60hp 3 cyl yammy heavy on fuel

[Toniwdsl]

hi guys <br /><br />what is the average fuel consumption of these motors. i change from 60hp 2 cyl to 60 3 cyl. the 2cyl gave me about 15 lph .. are these 3 cyl so fuelish or is something wrong. the 60 trips is 1993 models and runs very well and is really quiet

 

[Anymec]

Re: 60hp 3 cyl yammy heavy on fuel

Max. fuel consumption for the 60F is 23L/h.

 

[Braxton]

Re: 60hp 3 cyl yammy heavy on fuel

im not sure but i have 3 carbs also, i'll be watching your post so i can learn about it also. so im no help.

 

[Toniwdsl]

Re: 60hp 3 cyl yammy heavy on fuel

Thefin thanx ... then i guess it might be wise to have em both checked coz running at about 25 kph for about 20 k's they chowed 60 litres of fuel... cant undrstand why they should be so heavy on fuel tho coz my 60hp 2cyl only used 20 litres per hout together. that means the 3cyl use twice as much fuel than the 2cyl 60s?? but thanx anyway ... will post back if i find anything wrong with them

 

[jim dozier]

Re: 60hp 3 cyl yammy heavy on fuel

How is the 3 cylinder running? If you had a hole in the fuel pump diaphragm you might be injecting excess fuel into the intake port of the cylinder to which the pump is attached. Usually makes for a poor idle but might not be so noticible at WOT. Pull the plugs and compare them. Also if you have a bad cylinder the engine will have to be run at a higher throttle setting to compensate causing poor fuel mileage. I would not think that a 3 cylinder engine that was running correctly would have dramatically different fuel consumption. Other items to check<br />- is the engine height correct?<br />- Is the engine propped correctly and is the engine turning the proper rpm at WOT? An engine that was over- or under-propped might use more fuel than necessary.<br />I think you have a problem you just haven't found yet.

 

[Toniwdsl]

Re: 60hp 3 cyl yammy heavy on fuel

jimd <br /> <br />thanx for ur input ... will check coz the one motor appears to be running a lil rough at certain speeds. the height is fine and trim is ok. will go thru the other points u mentioned ....these motors use the 85 yamaha props that originally came with them since new and previous owner also says they should not be using so much fuel.. anyway ...thanx again .... will check and get back

 

[ivar]

Re: 60hp 3 cyl yammy heavy on fuel

85HP yamaha prop = 13 1/4x17 if I remember correctly , suitable for a 16-17ft boat. What kind of boat do you have, and how heavy is it?

 

[Toniwdsl]

Re: 60hp 3 cyl yammy heavy on fuel

ivar<br /><br />yip u absolutely correct my boats a 5.7m robcraft she weighs about 500 kilos without the motors .. in fact even 40hp motors easily puts her on a plane. I decided to take her to sea with each motor on a seperate tank to see which one of them might be the culprit. i have one question tho ... the one motor's prop appear to have black residue on it ( like black soot ) does that mean something ?

 

[Triton II]

Re: 60hp 3 cyl yammy heavy on fuel

If there's a distinct difference in the amount of carbon build up (the black soot) between props it could mean one motor is running richer than the other. Whether it's running too rich is what you can establish from a fuel consumption test on each motor in turn. Do this at idle, 2000, 4000 and WOT. Should be a fairly even graph something like 10L per hour at idle, 13 at 2000, 23 at 4000 and about 30 at WOT. My 60 four-stroke uses 23L per hour at WOT and I think the 60 two stroke uses a fair bit more hence my approximate figures.

 

[Toniwdsl]

Re: 60hp 3 cyl yammy heavy on fuel

ok thanks guys for all the help .. had both motors checked seems thats the specs of these motors .....best thing i shud do now is maybe change em for 50's or fit a bigger tank.. and dont lose that awesome thrust...well triton like u said ..........Broker but happier !! ..

 

[Triton II]

Re: 60hp 3 cyl yammy heavy on fuel

Great, glad you got a result!