dont trust the mech.

[hvachillbilly]

i own a pontoon with a 60 hp big foot efi (2003) just had the lower unit replaced and the power head removed to replace the steering arm on engine got the boat back with a 14 x 10 prop took out for a test drive i was running 5800 rpms at wot with no increase in speed from 5500 to 5800 so i ran at 5500 for 5 to 8 minutes and the alarm goes off took back to shop they changed the prop to an 11 pitch now wot is at 5200 is there a problem with my tach? how do i test? is there something else making the over rev alarm go off not sure what tells the computer the rpms of engine any help is appreciated

 

[199675hpforce]

Re: dont trust the mech.

Mine didnt something similar, have a look at the tach on back side. Play around with the adjustments, sometimes thats need to get working again. Different pole settings are a mistery to me but maybe someone can help you out. Turn em

 

[hvachillbilly]

Re: dont trust the mech.

thanks do you know if there is a way to get true rpms off the motor

 

[Jeff_G]

Re: dont trust the mech.

There is no over rev alarm. If it is a solid tone you are overheating.

 

[hvachillbilly]

Re: dont trust the mech.

There is no over rev alarm. If it is a solid tone you are overheating.

yes the alarm goes off when the engine over revs had the motor up too far in rough water one day prop came out of water and alarm went off and the mech said thats what caused the alarm oa his computer

 

[Knightgang]

Re: dont trust the mech.

When the prop come out of the water, it is not picking up water for the cooling system. I think your mech is full of it... JMHO

 

[hvachillbilly]

Re: dont trust the mech.

When the prop come out of the water, it is not picking up water for the cooling system. I think your mech is full of it... JMHO

ok cooling system appears to be working fine (good water flow out the pee hole anyway) will check actual temps of power head tomarrow could this be as simple as a bad overheat sensor?
when the prop came out cant rember if it was a solid tone or not

 

[hvachillbilly]

Re: dont trust the mech.

changed the thermostat this morning and i also put the 10pitch prop back on took for a run running 5800rpm for about ten min with no problem thanks guys jeffg i do apolagize i should learn not to be so bullheaded
now my question is why would a 11pitch drop my rpms to 5200 if a 10pitch lets the engine run at 6000 every thing ive read said that 1 degree of pitch will drop rpms about 200 is thes corect could the prop be marked wrong and not be an 11 degree pitch ????

 

[Jeff_G]

Re: dont trust the mech.

Pitch isn't the only determining factor. Diameter, material, blade design, over hub or thru hub, vent holes or not, and slippage all contribute to the actual rpms.
You may just have a very inefficient prop

 

[hvachillbilly]

Re: dont trust the mech.

i know both props are ss and 14" diameter not much more known what should i look for