excessive fuel consumption

[waynesworld]

Have got a 5.65 tinnie with a 115 yamaha on the back.Seems to me that it sucks down a lot of fuel.100 litres only lasts about 75 klms.Went from Raby Bay to Tanga and back and it almost all gone.Only sitting on 3800 rpms.Does any body else have this problem with this size motor?

[ballsie]

hey wayne, is the motor new or run in. a friend has a 6m c/c tinnie and put a foil on the leg and said it must be a perfect senario for the hydro foil as the fuel economy was significantly better, almost halved by memory. maybe talk to dealer about specs on the motor if not google your motor and check some on water tests that have been done. good luck ben

[Kerry]

....Only sitting on 3800 rpms....

I take it this is a 2 stroke 115 yammie? What size prop, what type of prop, what's the WOT rpm?

[Roughasguts]

Bit more information on the motor be helpfull.
She carby or EFI,?
What year model.?
She run rough at idle.? or hard to start.

And as Kerry asked what rev's do you get at wot, and what coresponding speed.

Thinking 3800 Rpm maybe a little low labouring up the motor hear, depending on the load you put in the boat. So how much gear.

Has it always been like this with fuel consumption.

[Cheech]

There would have to be something wrong. I get double that distance, and mine is 5.5 glass and a 19 year old 100hp 2 stroke.

[whiteman]

Sound like a big problem. Gotta assume a Saltwater series 2s and should get 1.3-1.8km/l. These work best from 4200-4800.

[No Tiller]

Happened to me years ago, the choke was partially locked on. Maybe maybe not.

[honda900]

waynesworld,

I have a yammie 130 on my Yalta 555HC 2006 model, which all up weighs in at a bit over 1 tonne, the 130 is the same spec as the 115 (assume bigger throttle bodies and carbs for the extra GG's), doing the same run as you from Raby Bay I roughly get 1.5 to 1.8kms per Ltr, without a permatrim. The engine has only done 35 Hours so is brand new.

On a real bad day offshore on the Gold Coast worst fuel consumption was 1km per litre and it wasn't very pleasant on that trip.:o

Regards
Honda

[waynesworld]

year model is 2004. Has only 47 hours on it.Most of my mates have dissappeared so very hard to get out and try different things to sort it out.Hey what is WOT?It's a two stroke by the way.

[Roughasguts]

Wot= Wide open throttle, flat out.

[newchum]

waynesworld
you must cheesed off with that economy, i have a 200 2st yamy on a 7m glass and at 4200 rpm (22knts) i still get 100klm out of 100lts.the motor sounds sweeter from 4000 to 4700.

[Roughasguts]

Could be half your problem there Wayne, to low in the Rev's.
Could be described as driving up hill in 5th gear with your foot almost flat on the floor. Not good for economy.

So maybe drop a size in prop, so what size prop has she at the moment?
Still need to know what max Rev's the motor will do.
And at what speed she gets too, for the guy's to make a decent comparrison.

[SunnyCoastMark]

Hey WW,
I would be checking your bilge for fuel under the floor (leaking tank /fitting or line).

Also check all fuel line hoses for splitting and or leaks.

I had a brand new 50hp Johnno with a split choke line once!:(

Check the position of your fuel tank breather - if they are to low (ie lower than or level with the tank) - you can lose a bit of fuel out there as well.

Process of elimination.....

Mark

[Greg P]

Has it always used this much or only recently ?

Check your prop for damage

1km/litre pretty average for Yammie 115 2stk

[Angla]

Have you taken it off the trailer or left the trailer on?

Seriously. Do you play with the throttle alot or do you just set it at a good cruising speed and forget it. The first method will use heaps more fuel and the second is more economical.

Hope you work it out

Chris

[bay_firey]

G'day Wayne
can't comment on your set up too much but I am running a 99 merc 115 2s on a 88 Seafarer viking and running at about 1.6 - 1.8 km per litre which I thought was a bit much

[waynesworld]

Yeh ANGLA I just put on 3800 then just sit there.It's done it since new.Only been on WOT for about 2hours in it's whole life..

