dealer's price for complete job varies $930 to 1500. They remove the heads to avoid any further damage.
Amazon.com: TIME-SERT M10x1.0 Extended Spark Plug Repair kit P/n 4010EXT-133: Automotive
 
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