Limiting FI performance w/older gas tank?

[steviebsf]

hello spider enthusiasts & forum contributors,

I dropped an 82 FI engine/trans/drivetrain in a 78 (btw i had a much easier time dropping the engine/trans in almost horizontal (with the rear of the car a little higher), than the vertical suggestion and didn't have to remove any steering parts, but thats another post).

My question is: Am I really limiting my FI fuel draw using the original 78 (carbureted) gas tank? Anyone with first hand experience on switching tanks and noticing improvement. I have larger fuel lines before the fuel pump to make a little more fuel available, in theory. If the fuel path was a straight shot to the FI rail, it would be a no brainer. What I can't figure, is if the fuel filter, fuel line curves and transitions from rubber line to steel line and back to rubber have enough natural resistance, so that any pre pump limitations become irrelevant? Your experiences are greatly appreciated.

Much respect & props to forum contributors & so cal mark for your indispensable info & advice.

[So Cal Mark]

the fi tanks use 1/2" hose from the tank to the pump, so it's feasible to starve the pump under high demand situations using the 7mm hose. You're also drawing the fuel from a higher location on the tank and those electric pumps don't create much suction. I'd try driving the car under high load up hill, if it doesn't feel like it's running out of fuel you're probably okay. You can always install a helper low pressure pump between the tank and pump to keep the fi pump full of fuel. Many cars and trucks used in-tank helper pumps in the 80s before high pressure in-tank pumps became the standard

[steviebsf]

Hey thanks Mark,

I too have 1/2 " line from tank to pump. The pre pump pump is an interesting idea...

Honestly, I like to really push my acceleration all the time and have never noticed what i would call "starvation". That said, I imagine it is hard to distinguish possible slight fuel limitations from the normal factors that limit acceleration (gravity, air flow, etc). I wish the acceleration of the car was directly proportional to the depression of the pedal, but then doesn't everyone : )

[divace73]

There is the option of using a swirl tank to solve any issues