Iíve realised I have an issue with the installation of the 225Opti on my Ocean RIB which Iím very near to completion after many delays and false starts.
Mercury recommend a minimum of 5/16in (8mm) ID Fuel hose, but Iíve discovered the pick-up pipe welded in to my fitted 120l under-deck Stainless tank is only @5mm ID.
I never did notice a fuel starvation issue with my old DT200EFI, but then didnít ever hold it at WOT for more than a few seconds at a time.
The boat was originally rigged with a Johnson 150VRO before I brought it, which drank petrol at an alarming rate, so Iím surprised.
I know for my use of the boat the existing pick-up pipe will probably be fine, but whilst Iím replacing all hoses and doing lots of other work I may as well put something bigger in.
However, the tank is obviously under the deck, with very little of it accessible, and I donít really want to start drilling holes in and welding a tank 1/3 full of fuel, let alone cut up any of the deck to reach it, even within the jockey seats.
So I have a plan, but am wondering what sort of gap I should leave between the end of the pick-up pipe and the bottom of the tank?
NOTE:- The following are all really old images, but I donít want to uncover the boat and take new ones in the pouring rain we have today.
The deck is laid out as below:
The tank stretches across under the deck almost the complete width of both Jockey seats, and the small round hatch between the jockeys covers where the fuel gauge sender once lived:
Note I gave up using fuel gauges years ago, so there is currently a plain round stainless plate screwed down to the tank over the hole.
I now use a Navman fuel computer flow sender and gauge with careful measurement of what goes in the tank volume wise.
Inside the port Jockey seat are the various connections to the tank.
Since this image was taken Iíve removed the rectangular plate revealing a hole in the deck just a little smaller than the plate, and have Flowcoated the inside of the jockey. Did it years ago.
From top to bottom:
Conduit to Transom area.
My plan is to cap off the existing pick-up pipe, and put a larger one in using the old sender mounting hole.
Iíd need to have a right-angle fitting on top of the new plate that I could attach a new fuel hose to, which would then pass across the top of the tank and into the Jockey seat alongside the original pick-up pipe.
An added advantage is that being removable Iíll be able to add some kind of first stage filter to the bottom of the new pick-up pipe.
I hope this makes sense, new pipe/hose in Red:
But as mentioned, my question, after all of the above, is what gap to leave between the bottom of the new pipe and the bottom of the tank?
I obviously donít want to suck up any crap in the tank, but also donít want to lose too much useable volume.