Terry,
Unless you somehow vent the tank, you will either starve the car for fuel or
collapse the tank. That is a closed vented tank that vents through the carbon
canister to relieve the vacuum buildup from the fuel being pumped from the
tank. Capping the vent line without installing a vented fuel cap or otherwise
installing some other means of venting the tank.
That said, I am inclined to think that the pump you are looking at is really
referring to the more modern system of returning excess fuel and vapors back to
the tank through a third port on the pump itself. If it can't pump any more
fuel into the carbs, rather than pressurizing the line, it relieves the pressure
through the third port which is connected to the return line.
I had a 1981 S10 Pickup that had a 2.8 V6 engine. The fuel pump decided to give
up and I couldn't get a replacement so I added an electric fuel pump. The truck
had a return line but the pump did not have a port for it. I put it on anyway
and had to be very careful when I filed up because when I over filled the tank
it would run out the return line that was located at the engine compartment
where the stock pump mounted.
Regards,
Joe Curry
"Terry L. Thompson" wrote:
>
> I've managed to purchase an electric fuel pump that is not supposed to be
> used with tanks that have "vapor return lines". According to the
> installation instructions, the pump will not operate properly on these tanks.
>
> My '76 has a vapor line but it feeds directly to my carbon cannister, is
> this what they mean by a vapor return line? And if so, what problems will I
> cause by "capping" the outlet that this vapor line runs off of?
>
> I'd like to get rid of my carbon canister anyhow, so I'd like to know what
> can of worms I'd be opening if I try to cap that vapor return line.
>
> -Terry L. Thompson
> '76 Spit 1500
> Maryland
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