2000 30 hp johnson "sluggish"

[ray 14]

I recently purchased a 14'5 crestliner SC with a 30 hp johnson 2stroke, year2000. The motor starts great, idles fine, however, with two of us in the boat at full trottle the boat seems sluggish. The rpm's will not go above 4000. The operating spec's says 4500-5100. It takes a while to plane the boat and get to 5-8 mph. It also seems to burn through a 6 1/2 gallon tank in a short time.

I changed the plugs this spring (champion).

I will bring it to a marina this fall, but I was wondering what to ask or tell?

Thank you for the input

 

[steelespike]

Re: 2000 30 hp johnson "sluggish"

really need rpm and speed to get an idea where you are at.If your only reaching 5to 8mph something is screwy.Bad speedo,bad Tach motor trouble possibly running on one cylinder.How does it do with one aboard.What hole is it trimmed to?Is the antivent plate(just above the prop)even with the bottom of the boat?Considered a starting point.
A 30 will burn about 3 gallons per hour(gph) at wide open throttle(wot)