Fuel Tank Issues

[CPO77]

Hi All, Im in the process of a gentle refurb on a 2015 8.5 Scorpion (rewire and repower) and looking for input or advice on anyone who is familiar with the tanks on these boats.
Ive had multiple RIBs all with either S/S or Aluminium tanks, most Scorpions have Derakane resin infused GRP tanks that are having some delamination issues on some older boats but according to Scorpion, this was addressed in 2009 via the tank curing process. Installed and cured properly, Derakane is highly resistant to corrosive liquids (including Ethanol ) and are still fitted to their new builds today without issues.

The boat is 2015 with 250hrs from new but not knowing how pedantic the previous owner was on looking after his fuel, I had the tanks pumped, flushed and cleaned and removed around 100L of old fuel. On visual inspection, the tank condition was clean and 100% sound with only a tiny amount of fine sediment in the bottom (which would be normal enough for a boat of this age).
I replaced all the fuel lines from the tank back with SAEJ30R9 hose and replaced the water separator with a Racor and filled it with 140L of fresh E5. I purposely didn't add stabiliser.

I ran the engine and the fresh fuel coming of of the clean tank is a darker colour that the fuel that's going in. I flushed the lines, drained the filter and primed then system and its the same. Ran the boat for 30mins and no change in the fuel colour in the inspection bowl in the separator.

Im genuinely stumped as even if there was an issue with the tank (i.e. worst case Derakane resin leeching into the fuel) this would surely happen over a period of time not within minutes of fresh fuel going in the tank.

Apologies for the long post but not overly happy about taking the boat offshore or repowering until I have got to the bottom of the fuel issues. Has anyone seen anything like this? Thanks all

[Peter_C]

Put some fuel into a glass and inspect it. The plastic bowls on fuel filters can quickly change color. Personally I am not a fan of having two more failure points on the fuel filter just to be able to see what is going on. I believe you could replace it with just a regular filter.

[gtflash]

I have a derekane tanked scorpion. I've also made repairs on grp tanks. There are vinylester reasons that once post cured are stable to most fuels. The ethanol impact is still unknown.

Scorpion switched to stainless but I think that's more to do with how they used the hull and stringers and tank "parts" rather than degradation. There are several scorpions reporting issues now but they are 1998-2001 generation.

in reality you have two choices.

Wait and see. Fit a good water fuel separator. A nice gauze filter and from time to time inspect for fibreglass, the red ish resin colour or water in fuel.

Dig up the old tank. Cut the deck and custom fit a stainless tank. Estimate £1500-2500.

Lots of scorpions and other boats with grp tanks still running fine. Try to fill up with low ethanol fuels and keep an eye on it if it's was me.

[wgc851]

Regarding fuel colour. I'm in the IOM so we only get E5 fuel here (for now) and no E10.
We've had this for a couple of years now where the fuel turns more of an orange colour, even after a short period of time, regardless of tank construction, mainly stainless and aluminium. This can also be witnessed on the spark plugs, particularity on lean burn engines. I'm not going to pretend to understand the chemistry behind it but it seems to be common, here at least
G

[Blizzard]

I have seen this before with new fuel hose, and the die comes out of the fuel hose for a short time.