[Roughasguts]

Wayne how fast you going at 3800 rpm?

[whiteman]

Yeh ANGLA I just put on 3800 then just sit there.It's done it since new.Only been on WOT for about 2hours in it's whole life..
Get it above 4000. That motor with a 17" prop (recommended size) will run to 5800 and maybe even 6000. With a 19" prop (like mine) you'll get it to around 5600 and my boat is screaming along at 35 knots and still getting 1.3l/km. Usually I'll get 1.7l/km at 4500.

You cannot kill this motor with a crowbar. Let it show off!

[honda900]

Waynesworld,

forgot to mention, I have a fuel flow meter on fitted which is integrated into the lowrance sounder, I find that around 4200 RPM with a 17 inch prop, I am getting about 44k's p/h and about 21 litres per Hour.

Sorry for the metrics...

[INTIMIDATOR]

When all else fail's:D
Unbolt anchor from rear , & attatch new 4 stroke::)
Problem solved!!!
Sorry! i'll go back to my corner now!:disappointed:
Cheer's anyway
Payney

[seatime]

Waynesworld,

forgot to mention, I have a fuel flow meter on fitted which is integrated into the lowrance sounder, I find that around 4200 RPM with a 17 inch prop, I am getting about 44k's p/h and about 21 litres per Hour.

Sorry for the metrics...

21lt/hr are you happy with that?

my Johnson 140hp 4st pushing a 6m tinnie (1100-1200kg depending on fuel & gear), by my calculations uses 10lt/hr cruising at 4-4200rpm with 2 adults onboard (extra 200kg with fish gear)
and about 18-20lt/hr constantly on/off the plane with 6-7 adults onboard (extra 600kg onboard).

I'm about to install a fuel flow meter to get more precise figures.

regards
Steve

[wrip109]

Wow! these big motors use a lot of fuel. I have a 14 foot AllyCraft and for the last 25 years it has had a 20 HP Merc on it (1982 model). I could troll for about 18 hours on a 20 litre tank of two stroke.

A few weeks ago the engine died(Suddenly) and I now have a brand new 30HP Yamaha two stroke. The fuel consumption has at least doubled and for the 50% increase in power I have increased the top speed from 18 knots to, a hardly huge, 21 knots.

Maybe it will run faster and use less fuel when it has been fully run-in OR maybe the old engines were better (?)

Phil

[seatime]

Wrip109, maybe it's a Yamaha thing ???
I had a 04' Mariner (Tohatsu) 30hp 2st on a 13' tinnie that returned figures like your Merc.

[TRD-70]

Bugger me, I have a 135 DI Evenrude and went for an extended 7 1/2 hrs constant at 3000-3500 travelling at a slow cruise and only spent $110 at the bouser.

[waynesworld]

My motor has the same prop on it as it came from the factory.Taking it back to dealer on Saturday.Hopefully they find a sticky float or something.If not I might have a fire sale ;) Thanks to you guys for your feed back gives me a few ideas now to try out when the handbrake lets me spend $150 in fuel for a drive in the bay.If you follow me you might be able to catch my fuel that I leave behind ;D

[TRD-70]

Mate good luck and hope all works out, get up the Yammy dealer!!!

[honda900]

21lt/hr are you happy with that?

my Johnson 140hp 4st pushing a 6m tinnie (1100-1200kg depending on fuel & gear), by my calculations uses 10lt/hr cruising at 4-4200rpm with 2 adults onboard (extra 200kg with fish gear)
and about 18-20lt/hr constantly on/off the plane with 6-7 adults onboard (extra 600kg onboard).

I'm about to install a fuel flow meter to get more precise figures.

regards
Steve


Steve,

I didnt really specify what I had in the boat but the boat is a glass boat, with about 3-4 blokes, weighing in (approx 400kg mark , bit on the modest side for one or 2 of em :-/ ) and the rest of the gear, interesting to see I get roughly the same fuel consumption as a 4 stroke, maybe a little more but not a great deal in it.

