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Not reaching rpm /not planing

R

Robotdr

New member
i have a 2767 Carver with twin 4.3L Mercs. - Alpaha One outdrive.

Last year Starboard Engine would not hit rpm range - 4400-4800 - (i never push more than 4200 but maxed at 2500 Rs), cleaned carb (4B QuadraJet), achieved RPMs, got on plane, all good for season.
This year same thing happened to Port side engine (maxes 26-2800 Rs and no planing), easy to assume it was the same problem, cleaned carb,
problem still exist. 2800 Rs, no planing.
not overloading boat; dump all water, less than 1/2 tank of gas, just me testing rig, calm water...still nothing.
stock props, stock upper gears, worked fine last season.
The only thing i can think of is spun hub, but not convinced of spun hub cuz had this problem since i put in the water this season, it never reached
rpm ranges this year. boat was stored indoors in heated facility

WTF????????????????


Robotdoc
 
Last edited:
A spun hub will send the rpm to the moon!

I suggest adding a temporary fuel pressure gage after the fuel pump to see what's happening. If the problem is fuel related, you'll know immediately.

Jeff
 
i wasnt convinced it was the hub because when i measured the carb float it read 14/32", spec calls for 9/32".
it was getting late and did not want to take it apart again.
since i suspected fuel issues (which is why i rebuilt carb) i was thinking 5/32" may not a be an issue. i understand
the pin would shut supply sooner, but since i dont have dieseling or flooding problems, i wasnt concerned. The bowl
would be close to empty at high rpms.

the engines overheated at one point in spring...i did alot of repairs to both engines and have not been able to plane since, however,
with this said, i cant figure how overheating eng. would cause this issue. all pistons show average of 125-130 psi. pretty consistent.
no water in oil system so head gaskets are ok...theoretically.

i can check filter and pressure, after that, not sure what to think without taking tank apart and checking lines, etc.
 
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