I have a pair of 525 efi's one will only turn up 4500 with new plugs and and all new filters any help.

fuel pump??? I think there is an electric and a mechanical. Someone wiser will opine.

there is low feed and high psi for the injection it just runs fine the rest of the time it just wont turn up.

what are these engines suppose to turn at max rpm??

5450

4800-5200 is merc spec's.try 2" smaller props.you gain/loose 150rpm per inch of pitch

I am experienceing same issue on my formula 400 with twin 525's - 1 of my engines will only throttle up to 4000rpm. i was thinking fuel filter as the other engine runs fine. How did your sutuation resolve itself?

Any feedback would be great!