Power's not what it used to be- Loose throttle cable?

[jxm99]

The boat's not producing power like she used. I know that she's gonna lose a little over the years. When i run WOT, around 4100rpm i feel like the boat could run harder, maybe get up to 44-4500. She used to get more but I'll give the old girl a break. could it possibly be the throttle cables have just loosened over time? Would a simple tightening or replacement give me more of the oomph i'm looking for?

 

[CliffA]

The boat's not producing power like she used. I know that she's gonna lose a little over the years. When i run WOT, around 4100rpm i feel like the boat could run harder, maybe get up to 44-4500. She used to get more but I'll give the old girl a break. could it possibly be the throttle cables have just loosened over time? Would a simple tightening or replacement give me more of the oomph i'm looking for?

just a guess but i would think that if the throttle cable stretched that much you would not be able to idle the engine at the correct rpm because the throttle arm would not return all the way back....

lots and lots of things can cause loss of performance over time....i am sure a search of the archives for 'power loss' in the 'Gas Engines' forum would yield lots of good reading for you....

cliff

 

[BillK2632]

Yeah, throttle / shift cables might stretch over time, but not enough to cause this. My 1999 has the original throttle cables and I just this year replaced the shift cable. Like Cliff said, if the cables were stretched / mis-adjusted that much, you would be having all kinds of shifting issues etc.

I would start looking at things like:

- Propellers, have they ever been reconditioned?
- Bottom growth, your in South Florida and a 320, I assume it's is in the water vs dry stored?
- Engine maintenance, tune up, how long since plugs, wires etc have been changed.

Age really should not have much to do with it, as long as it's been maintained and there are no mechanical issues, a 15yr old engine should be able to turn the specified rpms just like a new one.

 

[jxm99]

Yeah, throttle / shift cables might stretch over time, but not enough to cause this. My 1999 has the original throttle cables and I just this year replaced the shift cable. Like Cliff said, if the cables were stretched / mis-adjusted that much, you would be having all kinds of shifting issues etc.

I would start looking at things like:

- Propellers, have they ever been reconditioned?
- Bottom growth, your in South Florida and a 320, I assume it's is in the water vs dry stored?
- Engine maintenance, tune up, how long since plugs, wires etc have been changed.

Age really should not have much to do with it, as long as it's been maintained and there are no mechani
cal issues, a 15yr old engine should be able to turn the specified rpms just like a new one.

Bottom's clean although she does live in the water, props were checked and balance not too long ago, not sure on the plugs and wires. I'll check the logs. Mechanic does a good job logging everything. Thanks for the suggestions

 

[CliffA]

other things to cosider:
- how much weight is in the boat when testing WOT (# of people plus 'stuff')
- how much fuel in the tank
- how much fresh water on board
- how full is the waste holding tank
- how much wind that day
- is any of the canvas installed that could catch the wind
- what are the water conditions (choppy vs. smooth)
- were the trim tabs all the way up
- how old is the fuel
- any rope or line wrapped around a propshaft
- does the fuel have ethanol in it
- is the fuel the correct grade
- are the flame arresters clogged
- is the correct grade of engine oil being used
- are the fuel injectors clean and giving a good spray pattern
- do the injectors have the correct fuel pressure
- any restrictions in the fuel supply lines

these are just the things i thought of off the top of my head....as i stated earlier there are MANY things that can contribute to 'perceived' power loss if an engine does not reach its rated WOT rpm range....the engine may be performing just fine....maybe something else is keeping it from reaching the WOT rpm range....

cliff

 

[Jimmy Buoy]

If you're like me, you accumulate more "stuff" over time. My boat has things put away in dark little corners that haven't seen the light of day in years. That can really add a lot of weight that will reduce your top end over time.
A fellow boater just sold his boat last fall. Had it over 25yrs. The boat must have come up at least 2" after he unloaded all the personal items from it before the new owner took delivery. Amazing!