67 Mercury 95 horse tower of power serial # 2212337, sluggish and popping at wot

[opalized1]

motor has sat for 10 years im sure, I just got it, installed on my boat, changed lower unit lube, replaced impeller, then put it in the water and ran 10 gallons of gas through it with sea foam and proper mix 50/1, most of the running was at just above idle ran fine, trolling the lake for sharks. anytime I attempted to get full throttle out of it, the boat would only achieve maybe 10 to 15 mph, with a noise similar to detonation, or popping, a check of linkage its achieving full throttle at carbs, distributor is rotating, spark advance, everything was greased and movement checked, a secondary not, I have tons of water coming out of prop, and vents below water inlet, but none coming out at 2 top weap holes, a check of motor after running there is no heat in the area around sparks plugs or any of the 4 sides of the motor, 2 sides literally cold, and the exhaust and spark plug sides slightly warm, but you can hold your hand on them without getting burnt, after the first day, I brought it home pulled plugs checked compression, 90 lbs on all six cylinders, replaced plugs with new, and return to lake next morning with a second tank of fresh gas, pre mix 50/1 and more sea foam in gas, ran the same way all day, minute improvement at times could be heard in just of idle tone, but exactly the same at wot, seems to have great spark, I pulled a plug wire while running and got the shock of my life, the fuel tank was spotless when installed fuel filter shows no debre at all and carb fuel filter is spotless, any thoughts, I will be returning to lake this weekend to run some more gas through it, I had removed plugs after second day out, and soaked cylinders with sea foam, with motor up, the motor fires cold just fine, restarted once warm without even rotating a full turn, runs great off idle, just no top end

 

[racerone]

I would take the carburetors off for cleaning.------You can not risk running that motor with a plugged carburetor.-------No fuel means no oil to 2 cylinders.----Verified that the belt timing is correct ?----Fuel pump /s checked for leakage ?

 

[opalized1]

easy starting hot or cold, good idle and acceleration off idle wouldn't be a fair indicator timing was fine, once warm just touching the key and the motor is running, absolutely no rotations, no stumble when putting in gear, forward or reverse, fogging the motor through carburetors while running above idle, does not increase rpms at all, which would seem to indicate all 3 carbs are providing fuel at idle and just above, this includes fogging with wd-40, which in prior uses on other motors would increase the rpm being a flammable, but no increase on this motor??
no leakage seen anywhere inside motor cover with motor running or off, ran it for some time with cover off, watching listening as the throttle was cycled from idle to full throttle, to confirm linkage was working and carb linkage was functional, full throttle at controller is fuel throttle at linkage on all 3 carbs.

what about no water at 2 upper vent holes, occasionally alittle exhaust can be seen, but no water>?? when I pulled the old impeller off, the tube that comes out the top off the impeller housing connecting the tube going up the lower unit attachment point, the plastic tube was shoved all the way up that tube, disconnected from top of impeller housing

 

[merc850]

90 psi is not the best, compression-wise it should be closer to 140; the plastic tube is a guide for the water tube to pump assembly you put it on the pump then put the water tube into it as you re-install the LU.