over rev on a 5.0 merc.

My friend ownes a Regal 2000 2004 with a 5.0 mercruser and propelled
by a 14.25 x 21 wich had been reweld last winter because of an earlier
smash ... he put his boat in the water today and his engine was running idle
at 1000rpm and at 6000rpm at full . something is wrong for sure and we tried it at 3500rpm and he was running 20 mph . do you guys think its the rebuilt prop or it could be something else ??

thanks for your input.

Re: over rev on a 5.0 merc.

he needs to check out his tach.

Re: over rev on a 5.0 merc.

The tack/RPM gauge sounds like it is out of aujustment or it is a bad gauge. Take a flash light if needed and look at the back side of the gauge in any way you can and reset the little knob, You normaly will need a small flat screwdriver to turn the dial. Some times you just need turn it a little and then just center the arrow to the number making sure the knob pops out a little, For a V8 the number normaly should be set to [#3] But to be 100% there should be a sticker some place on the gauge some place that tells you what number to set it at. Also try taping on the gauge to see if it changes any while running the engine out. That engine should idle at 640rpms and max out around 4850 to 5000 rpm range. Good luck I hope this helps you out.

Re: over rev on a 5.0 merc.

Thanks for your help .... we will try to adjust it next week-end ....
if other people have other idea that may hapenned let me know.