why not to use old fuel?

[gustav]

hello all,(why not to use old fuel.)i have a 74 evinrude 6hp. i asked about this, and was told to get rid of my petrol out the tank from last year. <br />which i did. but when i was on the river some said it would of been alright. true or false?

 

[funpilot]

Re: why not to use old fuel?

here in the US, our fuels tend to be oxygeniated, with alcohol. The alcohol absorbs moisture, and crude starts to form, which can block the tiny passages and screw up your carbs.<br /><br />Since boat systems tend to have so little fuel in them, it is just safer to drain the tanks, run the fuel out of the carbs, or ad a stabilizer to the fuel.<br /><br />Less trouble. Preventive maintenance is one of those things which is hard to measure the benefit from, but if not done, and it comes around to bite your arse, it can be a pain.<br /><br />fp

 

[Paul Moir]

Re: why not to use old fuel?

Depends mostly on storage conditions, especially hea and how well sealed the tank is, and the original composision of the gasoline, but over time it'll turn bad and form gum and varnish deposits.<br />The big question is, is it worth running through a fuel sensitive engine like a 2-stroke outboard and risk engine damage. Personally, I'm a big believer in the sniff test, which is to say if it smells like gas, it must be still gas. But I'm prepared for the consequences of running old gas.<br />You can improve the gas by initially using a fuel stabilizer additive. Or by mixing some older gas with fresh gas.<br />EDIT: I posted at the same time funpilot did. Please don't take my comments as being in reaction to his. Pardon the collision, funpilot!

 

[funpilot]

Re: why not to use old fuel?

No prob... your post was better than mine anyway!

 

[petrolhead]

Re: why not to use old fuel?

I believe there is some difference between petrol in the UK and Europe, and that sold in the USA where it can even vary from state to state, but our petrol still has a relatively short "shelf life".<br />The higher elements in petrol, those that make it detonate easily and burn smoothly, evaporate quite quickly especially if it's stored in plastic containers. The aromatics can evaporate right through the plastic, metal tanks are better but the fuel still loses its potency with time.<br />The damp atmosphere that most boat fuel sits around in doesn't help matters either.<br />It's not always neccessary to dump the old fuel, adding fresh fuel (more fresh than stale) will make it useable, or just use it up a gallon at a time in your car every time you fill up.