Keen to hear from anyone with a 150 etec for fuel consumption on a glass boat around the 5.5 - 6.0 meter range. Not to start a war of words, but for interest sake.

http://i98.photobucket.com/albums/l269/honda900_uw/Boat_Full.jpg

Regards
Honda

[leezor]

Honda,
As a comparison I have a 225hp Suzuki four stroke on a Southwind SF20. Last trip offshore covered nearly 100 miles in crappy conditions and put just over 90lt in it when I got back. Had 4 people on the boat, 2 adults, two teenage boys all our gear etc.
Conditions don't really seem to affect fuel consumption like it did with my old two stroke.

Cheers,

Lee

[honda900]

Lee,

thats pretty good for a bad day at 1.7km per litre, I get around that on a good day..

Regards
Honda

[marco]

a 150 etec on a 575 cc outsider gets 1.4-1.5 km/l on average

[whiteman]

Getting some remarkable fuel figures on this post. But I have to accept them as fishermen never exaggerate.

[leezor]

Getting some remarkable fuel figures on this post. But I have to accept them as fishermen never exaggerate.


The figures I mentioned where going by the distance covered on the GPS and the amount of juice pumped from the bowser to top the tank up after the trip, I am sure any Suzuki 4 stroke owner will be able to back these figures up ;D

[trueblue]

Check your engine height and throw away the crappy yammy prop...

Yammy's are often mounted way too low in the water due to their 'natural' cavitation tendencies. Also, the yammy props are shockers too, which also lends the motors to be mounted too low in the water increasing drag and making fuel efficiency worse.

I had to lift my 130 hp motor 2 inches from where it was originally fitted to get it to perform nicely with a new 17" pitch 4 blade Solas Prop.

Just changing the prop and motor height greatly improved fuel efficiency (haven't checked it exactly but it is heaps better) and I also improved top speed from 33 knots to 38 knots by the GPS at 5500 RPM. Thats probably a little over pitched, but the motor sounds sweet all through the rev range.

cheers

[Kerry]

What a load of tripe, nothing to do with yammie props and if you lifted yours 2 inches then obviously it was never set up right in the first place. Geez some people have some ridiculous excuses!

[trueblue]

What a load of tripe, nothing to do with yammie props and if you lifted yours 2 inches then obviously it was never set up right in the first place. Geez some people have some ridiculous excuses!

When I swap props from the solas back to the yammy prop performance goes back to crap, and I lose speed... the yammy prop slips like all buggery, and also breaks loose very badly at the higher motor position where the solas doesn't.

up yours too!!!

[leezor]

Ahhh Kerry, you certainly have a way with words - Dale Carnegie's book "How to win friends and influence people" is one you should consider reading.

[Kerry]

....up yours too!!!....
Nah mine's fine where they are thanks!

[Kerry]

Ahhh Kerry, you certainly have a way with words - Dale Carnegie's book "How to win friends and influence people" is one you should consider reading.

But then of course if one listens to the foil makers every boat/combination is a dog and needs a foil, all fuel has to have additives? well according to the people who make fuel additives, props the same nobody makes props like us as all other props are sh$t like when will people actually get back to first principles.

[trueblue]

and by the way, my yammy prop has cavitation pitting all along the back side of the blades.

[whiteman]

And mine (19" s/s Yammie) is fantastic from day 1. Well set up. Never heard of "a crappy Yammie" prop. 1st time for everything I guess.

[Luke G]

We got 25-27lt an hour with a 250 suzuki crusing at 4100 rpm or 26-28 knots. A bit better then the Ficht we had on there.

Cheers

[trueblue]

It is very interesting let me say, to change props from one brand to another, and see the performance of the boat alter so drastically that it is no longer recognisable in the ride as being the same boat. And that is without changing pitch or engine heights...

