Engine drinking way too much fuel for my liking

[Solent Bombard]

I currently have a 135 V6 on my rib and although I knew it would drink the fuel at WOT I thought it may be more frugal at a slower speed.

Went to yarmouth from calshot last Sunday and back just at a nice steady pace of the region of 20kts and ended up using about 50 litres of fuel with 2 adults and a dog.

Boats in general are not cheap things to run but I was hoping for better consumption than I have currently.

Especially as the fuel tank on board my boat will not allow me to go much further than yarmouth without running out of fuel.

Would a smaller engine I.e 100hp or 115hp be really that much better or are all engines just absolute abysmal on consumption.

And should I just accept being skint if I want to run the boat

[Nick Hearne]

Something not right say you did 25 miles that's 2lt per mile you should be getting better than that, what is the engine?

[jambo]

I have a 150 v6 and on a good day I'll burn 1.1 ltrs per mile but if it toughs up it does go up can jump up considerably depending on throttling.


Sent from my iPhone using RIB Net

[Trimix]

Mmmm, I did a trip round the IOW which ranged from a pootle into Cowes and Yarmouth and some WOT messing about. Ive got twin 175's on the back and did about 1.4km per ltrs.

Did you leave the anchor down

[Trimix]

On a more serious note - wouldnt the trim affect it a lot ?

[jambo]

What's your hull like. If it's bad dirty that'll cos extra burn


Sent from my iPhone using RIB Net

[paddlers]

I have a 135 Mariner V6 on my 17ft hardboat, At 5500 rpm you can watch the petrol gauge move, when cruising at 3500 it lasts slightly longer....

I love the sound and acceleration but can do the tank (50 litres) in an afternoons skiing and general bobbing about. Did a 25 mile run from Carradale to Campbeltown and back one morning with the family and emptied the tank which also made me think 2 litres a mile at WOT !!

Had a 115 on it previously but lacked the grin factor! But fuel went further.....

[Searider]

have the carbs been serviced and set up correctly?

[Bigtalljv]

i sure am glad we use gallons over here. My 7m with a 250 does about 3mpg or 1.13L/mile!! at 36mph.

[Solent Bombard]

Originally Posted by paddlers

I have a 135 Mariner V6 on my 17ft hardboat, At 5500 rpm you can watch the petrol gauge move, when cruising at 3500 it lasts slightly longer....

I love the sound and acceleration but can do the tank (50 litres) in an afternoons skiing and general bobbing about. Did a 25 mile run from Carradale to Campbeltown and back one morning with the family and emptied the tank which also made me think 2 litres a mile at WOT !!

Had a 115 on it previously but lacked the grin factor! But fuel went further.....

At WOT I would expect it to probably do 2 lts per mile but on Sunday we were doing mid 20's if I went WOT I reckon I'd get 50kts as she does mid 40's with a lot more to go on the throttle.

[Solent Bombard]

Originally Posted by jambo

What's your hull like. If it's bad dirty that'll cos extra burn


Sent from my iPhone using RIB Net

Hull is shiny clean and kept on trailer out of the water

The dog modelling the hull while hiding in the shade

[paddlers]

By simple maths I'd expect the fuel consumption to roughly half at half the revs. My outfit with nobody in it weighs in at @750 kilos so with my 18 stone plus the wife & three kids we're a fair weight.
Have you had it into a GOOD service establishment to have it looked over ?

[Solent Bombard]

Went in dave crawfords at lymington for a service but due to one of the voltage regulators bursting into flames it only got a fuel pump rebuild and regulators changed.
They said it looked so clean that they reckoned the carbs were nice and clean.

Keep meaning when I got out to put the quicksilver quikleen through it by adding to fuel but keep forgetting.

[Searider]

Originally Posted by Solent Bombard

Went in dave crawfords at lymington for a service but due to one of the voltage regulators bursting into flames it only got a fuel pump rebuild and regulators changed.
They said it looked so clean that they reckoned the carbs were nice and clean.

Keep meaning when I got out to put the quicksilver quikleen through it by adding to fuel but keep forgetting.

May "look clean" but have they been set up and balanced?

Compressions all even?

[paddlers]

There'll be a way to make it run leaner by adjustment on the carbs but I've no idea how to advise you to do that.

Sorry.

[Davie]

Take the six drain drain screws out the bottom of the carbs one at a time and check that a main jet has not fallen out one of them. Punctured float? Dickie needle valve? Fuel pump diaphram?

[nugent]

Run loads of these lumps and there better than that normally

Check as Davies said,,

[Solent Bombard]

Originally Posted by Searider

May "look clean" but have they been set up and balanced?

Compressions all even?

Compression on 6 cylinders were all around 120psi carbs look all to be running good but not had them cleaned thoroughly yet.

Here's a short video of the trip on Sunday I just video'ed the engine while running to check if the engine height was good it looks reasonable nice and clean out the back end

https://www.youtube.com/watch?v=-MaSA7wHgVA

[paddlers]

Had a few issues with mine until it took a battering on the beach which seemed to shake the crap about in the carbs and it flew afterwards and that has given me the excuse to clean them. I drained them initially & it didn't help.

Any good tips on how to make sure I do it right?

I hope this isn't a thread hijack...

[paddlers]

Just watched a 3 part youtube of a guy stripping down V6 carbs. Is it necessary to do a complete strip or will removing the float bowl and giving it a good blow with the airline do ?