fuel filter or water separator

[roffey]

Just thinking out loud here but I have a question for the masses. Keep in mind my boat is covered under warranty so I just may take it back to the dealer. OK, so here’s my problem. Up until last week my boat ran 5300 rpm at 55 MPH flat out. Now the max RPM is 4800 at 48 MPH. I was thinking bad gas up I filled up the tank with premium gas and went on a 20 mile trip and still no change.

Is there stuff I can check myself, I have a little mechanical experience but as the boat is so new it just may go back to the shop. Keep in mind this boat has 60 hours on it and was checked at 20 hours, I was thinking maybe a fuel filter or water separator maybe? Is there stuff I can check myself?

 

[H20Rat]

Same weight/number of people in the boat? Also hope you didn't hold it at WOT for that 20 mile trip. That is a long time to work that engine that hard! Very unlikely it is the fuel filter/separator, not the right symptoms.

 

[roffey]

I compared it with one person, me and half a tank of gas. No, did not hold it wide open, I find even at high 40's the boat is still a little to fast to keep it there. I like to cruse at 30-35 mpg with 3200 RPM for the most past.

 

[smokeonthewater]

My .02.... Contact the dealer and ask this question.... IE what do YOU want me to check before I bring it to you....

 

[smokeonthewater]

Make sure a spark plug wire didn't come loose.

 

[roffey]

I agree, I was in on Saturday and asked just that. They seemed to think it was bad gas. I'll run another tank full through and see if that helps. The boat is fast enough for me but if I paid for the extra performance I'd like to have it, LOL.

 

[roffey]

Here's what I'm thinking (dangerous for me). I week or two back I noticed the boat was down on oil, no problem I thought as this is a new boat and the motor is just settling in. I added some oil to bring it up to the middle of the has marks on the dip stick. I'm thinking maybe to much oil and I should keep it at the bottom of the marks?

 

[smokeonthewater]

Nope

 

[roffey]

Darn, lol. I'll keep trying..

 

[Maclin]

So, it is using oil? Maybe getting past the rings, indication of engine compression waning away and power loss. Take a look at the spar plugs.

 

[roffey]

Spar plugs, I don't think I know what they are or did you mean spark plugs? Keep in mind this is a brand new boat and motor and by low I mean it was near the bottom of the hash marks and I filled it to the top of the hash marks.

 

[Maclin]

Here you go, some assembly required... "k"

 

[roffey]

LOL, no assembly required just slap it on the end and away we go. Thanks I will check tomorrow and report back.

 

[roffey]

I checked the spark plug wires and all looks good, The motor runs like a top, except the most RPM I can get is 4900. Its almost like the prop is wrong but it is in perfect condition and has not been changed. I'm going to change the water separator and see what happens.

 

[cr2k]

Check the oil in your drive? Was the drive trimmed the same for all tests?'

 

[roffey]

hmm, I have a drive oil filler bottle in the engine compartment I check to make sure it is up to the line so I know I have gear oil. If I am doing a speed run I trim the motor up until I lose speed and gain RPM, start to cavitate. As I said I am going to change the gas filter tomorrow and see what happens.

 

[Alumarine]

Aren't maximum rpm's on the 4.3 4800?
Or are the newer ones higher?

 

[roffey]

I checked and the max is 4800, what makes me scratch my head is... I have a GPS application on my phone. It will track my rout and speed. My place is in a large bay that is normally glass calm and is about 3 miles long. I normally wind it out as fast as I can get it. I used to go 54 mph now I am at 50 mph. I thought for sure I was tacking about 5200. As I said the boat is brand new, 60 hours and I have never hit bottom so I know the prop is good. Just bugs me I have lost a few mph some where... LOL, maybe I should just let it go. Most likely there are more important things in the world to fret over..

 

[roffey]

new prop and top speed now 47.3 on GPS, lol going the wrong way. Next I am going to change the fuel filter, spark plugs and check for water in the tank. If that fails its back to the dealer.

 

[roffey]

I think I have it figured out.Believe it or not, I had a ants nest in my boat. The flame arrester was clogged from the stuff the ants dug out of the boat. I still can't figure how the nest even got started as my boat is wood free and spends most of the time on a boat lift so as near as I can figure they have to swim to shore, LOL.