Using aft reserve tank?

[boatingbob]

Hi Guys!

Question for you: I have a 1995 Carver 390 powered by Crusaders. This boat, like others in its size class, has a 125-gallon reserve fuel tank in the back, as well as the two 100-gallon tanks on the side. I don't know if this tank has ever been used, and I would like to use it next time I'm cruising in Canada, so I can take across the border as much of the cheaper American gas as I can hold.

The thing is, I'm a little reluctant because since the tank hasn't been used in a long time (if ever), I don't want to put a bunch of gas in there only to find it either (a) leaks, or (b) has guck in it.

So, my questions are:
1) Should I be concerned?
2) If I have reason, is there any way to check it before I use it?
3) Would it make sense to put in a small amount (10 - 20 gallons) and see what happens?

Thanks!

[Viper]

If it leaks and you put fuel in it, you'll smell like gas for some time, you'll have to pump out what you've put in, and you'll have some cleaning to do. You're best to pressure test the tank before putting fuel in it. To see if there's any solids in there that would pose a problem, you could probe the tank through the sender hole with a mechanic's inspection camera. This will also allow you to check the condition of the interior walls of the tank for corrosion. You could run an engine for a while off that tank with a fresh filter then see what the filter caught but you better hope the filter catches everything that might be in the tank or you could be creating engine runability problems.

[RGrew176]

I wonder why an owner of a boat with that type of set up for the tanks does not utilize the aft tank. If I were to ever purchase a new boat that had that type of set up I would make sure that I utilized all three tanks from day one just to keep that tank in the mix.

Is there some factor that makes it more difficult to utilize the aft tank?

[Viper]

Mechanically it works just as well as the mains. I suspect it gets underutilized because of the cost to fill and extra weight that adds.

[tomschauer]

Unfortunately these boats had problems with the aft tanks. If you show no fuel on the gauge, and you open the fill and don't smell fuel, I would guess there is a good chance it has failed and been "moth balled". As Viper mentioned you can have it pressure tested if you can get access to the top of the tank to disconnect all fill and vent lines. You only need a couple psi to test, see if it holds for 24 hrs or more, because, as I understand, some of these leaks are minute. If you do smell any fuel, I would be very cautious of using an inspection camera unless it is rated as explosion proof.

[boatingbob]

Hrm...it doesn't sound worth the trouble. The two guys I've talked to who have Carvers with this type of tank arrangement (another 390 CPMY and a 37' sedan) don't use the aft tanks. This is the first I've heard of those tanks failing.

[Midnightsun]

I would be careful as if it was never used for several years you may have a mess of varnish and bad gas in there.

That being said, I do have dual aft tanks on mine and make a habit of running fuel through them once a season to keep things fresh. Normally I function off of the 2 main tanks and only use the rear tanks if travelling far.

[buster53]

OK, quick question for you guys with the aft aux tank...

Can both engines be run from that tank at the same time?

[tomschauer]

I can run both engines from my single
aft tank.

[buster53]

I can run both engines from my single
aft tank.

At the same time?