Yamaha 115 HP x 4 stroke outboards

[bandamamalta]

Gentlemen - I have just enrolled as a member of the Forum. I introduce myself as an avid offshore amateur fishermen from the Island of Malta in the Med.
I am the owner of a Seafox 26ft WA which I bought last year from the USA. This is powered by 2 x 115 Yamaha outboards ( 4 stroke) YOM 2005. I would like some expert assistance or recommendations on how to gauge the fuel consumption/MPG cos here gas is at $10 /gal!! Note that although I have an new 7 inch Lowrance HDS7 installed the engines do not take the NMEA2000 application, therefore the GPS is unable to receive any feedback. I am prepared to put in additional gauges if this is the case. Can anybody help me out pls. Thanks.

[robert graham]

The general rule regarding fuel consumption of outboard motors is about 10% of the HP rating per hour at wide open throttle. Maybe your 4 strokes do some better than that, but it would still be around 10 GPH per motor at wide open throttle, or 20 GPH for both motors. Check: Yamaha Outboard Performance Bulletins for additional fuel consumption information! $10/gallon!... guess we should stop complaining about $3.75! Good Luck!

[Triton II]

I have an 09 F115. It uses 40-41 litres per hour at WOT (about 34 kts) on my TABS Ocean Series 20ft cuddy cabin.



At 4000 rpm cruise (23 kts) it uses 22-23 litres per hour. At idle (700 rpm and about 4 kts) it uses 1.9-2.1 litres per hour. This is through my 6Y8 digital fuel gauge (Command Link).

I believe your motor will P&P with the 6Y8 gauges, but Rodbolt will be able to confirm that for sure.

Good luck, nice boat and nice part of the world for boating!

TII

[bandamamalta]

Thanks Robert & Triton 11 for your response. I have taken note of all that you have advised. I have in the past without any gauges ( galls put in tank divided by the miles covered in a day) worked out what the fuel consumption is/MPG and its about what both of you guys have stated...however what I am looking for is a set of gauges or some type of instrument that shows me what is being consumed/engine performance & gph while at sea. Triton11 - can yu pls. give me some details re the 6Y8 gauges by Rodbolt, maybe they will work..and your boat is real nice and well taken care of..best of luck to you too.

[rodbolt17]

the 6Y8 gauge package wont work on 05 and earlier engines.
there are a few manufactures that make flow meters for both single and twin applications but in the US they are in the 250 dollar and up range.
cant convert LPH to GPH well I can just dont feel like it .
Ill try to do some hunting on flow meters.
the Fuel Management set up from yamaha will work with your F115's.
its kinda pricy but its plug and play on your engine/control setup.

[99yam40]

Rodbolt,
if it was made in 2005 like he said could it still be a 2006 model, kind of like my old C40 TLRX motor where the Manufacture date was 04/98 but is a 1999 model?

[rodbolt17]

99
dunno
its an international market engine.
here in the US we dont get any information about them.
most of what I know about non US market engines is from working occasionally in venezuela.

[bandamamalta]

Thanks guys for all the info., very kind of you. Just to let you know that I bought not only the boat from the US but also the 2 x 115 Yamaha engines built in 2005.
I hope that in time some form of instrument is recommended showing what is the performance / fuel consumption...or Flow management gauges that Rodbolt has detiled, trusting that these are not too expensive!!

[rodbolt17]

need a model number if they are US market motors.
year of manufacture may NOT be the model year production run.
its possible to have an 06 model built in 05.

[bandamamalta]

Rodbolt - Thanks for trying your best to help out. You maybe correct with the YOM - the models are: F115TXRC - serial nos...68W 1001355 & 68V 1026787. Hope this info is useful, very kind of you to assist.

[99yam40]

Not sure what is going on because the C stands for 2004. Where did you come up with the YOM?

Yamaha Outboard Parts 2004 F115TXRC

[bandamamalta]

99yam40 - my sincere aplogies to all you guys who have shown interest in what I requested. I have just checked all, my records and yes 99yam40...you are very corrrect and sharp too so as to notice my error. The motors were manufactured in 2004 and not 2005 as I had stated initially. Sorry guys..but hope some member can come up with recommending an instrument/fuel managment system to follow the consumption/mpg. Thanks.

[boatmangc]

There is always the old Floscan..

Just make sure you have nice BIG fuel lines and no more than 3 90s in the system per motor )including the 90 at the tank and you should be fine.

[the viking]

Bandama Hi, my experience with the F115 - 2008 is in fresh water in the Paraná River Delta and the Rio de la Plata, the biggest waves here are 2.5mts nothing like the sea, but the current is sometimes higher 10 km / h.
I have the 3 gauge instruments 6y8, consumption plan depends heavily on the propeller and the weight, after many tests I stick with the 13x19 prop where consumer got the best value - RPM - end-reaction speed throttle - load.
A 3700 rpm consumption is 15 lts. / hour and the yield is 2.5km/lts.
A 4200 rpm consumption is 20 lts. / hour and the yield is 2.2km/lts.
Obviously in each boat varied and do not know if there are differences by having 2 motors, also in salt water resistance movement is different, but at 5700 RPM and 37 knots consumes nearly 35 liters per hour and the yield is 1.8 km liters approx.
I hope you serve the data.
My boat is 21 feet

[axolotl98]

You can always install a pair of the Lowrance EP-60R Fuel Flow Sensors in your fuel lines (one for each engine), which can be plugged through a Lowrance-net with your HDS-7 and show every fuel consumption detail you might wish to see !
You can also install a standalone Lowrance instrument LMF-200 or LMF 400 if you want to watch your fuel consumption on a separate instrument