leaving fuel in underfloor tank

 Hi, have never had a boat with an underfloor tank but have one now, I have around half a tank (30 lt) of premium unleaded, sitting in my boat tank and have not been out in the boat for 5 weeks, but have ran the motor on rabbit ears in between, do I drain the tank if I am not going to use the boat for a while, or just top up with fuel next time I take the boat out?


Jackfrost80's picture

Posts: 4407

Date Joined: 07/05/12

You'll fine for a good 3-4

Sat, 2017-06-17 20:20

You'll fine for a good 3-4 months minimum in winter mate. Just top it up with fresh fuel before you head out next.

I had the same worry last year when I did my knee and rang the technicians at BP and Caltex and they both said their unleaded would be fine until 3-4 months and then start slowly losing octane and I should think about replacing it around 6 months.


If catching wrasse is cool, consider me Miles Davis

Posts: 72

Date Joined: 10/11/15

 Thanks mate :)

Sun, 2017-06-18 08:41

 Thanks mate :)

Posts: 566

Date Joined: 16/05/09

Keep your tank full to avoid

Sun, 2017-06-18 09:46

Keep your tank full to avoid any condensation.

Stevo81's picture

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Date Joined: 16/04/12


Sun, 2017-06-18 11:59



                                   ••••••••  Electrical Contractor NOR  ••••••••

Posts: 4828

Date Joined: 17/06/10

Spot on

Sun, 2017-06-18 16:13

You should always keep the tank topped up for exactly the reason Billcollector says minimum risk of condensation in the tank.