In-tank w/ in-line pump question

[Capp]

Hey folks--
Who among us has done the ADDITION of an in-tank electric fuel pump ('77 thru '94 Spider?) to work in conjunction with the in-line two-port electric pump as fitted to '70's Spider and GTV-- SPICA cars? This modification is recommended when doing a TwinSpark motor swap and It makes sense if you think about what is current practice among mfgrs. The in-tank pump assures that the main pump and/or fuel rail sees full pressure regardless of fuel tank level (pressure head) and whatever cornering/stopping forces are encountered. Since I'm not familiar with the sending unit/in-line pump of the L-jet cars, I'm having trouble visualizing the plumbing diagram for such a setup. Also, will this later style sending unit/pump fit in my GTV fuel tank without major modification or fabrication? Anyone here BTDT?

[Lanciahf]

I have all of the parts for such a project, but I am waiting for the spring thaw to happen.

My car is a 74 GTV that I'll attempt the conversion on.

Jim Steck said a fuel sender from an eighties spider will fit.

Good luck,
Ralph

[axis_powers]

If I read your post correctly my spider has that factory. Late '79 in tank pump with a 2 port in line bosch pump and spica. Just refurbished the entire system.

My interpretation is the in tank pump helps build pressure for the newer style gas tanks that have their output at the top of tank as opposed to the bottom of the tank in earlier models. This would support your head pressure philosphy by having pressure at the main pump.

I have never found a factory document supporting my setup, of course that is meaningless....... as Alfa made changes that were not always documented and my car is a late '79 build.

will this set-up fit your tank? Not sure, but I will be willing to measure the length of the pump setup in the tank if it can help you.

[papajam]

I believe that in 1977, Alfa switched the fuel supply pump feed from the bottom of the tank to the top. It was later discovered that, because the supply pump was designed to push fuel and not pull it, that the pump could starve for fuel under certain conditions with a low fuel level in the tank. So Alfa retrofitted intank pumps to feed the main pump in certain 77, 78 & 79 Spiders. Alfa fitted intank pumps from the factory starting in, I think, 1980.
I'm shooting from the hip here but I'd think that the only 'major' modification would be running a hard line from the top of the new sending unit/fuel pump assembly thru the floor of the trunk.

[Capp]

So... it sounds like what I need to do is: 1) block off the original large diam. outlet at the bottom of the tank, 2) insert the new-style pump/sender in place of the old sender, 3) plumb the outlet of the new pump through the trunk wall down to inlet of original in-line pump. This assumes the flange diam. and mounting bolt spacing is the same on old and new style senders, and that the overall height of them is approx. the same-- I know there are differences between Spider and GTV fuel tanks. As I have already relocated the battery to right rear of the trunk and have put the existing pump on a fused relay, it sounds like a simple matter to add an additional relay/ fuse for the other pump. Other than making the proper hose adapter to accomodate the different diameters of pump outlet/ inlet, what am I forgetting? Thanks guys-- it's always reassuring to see the collective experience and knowlege of this group.

[Lanciahf]

What battery tray did you use to relocated the battery to right rear of the trunk.

How many feet of battery cable and where did you get it?

Any Pictures?

Thanks,
Ralph

[Capp]

Ralph--
I decided after considerable research and some firsthand experience w/ motorcycles to go with an ODYSSEY battery which is encased in metal--no need for a box. One thing less to deal with in order to service or disconnect the battery. It's location on the back "shelf" of the trunk makes it somewhat hard to get to, and putting it in a box would make it a real PITA. I also liked the idea of a totally sealed type battery--mount in any position, even upside down, no acid fumes in the enclosed trunk, and it's very compact in size. I wound up securing it with a bridge type hold down which spans the battery side to side over two threaded rods through the shelf floor w/ bonded nuts and washers underneath. I topped the rods w/ large plastic covered wing nuts. No tools are needed to remove/ install/ disconnect the battery quickly. I finished the installation by sourcing about 15' marine grade 1-0 electrical cable in red onto which I crimped AND soldered lugs. I got the wire from WEST MARINE, a national chain of marine supplies. Additionally, I put a sealed Bosch weather-pack type relay in the fuel pump circuit and located it underneath adjacent to the pump with a fused main power wire from the battery nearby. This fuse is accessible from the trunk. This attempted verbal description reminds me I need to learn to use my newly acquired digital camera, so I'll try to post some pix.

[Lanciahf]

Thanks for the detailed description! If you ever get pictures please post them.

Thanks,
Ralph