Do I have enough horsepower?

[donnymac]

2006 Campion cuddy cabin, 19'. Fuel injected 4.3 volvo 2800lbs. 14.5X19 propeller. The boat now has about 40 hours on it. When new I waited the 10 hours before WOT. With the 19 pitch prop it pulled 4300rpm.(engine sticker and manual say 4400 to 4800) So 4300 was about good enough for me to get to the fishing spots(I like cruising at 2900 which gives me 32mph), but I bought a 17 pitch for the summer sports. so last summer I put the 17 pitch on and got 4600rpm by myself. Everything is fine. Last month I felt like going fast so I thought I'd bring it up to WOT. With the 17pitch on it only spun 4000rpm. Just for giggles, today I put the 19 pitch back on and it spun 3700 rpm.(Could have guessed that one)
The engine has fresh plugs, oil, fuel filter and leg oil. The last inexpensive thing I can do is have the tach checked for accuracy. Any other ideas?

Thanks
Don

 

[oops!]

Re: Do I have enough horsepower?

welcome to i boats

thats weird....

is there fresh fuel?

if its last seasons fuel...
it can go flat.

cheers
oops

 

[Arima90]

Re: Do I have enough horsepower?

With my 1988 I/O 5.0 Liter OMC Cobra, she would drop in power when the fuel was only a couple of months old. Since the engine is relatively new, bad fuel would be my guess. I would also check timing.

 

[QC]

Re: Do I have enough horsepower?

I always want to know about the tach, but it should not have changed unless you were playing with the switch on the back for 4, 6 or 8 cylinders . . .

Where do you boat? Is the boat trailered? Is the bottom clean? Here is the Merc low WOT diagnostic info (thanks DonS). Remember, if she once had "enough power" then she still should if all is right . . .

Also look at number 2 in the list. If she had the right pitch once it should still be the right pitch.
This is more of an engine discussion than a prop discussion . . .

 

[donnymac]

Re: Do I have enough horsepower?

Good thinking guys, thanks. I thought about and remembered I put about a 100 bucks in (89 octane land based fuel station)at around the end of September, no wait the end of October, darn, can't remember. Well there's a little less than half a tank, so I should be able to squeeze another 100 bucks in and try again on the weekend. Thanks again.

Don

 

[Frank Acampora]

Re: Do I have enough horsepower?

Check for a partially or fully clogged fuel filter. If you mixed land and marine fuel, you may have developed the "GOO" --Jelly like substance that clogs filters, pick-ups, and carbs. Happens when gasoline containing ethanol (land) is mixed with gas containing MTBE (marine) in a moist environment. See if you can still find the WAWA pamphlet (here on the East Coast.) It had a quite nice but concise explanation of the problem.

 

[donnymac]

Re: Do I have enough horsepower?

Fresh filters everywhere. I might actually have to break down and pay somebody to have a look at #9 on the list.
Cheers

 

[MikDee]

Re: Do I have enough horsepower?

You might want to check out the antisiphon valve, & fuel line filter in the tank.

 

[donnymac]

Re: Do I have enough horsepower?

Well the shop figured it out. The Faria tach isn't reading properly. I've never even seen the back of it, but the mehanic assures me that it's on the right setting anyway. The tach's about 800rpm out. Good thing there's a rev limiter So thanks for all the ideas and now I can turn this post into a propeller debate like it should have been in the first place. The 14 1/2"X19 pitch prop turns a sweet 4700rpm with two people. I've heard to pitch down when changing to stainless(mine's aluminum) If I mail order the new prop I might only get 1 shot(and/or a lot of hassle) so...... 18 pitch or 17. The Solas HR Titan 4 blade with the 17 pitch looks good.
Thanks again!
Don

 

[QC]

Re: Do I have enough horsepower?

Well I am surprised my first hunch was correct. Didn't really sound like it, but in fact we all got kinda lazy and didn't think this thru . . . We should've asked what your speed was now, but we all took off and started guessing. Good thing it worked out relatively cheaply (I hope) . . .

 

[donnymac]

Re: Do I have enough horsepower?

Yes, the back of the Faria tachometer has a small hole that you can insert a 5/64 allen key and fine tune. Who knew. Thanks for all the help. It's good to get to know your boat better.

Don