Information on 1988 24 Offshore fuel tanks


New Member
Jul 8, 2019
Grady White Model
Bought the boat back in Nov. I have a Main tank and a aux tank. It has 2 outboard Mercury's 200s. Was at lake this weekend and I had both tanks set to main tank. I ran out of gas on one motor and the other kept running. I think I was really low on fuel. I was also testing the gages which I think I'm more confused now. Anyway I have a fuel filter on each line. The motor running had fuel in filter the other was dry. I put gas in main tank couldn't get it to prime so I added fuel to aux. Well after trouble shooting I found it takes a few turns of the switch to prime and pimp ball. I got motor primed and back running. I've also noticed that if I fill up both tanks and run just main fuel tank when I fill up again the aux takes a reasonable amount of fuel 15-20 gallons. Anyone experienced this?

I have not taken up floor because the tanks where cleaned and flushed 1 year ago with new lines, no fuel is coming out of boat when I pull drain pull. Could the tanks be connected or could the valve be bad where I'm switching tanks. Any help is appreciated.

Uncle Joe

Well-Known Member
Aug 15, 2017
I have run a few older Offshores and while I have not had your exact problem I have had a few different issues related to fuel tanks and hoses.

First off I would absolutely lift the deck plates and inspect tanks and hoses. It is not a big deal to do and I have had corroded tanks leaking fuel into the bilge and dry rotted/cracked filler hoses on both my Offshores.....all this is to be expected after 30 years or so. Filler hoses are a bit of a bitch to replace and not cheap but well worth the effort.

You may be sucking wind in one or both of your fuel lines back to the engines....these lines are very easily replaced once you lift the deck plates.

I have a manual diverter switch to change from main to aux tanks......if you have one they are cheap and easily replaced as well.

In short I would say get in there....inspect all tanks/hoses/and switches....including vent hoses etc.

I hope this helps.