i have a 07 40hp 4stroke EFI and can not get max rpms or top speed.I have gone through the whole fuel system ,from inside the tank all the way through the injectors, and every thing checks out fine.I changed the spark plugs also and still no luck.The motor starts,idles,and runs fine just cant get over 4200 rpms or 10 mph. Any advice would be greatly appreciated thank you.

May have too large of pitch prop for the boat it's on.

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Sorry I forgot to mention I was running 5600rpms at 23mph until my fuel line from the tank to the motor got plugged with the liner from inside the hose thanks to ethanol gas.

Ok, I recommend checking compression, just to be certain. However if you have not had the computer diagnosed try that, sometimes computers will go into a guardian mode which has to be removed by a dealer with the computer.

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Sorry it took so long for a reply but thank you very much i will schedule to bring it in for the dealer to check it and will post an update when i get it done