I havnt been out for about 6 weeks.
last trip i topped up tank. 100 lit.
I used about 30 litres.
Will it be ok to just top up with unleaded or should i use premium if i go out over weekend.
Just worried about fuel sitting for 6 weeks
cheers
greg
I havnt been out for about 6 weeks.
last trip i topped up tank. 100 lit.
I used about 30 litres.
Will it be ok to just top up with unleaded or should i use premium if i go out over weekend.
Just worried about fuel sitting for 6 weeks
cheers
greg
greg, these days unleaded fuel does not go off that quick,just top back up with standard it will be fine, putting in premium will not lift the octane rating of the fuel you currently have as they will not mix together. cheers Lee
If you're worried, try a fuel conditioner ...
I have 4 20L Jerrys all lined up like soldiers, within a few days of the last trip I evacuate the tank into these. It seems this last couple of years the Jerrys have paid for themselves quite a few times over as i don't seem to get out much at all and who knows could have saved me a rebuild...I have seen a few ruined engines from old/bad fuel in my time.
cheers fnq
I think 6 weeks will not hurt it too much
I normally use 95 octane to be more sure there is no Ethanol in the blend.
Cheers
Chris
Hi, Yamaha produces a fuel stabilizer & conditioner that "Keeps fuel fresh and potent during prolonged storage up to 1 year. Prevents gum and varnish deposits. Draining fuel for storage is not necessary with the use of this product."
I use it in my generator which may sit for quite some time between uses as well as in my outboard to keep the fuel system clean. (Unfortunately, the outboard may sit for some time between uses also).
Regards. RTFM1000
Conditioners cannot refresh fuels and must be used on fresh fuel as it is added to the tank to get good results
There are different types from ones that create a "skin " ( not a actuall skin but a chemical one) barrier on the top surface that prevents evaporation of volatiles and those that mix through and attache themselves to various parts of teh fuels structure . Some are suitable for temperature change situations and others for where a moored boat is moving the fuel in the tank all the time. Some stop degredation and settling due to either hot or cold conditions.
Some conditioners are just a octane booster and that is not always a good thing especially if the motor it is being used with is under high loads like a outboard. Those octane boosters can free up varnish in carbs , melt hoses and cause all sorts of issues on older motors.
I would speak with the fuel company you buy fuel from, the motor manufacturer and ask them what one is suitable as I have seen issues with some imported ones designed for different countries. The fuel companies have conditioners that they add at production for transport , marina use and remote area fuels. Some are avaliable from them but possibly only in bulk.
what they say is add 10% new fuel should be fine
and where did you get the information that premium will not mix with normal fuel??????Originally Posted by lethal098
oh and 6 weeks is not old, it will be fine, top up with fresh normal or premium if you are worried, it will be fine
Adding fresh fuel to stale fuel is a recipe for problems.
As fuel breaks down it produces soem harmful oxides. These oxides cannot be counter-acted by adding fresh fuel. Its a myth!
Mercury claim that fuel begins to degrade within 2 weeks. By 8 weeks, its rubbish and should be discarded or cautiously used in your car (diluted) or in your lawn equipment (diluted).
Mixing premium fuel with stale fuel WILL increase the overall octane rating of the fuel, but that is really not relevant considering the harmful bi-products of the already degrading fuel.
Cheers
is stale fuel really much of an issue with modern "newer technology" 4 stroke motors? i mean, i've left fuel to sit for 12 or so weeks with my suzuki 4 stroker and the thing just started and went like a champion when i wanted to use it. i wouldn't know if there was some form of internal damage or additional wear caused by this but it certainly didn't seem to make much of a difference. i've now just bought my first ever mercruiser, it's an mpi model that's basically an automotive engine, i have never had an issue with stale fuel in my car so am expecting this one to be the same. pre-mixed 2 stroke fuel however, totally different story.
Yeah paddles stale fuel impacts the valves usually gunking the stem up or in worst case scenarios burning them out. Your car has a more or less closed fuel circuit boats do not, this is a mojor part of the riddle that many forget when the state how long fuel lasts...dontthink of a jerrycan withthe cap up tight think of one that is missing it's cap, then give an estimation of Time versus Quality.
Hey congrats on your new engine hope there is a boat with it.
I was not long ago very interested to see what was going to be the upshot of the "unleash the beast" segment on a TV fishing show, they swapped out a mercruiser in a 23 bertram for a 350 v8 yamaha.
Outside of all the marketing ...the upshot without the marketing just the graphs showed that in nearly all areas except for noise the mercruiser was fully or very nearly a match for the V8.
All this was after the first run where they bagged the daylights out of the mercruiser, then they proceeded to fit an engine to this style of boat that although greatly quieter also lived up to the same bagiing but never got it.
We haven't actually come a great deal further it seems.
cheers fnq
Hey, I've got some questions:
- Will fuel stay fresher longer if a tap is installed on the (underfloor) tank breather so it can be closed off when not in use?
- will a full tank (no air layer above) stay fresher then a partially full tank?
cheers
Just on the non-technical record, I left my 115hp Merc sitting for well over 6 months three quartres full before I sold the boat, and I was really worried about her starting. But she started straight up and ran like a train. On a technical note though I know it's not good practice at all.
Yes but i wouldn't do it, the potential pressure build-up with minimal fuel in it might surpass the tank and connections original design.
You could fit a valve in line with the breather but then again it could get blocked.
and
Yes full tank is the way to go for 2 reasons, it decreases the available surface area for the fuels volatiles to flash away and it increases the mass of fuel to help starve of temperature extremes which in turn increases volatiles escaping as well as oxidation of the fuel.
Full tank and some conditioner is the way to go over any 8 week period if you must.
cheers fnq
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