Boat slow

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
Hi everyone.
I have a probem I don't understand.
(20ft Panga, 5 yo, 1500 tropical hours, Yamaha 60 hp, hi thrust, 4 stroke.)
~The motor is starting fine, but a little slowly.
~It always runs fine, but the boat has been slowing down for a couple months.. now going at 25 mph, not 39 mph, as is normal.
~The huill is pretty clean. Certainly it's been much dirtier, without this happening.
~Usually, a dirty fuel filter stops it starting.
~It has several floor panels, which were made by glassing on top of ply panels, to flatten the V. These panels are rotten, wet, so heavy I guess.
But surely this would happen slowly , over time. (It would be a ***** to fix this without loads of work, if it's not the issue .)

So I'm at a loss to know what it is.. (no decent mechanics where live).

Injectors?

Thanks a lot for any advice. 😐
 

saltchuckmatt

Commander
Joined
Jul 19, 2019
Messages
2,566
Hi everyone.
I have a probem I don't understand.
(20ft Panga, 5 yo, 1500 tropical hours, Yamaha 60 hp, hi thrust, 4 stroke.)
~The motor is starting fine, but a little slowly.
~It always runs fine, but the boat has been slowing down for a couple months.. now going at 25 mph, not 39 mph, as is normal.
~The huill is pretty clean. Certainly it's been much dirtier, without this happening.
~Usually, a dirty fuel filter stops it starting.
~It has several floor panels, which were made by glassing on top of ply panels, to flatten the V. These panels are rotten, wet, so heavy I guess.
But surely this would happen slowly , over time. (It would be a ***** to fix this without loads of work, if it's not the issue .)

So I'm at a loss to know what it is.. (no decent mechanics where live).

Injectors?

Thanks a lot for any advice. 😐
20 ft Panga doing 39mph with a 60hp motor? I find that hard to believe.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
Well whatever the speed is or was, you can tell it’s a good bit slower…
My first guess is a plugged injector causing you to lose power on that cylinder. I’m guessing you have no tachometer to check your rpm’s?
 

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
Well whatever the speed is or was, you can tell it’s a good bit slower…
My first guess is a plugged injector causing you to lose power on that cylinder. I’m guessing you have no tachometer to check your rpm’s?
Tachometer died!
Would that get that way slowly, or suddenly, coz I've noticed nothing, and I use the boat all the time, so i I'm very attuned to any change?

I really can't get a mechanic here.. very remote island.. and I've done lots of repairs and maintenance on it, so can I check
what you say some other way?
 

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
Tachometer died!
Would that get that way slowly, or suddenly, coz I've noticed nothing, and I use the boat all the time, so i I'm very attuned to any change?

I really can't get a mechanic here.. very remote island.. and I've done lots of repairs and maintenance on it, so can I check
what you say some other way?
.. and thanks for respondíng!
Tachometer died!
Would that get that way slowly, or suddenly, coz I've noticed nothing, and I use the boat all the time, so i I'm very attuned to any change?

I really can't get a mechanic here.. very remote island.. and I've done lots of repairs and maintenance on it, so can I check
what you say some other way?
Thanks for responding Robert. 😊
 

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
Well whatever the speed is or was, you can tell it’s a good bit slower…
My first guess is a plugged injector causing you to lose power on that cylinder. I’m guessing you have no tachometer to check your rpm’s?
It's running smoothly.
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,333
I can go from late 60’s at start of season, down to barely achieving 60, just with the hull state.
But other than that…there are so many things that can scrub off speed on a boat. Also depends on variance shown by gauges too.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,340
Saying ASAP won't make us move any faster waiting for you to answer the questions.

What have you done for trouble shooting?

What is your compression numbers?

What is your fuel pressure?

What do your plugs look like?

What dis the contents of your fuel filter check reveal?
 

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
I live in a remote place.
There's a very sporadic signal.
I said ASAP because I wanted people to know I was not being in attentive, but doing my best.. which I am.

The plugs were renewed two months ago and look fine.
I can't run tests, check fuel pressure, compressions, because I'm not a mechanic and don't have the kit.

The fuel filter is clean. A dirty injector has been suggested.
Does injector cleaner additive work?
Can i check/clean then some lowtech way?
Thanks
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
Joined
Jul 23, 2011
Messages
49,340
No, there is no mechanic in a can

pulling the plugs and reading them will tell you if one cylinder is not getting fuel.
 

99yam40

Fleet Admiral
Joined
Sep 7, 2008
Messages
9,059
is there a way to drain the bilge?
maybe it has taken in water that is trapped down there making it heavy,since you have rotten wood down there
 

ppinny1

Cadet
Joined
Sep 18, 2010
Messages
17
is there a way to drain the bilge?
maybe it has taken in water that is trapped down there making it heavy,since you have rotten wood down there
I've cut a few holes. Not enough water down there TBH.Thanks you.
 

robert graham

Admiral
Joined
Apr 16, 2009
Messages
6,908
The injectors can be removed and mailed to an injector service that will test and clean each one and return to you by mail….You can research these services on line…..
 
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