Did the factory change the material used on the center tunnel fuel lines when they moved the fuel pumps up front?

BeeJay’s fire got me thinking about this a bit. On the stock FI set up, does the fuel flow back to the tank in the return line at the same high pressure that is uses to feed the injectors? If not, by moving the pump to the nose of the car, does that change the feed line in the center tunnel from low pressure to high pressure, adding additional stresses to both the line and the simple hose clamps that hold everything together down stream?

When I recently pulled my still rear mounted fuel pump to do my -6 conversion, the remaining gas in the tank drained very quickly/easily just through gravity. I understand that most pumps today are pushers, not pullers, and as well that the pump will be much cooler up in the nose of the car. But being that gravity does most of the work (at least in my car), wouldn’t it be safer to keep that high pressure out of the cabin and keep the pump mounted in the stock early location?

My other big concern is what seems to be common on the bird board with the 911 guys. There are so many threads where guys say to just keep the FI pump and use a regulator to drop the pressure in to the 3.5 – 4 needed for a Weber conversion. Why would you want all of that pressure built up on the one side of the system?

I agree with this and did the new low pressure (3-4 PSI) fuel pump with my Weber conversion. No regulator to fail at the most inconvenient time.
Why have all that fuel pressure in the lines when you don't need it!

If you use fuel injection with high pressure fuel with the pump up front, you should really replace the stock lines that go into the car inside the tunnel. The stainless lines that are available aren't that expensive and considering what could happen with the 40 year old plastic lines, darn right cheap. If you switch from FI to carbs, change the fuel pump from high pressure to a 3.5 psi pump. I have Weber carbs with a CB performance rotary pump at 3.5 psi with the pump in the engine compartment and it has worked great for 8 years. I used truck brake lines for the fuel lines. There's something about high pressure fuel running inside the car through plastic fuel lines that I just don't trust.
Cheers, Elliot

It is my understanding that they did change the feed line when they moved the pump up front.

Jim

That's true. They went to the black Teclamit nylon reinforced line that is the standard for CIS. CIS runs at 5-6+ bar, D- and L- jet run at 2. It's also 8mm in both directions, not 8 and 9.

The Cap'n

I didn't know that. So my '76 has this Teclamit nylon stuff? I knew it was black, and 8mm in both directions.... son of a gun.

Regardless of material, it makes sense to invest the $50 in a new low pressure fuel pump so you don't have the issues. Probably would be best to incorporate a fuel return line as well, but not necessary.

Going to the stainless lines would certainly be a good idea as well. You have seen what can happen in the blink of an eye!

The supply line is pushing into a regulator to build and maintain pressure. The return line flows from the regulator to an open tank. So, no the fuel pressure in the return line is much less than the supply because it flows unrestricted.

I don't understand to why run a regulator? That's just more hardware, an extra fuel line, and more fuel pressure that can cause problems if something happens.

A regulator costs money, a 3.5 fuel pump is a few bucks more, sell the old FI fuel pump (I sold mine for $80, 3.5 fuel pump is $60) - come out ahead!

A regulator tyically will help prevent vapor lock. This works by flushing cooler fuel through the lines. On a carb car it is not needed if you have a low pressure pump. I do no recommend using a FI pump and regulate it to low pressure.

No, they used Nylon 11 (Clear/White on rear mounted pumps, Black on front mounted pumps) on all the cars. They did put a beaded piece of tubing inside the hose end on the front mounted pump cars so the hose clamp could be tightened properly.