Fuel injection for #2548

Very nice.  Thanks for posting.  Please keep us up to date.

Which sending unit is this based on?

Sending unit?  This assembly goes in the opening originally used for the fuel pick up; the center one in the tank.  The sending unit for fuel level is stock and is not changed.  When I get time to post more, it will be more clear.

It appears you are mounting your new fuel pick-up assy. in a non-stock opening in the top of your fuel tank. A better photo of the top of your tank would clarify.

I see where the confusion comes from.  The fuel pump assembly is propped up next to the tank to be posed for the photo.  It appears to be near the level sender opening, and at the same angle, but that is just a coincidence.  It actually mounts in place of the original pick up assembly in the middle opening.

Here is the business end of the unit, along with a photo of the entire assembly.  The flange is 1/4" thick aluminum.  The carb pick up / FI return line is 3/8" aluminum tube.  It also serves as the main mechanical support for the pump itself.  The FI pump output line is 5/16 aluminum tube, the same as the output nipple on the pump itself.  

These two tubes are brazed / soldered to the flange with that zinc brazing technique.  It is genuinely useful for some applications, but harder to do than the advertisements make it seem.

You can see that both tubes are bent slightly about 4" below the flange; this compensates for the angle of the mounting surface, and makes them vertical inside the tank.

The 3/8" tube is also flattened slightly where the pump is attached to it.  This gives a better support surface for the pump body so it doesn't move around.  It also reduces the overall diameter of the assembly there, as it just barely fits in the stock opening of the tank.  The pump is held in place with safety wire for the same reason, as there is not enough room for hose clamps.  The very end of the 3/8" tube is bent out slightly, so it doesn't interfere with the pick up filter of the pump.

The two aluminum tubes had to be brazed to the flange first due to the heat involved.  I had to shorten the nipple of the vent piece about 1/4" so it could be screwed in.

As I said in my earlier posting, I do not believe the hole you’re using for this assembly is stock. The only large hole should be the one used by the sending unit (and fuel pickup on most Pantera’s). There is another hole at the high point of the tank, for the vent and there’s a fitting that’s connected to a pickup tube, that was used on early cars but blocked off on later cars. There’s also the hole for the filler neck. I believe the 3 bolt flange hole you’re using to mount your pick-up assy. has been added at some point in the car’s life.

I cannot say for sure what may have been changed before I bought the car in 1996.   My car is an early (January 72) pre-L model.  I have heard that the tank may have been replaced, as fuel leaks may have been what prompted the original owner to sell it.  I am the 4th owner.

Here is a pic of what it looked like when I took it out for refurbishment.  The sender unit to the left has no provision for fuel pick up.  The filler neck / cap to the right is original as far as I can tell.  The center piece is the fuel pick up & vent assembly.  It was held in place by 3 rivets.  After removal, I found locating notches under the flange, and a reinforcement ring spot welded to the inside of the tank.  This is somewhat visible in my first photo, and is almost certainly factory.  The only thing I changed was to install Riv-nuts in the rivet holes, so the new assembly is held in by screws.

I agree with BW on the size of the fuel lines. Unless you are running flat out at Lemans for 24 hours, the stock line sizes are adequate.

You can compensate if need be by using more fuel pressure but be cautious there since Webers run at only 3psi and Holley's at 5psi.

You only really need very high pressure for the 8 stack EFI. That pump will get set normally at 43psi (that's what the software calls for) but can be dialed up to 100 but I don't know why you would if you have the right size injectors.

On my car with 8 stack EFI the linear Bosch electric fuel pump pulls from the drain hole at the bottom of the tank and returns fuel to the stock pickup tube that has a 6AN fitting adapted to it..  There is a coarse filter before the pump and a fine filter after it.  The fuel pressure regulator is set at 43.5 PSI and matches my Bosch injectors.

The reason EFI users draw fuel from the bottom of the tank is, there's no suitable place on top of the tank, unless you're willing to modify your tank. The one possible alternative is to draw from the OEM pickup tube and return through a fitting in the filler neck. Ufo-low's tank has either been modified or it's a very unique one-off factory tank. Either way, drawing from the top is always more desirable than the drain plug option, from a safety perspective. 

I thought I read that the linear fuel pumps require that fuel is drawn from an outlet at bottom of the tank.  The linear pumps do not the umph to pull fuel up and out of the tank.  Am I correct?

That is the advice but so far I don't see an issue with my EFI 8 stack. I mounted it low. Even with the bottom of the tank.

I am using a current service fuel  pickup/float sender for supply and the original supply, as the return. It works well so far.

I had tried using the tank drain as the supply port but was uncomfortable with how low it seemed even with a banjo and fluid bolt which in that thread combination really needs to be searched for. Plus because of the contour of the bottom of the tank, it really needs a very long banjo which I could not find in that size.

@stevebuchanan posted:

I thought I read that the linear fuel pumps require that fuel is drawn from an outlet at bottom of the tank.  The linear pumps do not the umph to pull fuel up and out of the tank.  Am I correct?

Steve, I have not heard that but I suppose it would depend on the pump. The Pantera is a different application than most as the tank is so deep. The last fuel pump I used was the tried-and-true Bosch "044" pump and I'm sure it would have had the power to pump fuel out of the top of the Pantera's tank.

I took fuel from the bottom of the tank using a BAT/Setrab high-volume banjo fitting. I also mounted a 1/4" thick skid plate below it, for protection from road debris, etc.