Mercury 200 efi running high rpms?

[fishsniffin]

MERCURY 200 EFI serial no: 0G406279. Up in Clear Lake, ca. The lake is in an algae bloom. My motor is not getting a proper water psi reading, and the rpm is going upwards of 6300k at only 45mph and I'm not pushing it anymore than that. I'm staying within 5500-5900k which is the norm for my motor...could the algae in the water cause a blockage somewhere? I've already hooked up the muffs and flushed it for 5 mins, still no change.

[micropeterous]

If you are talking about the thick gooey type algae bloom that Clearlake gets it could easily plug the intake holes in the gearcase. It could also make its way up to the water pressure line that runs from the engine to the gauge. The speed vs rpm issue sounds like a spun/slipping prop hub problem.

[fishsniffin]

Hmmmmm....I just had the hub replaced 2 months ago, I spun a hub then.....could it be slipping again?

[fishsniffin]

Weird thing is, my buddy's boat with a mercury 200efi is doing the same thing....wot at close to 7k when normal wot is 6800

[JOE54]

guess it could id check pump too,never seen algea like that though, bud better get those rpm down 68 still way too high

[rchavis]

I would also have your rpm gauge check to .....6800-7000 it want last long over 5800, with out the oiler off and motor mod .

[leonreno]

Wonder if all the algae in the water is putting a much heavier load on the prop and hub, thus causing the hub to spin?

[fishsniffin]

How would I check the hub...take it off?

[JOE54]

yes ,look at surface next to thrust washer for signs of slipping or melted rubber on inside or prop shop

[mdtritn21]

You can put a mark on the prop hub and on the nut hub washer and see if it moves when you run it.

[EuropeanAM]

Mercury - 2.0/ 2.4/ 2.5 Liter High Performance
For discussions related to 2.0/ 2.4/ 2.5L motors.