Can I add an external fuel pump?

So the TBI pump is only good to 12 psi. Can it be used as a feed pump for an external pump to feed the TPI unit? I'm concerned about pulling the tank down and snapping bolts and such.

I would imagine so.  There's a ton of Euro cars that use a small in tank pump to feed a high pressure external pump.  The pumps they use are smaller than a tbi pump.

It depends, you need to pick the 2nd pump so that it doesn't suck fuel through the TPI pump. If you know the flow rate at 12psi you can check.

You can use a small cell to create a surge tank.  The lower pressure pump feeds into a 1 or 2 gallon cell, usually very vertical in construction, that holds the high pressure pump.  That keeps the high pressure pump always in fuel, regardless of the level in the main tank.

In reply to Paul_VR6 (Forum Supporter) :

It'll work even then.  The current draw of the in tank pump will drop when this happens.

Pete. (l33t FS) said:

In reply to Paul_VR6 (Forum Supporter) :

It'll work even then.  The current draw of the in tank pump will drop when this happens.

I will counter "it depends." We can use a Walbro 255lph with a stock vw lift pump but an 044 will outflow it and eventually burn up, same with most bigger pumps without a surge tank. Likely will be OK but putting a hair of thought into it wouldn't be a bad idea.

In reply to Paul_VR6 (Forum Supporter) :

Good point there.  I'm assuming a generic EFI pump and not some 600hp mammajamma.  When I read "TPI" I was thinking 300hp or less.  Even a generic 190lph pump should be fine for a TPI engine.

is it really bad enough to not want to just drop the tank or lift the bed and toss a camaro/corvette/walbro in the tank? it literally hangs right in there where the TBI pump is, they're dimensionally identical. adding other pumps/wiring/relays/connections/surge tanks just sounds like exponentially more work and fail/leak points vs just dropping the pump in.

Pete. (l33t FS) said:

In reply to Paul_VR6 (Forum Supporter) :

Good point there.  I'm assuming a generic EFI pump and not some 600hp mammajamma.  When I read "TPI" I was thinking 300hp or less.  Even a generic 190lph pump should be fine for a TPI engine.

I read TPI as more as a generic EFI term, all of it depends on what the motor setup looks like obviously.

Patrick said:

is it really bad enough to not want to just drop the tank or lift the bed and toss a camaro/corvette/walbro in the tank? it literally hangs right in there where the TBI pump is, they're dimensionally identical. adding other pumps/wiring/relays/connections/surge tanks just sounds like exponentially more work and fail/leak points vs just dropping the pump in.

True enough, but have you looked under an Astro van lately that has rust to deal with?

In reply to vwcorvette (Forum Supporter) :

If it's rusty enough that you are worried about dropping the tank, the fuel lines are extremely rusty anyway and you won't be able to splice anything in them.

IME

Cutting an access hole in the floor prevents any issues with trying to drop the tank, and in an astro van that could easily have a panel made to cover the hole then carpet laid over that, seems like the easy button