Then throw in the change in number of blades, and do height changes etc, and you would be amazed at how much diferently a boat could handle.

I thought my Yammy prop was great till I started experimenting with alternative props for the hell of it...

[Kerry]

You can talk up the Solas props all you like but Wayne's issue is not with props and Wayne doesn't need to spend a grand for a new Solas prop with regard his fuel issue.

Regards, Kerry.

[trueblue]

It's done it since new...

Kerry

Whats his problem?

The engine has been thirsty since new. Sounds like a set up problem...

I would definitely be looking at engine height, and pitch of the prop before anything else.

I'm certainly not trying to specifically talk up the solas props. A particular model suits my boat just dandy, and the Yammy prop is a guaranteed proven shocker on my boat.

If a yammy prop is a shocker on my boat, quite likely other boats could be having problems with them as well (several people I know have had this experience too...)

My Yamaha manual states to install the motor with the cav plate 2" below the keel of the boat. That creates a significant amount of unnecessary drag.

Plenty of people who have played with yammies for a while have found that the motors do tend to be fitted lower in the water than other motors particularly where the prop is not right for the boat and if there are ventilation / cavitation issues. [for the purpose of this comment just think about incorrect yammy prop pitch please]. And certain boats do have more issues than others.

If the motor is actually fitted too low, fuel consumption will be bad from the beginning.

Wayne... please show us a photo of the motor and keel from 90 degrees side on, and with the motor trimmed to have the cav plate parallel with the hull. Camera at the same height as the keel.

Also, we do need the wide open throttle rpm when trimmed out.

cheers

Mick

[backlash74]

hi i have 2000 model 115 yammy i average 1km per litre i thought thats not to bad just bought navman 2100 fuel flow meter hope to get better when i can what the flow rate still got to fit it i will let you know when i try it

[Kerry]

First we need to know the WOT max RPM and until we get that (and other details)then all the rest is pure speculation.

So when did Yamaha start spec'ing cav plates 2" below the hull? What motor is this?

If anybody knows anything about yammies or any outboard for that matter then they won't be fitting them 2" below the hull, simply not a standard setup.

First things first!

Regards, Kerry.

[trueblue]

mine is the 130 hp saltwater series. That what the manual states... shocking I know.

Mine was actually set up very close to the keel height against what the manual said, and I further raised it to be about 1 3/4" above the keel height. Now it runs sweet. Put the yammy prop on at that height and the prop breaks loose all of the time. 2" lower at the keel height shuts it up somewhat, but puts a lot of unnecessary drag on... And costs more fuel...

Boat is a Dale 5.3 (If you know what a Dale Boat is...)

cheers

[Kerry]

The saltwater series manual does not state 2" below the keel, that was absolute rubbish. The manual in now way says 2".

Dale? You asking me if I know what a Dale is :) So you got your own name above the door?

[trueblue]

Dale? You asking me if I know what a Dale is :) So you got your own name above the door?

Yeah, you know everything else so I expected you would know that Dale boats are an extremely solid custom built glass boat made in Home hill (NQ).

[disorderly]

Sorry guys,but I have to have a boast about the ETEC.
After getting about 2.2 to 2.3 kms to the litre with one or two blokes and all gear,I was pleasantly surprised to use only 49 litres to fill up last time after a 132 km trip.(About 10 percent at WOT)(2.7km per litre).
The engine might be just loosening up a bit after about 70 or so hours,whatever it is I cant complain about performance or fuel economy.
(90hp ,5.25 Stacer)

cheers Scott

Ps. No yamahas were dragged underwater in this particular test.

[mark221263]

a 150 etec on a 575 cc outsider gets 1.4-1.5 km/l on average
I thought you'd get better than this??? I've got a 150merc carby 2stroke on a 580 outsider and get 1.4klm/lt. Can be as good as 1.5 klm/lt on a smooth day and as bad as 1.15klm/lt in real rough stuff outside.
Cheers Mark