[KenMaro]

Another theory/paranoia of mine which may or may not be true:

I try not to go below a quarter tank of gas. My thinking on this one was that the fuel pump would have to work harder with less and less gas in the tank, so keeping a topped off tank would be easier for my fuel pump over the lifetime of the product. I tend to keep my vehicles for 10+ years so the longer I can keep it on the road with less visits to a mechanic the better.

Am I over thinking this one or is there any truth to it?

(Sorry it's been a couple of slow days at work and these are some of the questions we toss around and debate)

[arpad_m]

The one good reason I know of not to let the tank go empty is that the pump is cooled by the fuel it's immersed in, but even then the gauge is calibrated to display E when you still have a bit of gas left, so unless you literally run out of gas, the pump should be good. I don't see why the pump would work harder when the fuel level is low, were you thinking about the slight in-tank pressure difference due the fuel departing?

In addition, we have a saddle style fuel tank with an auxiliary pump transfering gas from one side to the other, and the car first consumes the "source" side of the transfer pump completely, only then does it begin consuming from the other side where the low pressure pump is.

Thus when your gauge displays 1/2, you actually have nothing on one side while the other side of the tank is still full. When you're showing at 1/4, it means one side is empty and the other is at 1/2, which means it's even more difficult to burn out the low side pump.

In summary, just don't drive until completely empty and the car stalls out.

[ctrlz]

Originally Posted by arpad_m

In addition, we have a saddle style fuel tank with an auxiliary pump transferring gas from one side to the other...

Agree that cooling may be the only reason not to completely drain the tank, and a minor advantage i would think.

we only have one pump on the right side of the saddle (same side as fill tube). The left side contains a level sensor and pickup assembly. Right side also has level sensor. Pump drains left side first, then right. The fuel system is non-return. All the external connections are on right side. The pickup tube for left side and a vent tube run INSIDE the tank. if you ever drop the tank and get a slug of fuel in the vent tube it will be impossible to fill the tank completely. The clog will cause the gas pump nozzle to register backpressure.

[KenMaro]

Wow, right on. Thanks! That is way more than I figured went into it.

Thanks again!

[arpad_m]

Originally Posted by ctrlz

Agree that cooling may be the only reason not to completely drain the tank, and a minor advantage i would think.

we only have one pump on the right side of the saddle (same side as fill tube). The left side contains a level sensor and pickup assembly. Right side also has level sensor. Pump drains left side first, then right. The fuel system is non-return. All the external connections are on right side. The pickup tube for left side and a vent tube run INSIDE the tank. if you ever drop the tank and get a slug of fuel in the vent tube it will be impossible to fill the tank completely. The clog will cause the gas pump nozzle to register backpressure.

Hmm, thanks for the info, I must have remembered a modded car build then, I would've sworn there was a transfer pump in there (but I never had to go into the tank on mine). Anyway, I stand corrected on that one, thanks ctrlz.