Fuel Consumption Suzuki 225 Four Stroke

[adams1x]

Hi,

I recently installed the Suzuki engine interface to Chartplotter and have fallen foul to the issue where it give the wrong data... I am on the case with that but wondered if my actual fuel consumption sounds high.

The previous owner had the injectors cleaned a couple of years ago as it started using a lot more fuel and it might be in my head but think it is doing the same, that or the gauge reading 40 ptrs and hour at idle has addled my brain!

The boat is Cobra 755 with Suzuki 250 - Filled to brim with 260 Ltrs of fuel, 2 people up and about 25 litres of water and various bits of kit

I did the following trips from the Hamble before refuelling

1. 20 Min running time trip - 3.1NM
Hamble to Southampton Water potter out at 6 knots then play between 20-35 knots and back in - Flat water

2. 40 Min running time - 11NM
Hamble to Cowes and Back, force 5 seas, cruising at about 20 - 25knots

3. 35 mins running time - 3.5NM
Hamble to entrance of southampton water at 25 knots with 1 or 2 mins at 40 knots then potter back slowly at 4-5 knots alongside sailing boat!

Total fuel 47Ltrs and distance covered 17NM

Based on that i wouldn't even make it across the channel :-(

Does it seem high to you all?

[adams1x]

Just thought, don't know if this is related but it starts quite badly and often I need to give it some neutral revs to get it to start, better cold than warm.. once running it sounds perfect and very smooth

[Xk59D]

Please search for topic. You need to firmware flash the suzuki cable to get accurate readings

[jeffstevens763@g]

86.2 Lt/ hour WOT based on that I would say yes

[adams1x]

I mentioned I know about the firmware issue and am on the case and should have a Lowrance HDS unit next week to connect to downgrade to 2.3 but my question was an actual fuel consumption issue not what the guage reads... that says I have done about 400 litres in that time!

[Xk59D]

Fimware flash it, you are using too much yes.

Or do it the proper way and brim it after a run.

[adams1x]

Thats why I need the HDS unit, you can't do it from Raymarine stuff! So annoying!

I did the brim to brim thing.. thats how I know the 47 ltrs - that was not from the chartplotter that was actual fuel used for those trips.

Oh Joy, so looks like I have an issue that needs to be fixed as it is costing me too much to run and fixing it will also probably cost too much too.. Got to love boats :-)

[Poly]

Originally Posted by Xk59D

Fimware flash it, you are using too much yes.

Or do it the proper way and brim it after a run.

But Xk59D that is what the OP says he did to get his 47 L figure (after 17 NM).

It does *seem* high. But then very simply a 250HP engine is going to burn a lot of fuel. At wide open throttle you might expect the engine to burn something like 80-100L/hr. At cruising speed perhaps 1/2 that. All that time at lowish speed isn't necessarily more efficient either if you are half on the plane you are driving up hill for nothing.

You are using just under 30L/hr which doesn't sound too bad...

[adams1x]

Thanks Poly... Think I might have a nice cruising run down the solent for an hour or two to give me a proper figure...(guess if i run out of fuel that answers the question!)

Hopefully it is just knowing there was an issue in the past means I am over thinking it..

[Xk59D]

My 200 burns 0.9l per statute mile if that is of any use as a guide ish.

[adams1x]

Ok, thats perfect and think gives the knowledge I have an issue although going to do a 20-30 mile run tomorrow morning and get some breakfast in yarmouth and run back to give me a definitive answer.... Full English or Bacon roll depending on the gauge when I arrive!

[willk]

2.7L/Nm is the sort of return I was getting running 2 x 300HP Suzukis over 250 miles on a lad's weekend in Scotland on a 10m RIB.

You have a problem or the fuel barge is taking the p1ss...

[adams1x]

Probably both!! Do people think the injectors would be the first place to start in the investigation?

[willk]

I'd consider leaks too!

[adams1x]

More and more worries!!!

[jonp]

I find this fuel calculator pretty accurate, I normally use it in littles but have clicked for gallons at the top of the page.http://www.boat-fuel-economy.com/suz...perial-gallons

Jon

[adams1x]

Thats great and interesting, My cruise RPM at 25 knots is usually around 3500 to 4000 and that is doing upto 35 ltrs and hour... Then add the messing around bits, up and on the plane a few times as was messing around with another boat at one point, few circles and playtime Im not sure I am a million miles out but the longer trip to the needles this morning only happened in my mind as couldn't wake up! Another day to do a proper test!

The engine revs to 6000 within range but on the end, so another consideration might be to replace prop and pitch down a little to reduce RPM and help with Fuel?

[Poly]

its also worth considering whether "filled to the brim" is the same before and after. Slight changes in angle (e.g. people one board) can make a big difference to the size of any air pocket trapped in the tank.

[adams1x]

True on the brim comment although the first time was on trailer and took ages to make sure it was full and second time on marina berth.. sadly think it is more likely less fuel in the second fill up!

[Erin]

My 200 cruises at about 1.0 to 1.1 l/nm. At the least inefficient I get about 1.7 but that would be just before getting on the plane. I think a 17 mile trip is a bit too little to accurately calculate consumption. Certainly worth a longer trip and at more constant speed.

Calibrating the lowrance software is a bit of a pain but does end up quite accurate if you do it properly. There is a guide on the net somewhere about which .luf file to use. Don't upgrade just for the sake of it as that can cause more problems than it solves.