Duel tanks and efi

[4EyedTurd]

If an 88 model truck had an external fuel pump only would using one of those fuel pumps work on a duel tank setup inbetween the fuel selector valve and the motor?

 

[RonD]

'88 Ranger would also have a "lift pump" in the fuel tank, and then the external high pressure pump in the frame rail.

Yes, you could add second tank, with lift pump, and both could use the one high pressure pump.

The lift pump is a 9psi pump used for carb engines, the high pressure pump(40psi) was added for EFI for a few years, until high pressure pumps were moved inside the tanks.

You will have Return fuel lines as well, so tank selector needs 6 ports, 2 for each tank and 2 for the engine.

One reason you don't see many Dual Tanks any more is the emissions requirement for fuel tanks, the EVAP systems need to be added to the cost of the second tank which makes it a more expensive and complicated option from the factory.

EDIT:
May have assumed too much.
If it is not a Ranger and there is only an external pump then yes, both tanks can share the one pump, this worked fine for many many years when mechanical fuel pumps, located on the engine, were used.
One heads up on the external pumps, don't run tanks dry, they can be hard to prime

 

[4EyedTurd]

Dammit, I forgot about return lines. My truck is dual tank carb'd and I'd like to put efi on but trying to have both tanks functional seems like its gonna be a pain in the ass.

 

[tomw]

Run ONE return line, and have it return to a tank you choose. If that tank gets full of 'returned' fuel, switch to it, and use some up. Switch back when you have emptied some out... The fuel doesn't care where it goes. And it will be a bit 'heated' by traveling up to the engine, so will have a chance to cool down sitting in the other tank, waiting for its next run...
I think it would work, and I suppose you could rig an 'overflow' or 'full' line to let fuel travel from the 'returned' tank to the other tank if it indeed got full of 'returned' fuel.
I think I'd be checking boneyards for a dual tank setup that was EFI already, and getting two sets of 'in tank' equipment. Modifying fuel lines to hook it all up might not be too bad.
tom

 

[RonD]

In the late 90's Ford switched to Returnless EFI, running 65psi.

EFI requires more than just fuel injectors and a fuel pump, to gain any benefit from it you need to control it.

Carbs have jets, air flowing passed the jets sucks out fuel, the more air passing by the more fuel is sucked out, so pretty simple system, but not very accurate and requires constant tuning for best economy and performance.

For fuel injection there are no jets so no "air flow control" for fuel, for best results you need an EFI computer/processor and sensors.
MAF sensor is best air flow detector, MAP sensor also works but MAF is better.
Electronic distributor sensor or distributorless Crank position sensor is needed to time injectors for #1 TDC
TPS(throttle position sensor) is needed for quick throttle response; air flow increase when throttle opens has a delay you can notice, this is why carbs had "accelerator pumps", they squirted extra fuel into engine when throttle was opened quickly to avoid this delay.
TPS does the same thing for EFI.

Since there are no idle jets, using a manual idle screw can be a problem, most EFI uses IAC Valve that is controlled by EFI computer so it can hold a stable idle and maintain idle level air/fuel mix at the same time.

Then there is the Choke, a cold engine needs extra fuel to stay running, also a higher idle.
Choke Plate worked by restricting air flow into engine, this increased the vacuum level and sucked more fuel from the jets.
Can't use a Choke Plate with EFI, no jets to suck extra fuel out of, so computer needs some way to tell if engine is cold or warm, ECT(engine coolant temp) sensor is what is used.
When engine is cold computer adds extra fuel and kicks idle RPMs higher using IAC Valve.

O2 sensor helps computer keep a stable air:fuel mix while driving, one of the big benefits of fuel injection is this feedback allowing for better fuel economy on the fly.


What engine are you thinking of converting to EFI?

 

[tomw]

The most simple and quick method to convert the 84 to EFI, with dual tank setup, would be to find one in a boneyard, and strip all components for installation in the 84.
The 85 California 2.3 had EFI that could be made to work, I think.
If I were trying this, I'd buy the donor truck and park it alongside the victim, and start swapping parts.
I would also invest in the Ford EVT Manual. Electrical, Vacuum and Trouble shooting. It has the schematics for just about everything and diagrams of connectors, and vacuum information. It would be a very useful tool for someone wanting to swap in an EFI system.
tom