N4HHE

The submerged-or-doom theory is fantasy made up by the unknowing. If a fuel pump is moving enough fuel to keep your engine running then it is moving much more fuel than necessary to keep it healthy. If you have ever run a fuel pump out of the tank you would know it spins very fast, perhaps 10,000 RPM. Very little fuel is needed to drop that to perhaps 1,000 RPM.

Exercise for submerged doomers: What is the power consumption of the fuel pump? Convert that to heat. Now consider the specific heat of your fuel of choice. What mass flow rate is required to keep heat rise less than 10°F?

In the early days of in-tank fuel pumps most manufacturers did not think to put a safety cutoff of power to the pump if the engine was not running. In pre-digital days it wasn't easy to put a timer on the fuel pump relay, it cost money. But what happened was people would run out of gas and leave the ignition on trying to start and trying to start and burning out the fuel pump running in a dry tank. Today the fuel pump runs 15-30 seconds after the ignition is turned on. If engine doesn't start in that time the pump turns off and will not pump again until the engine starts or the ignition switch is cycled again. Thats important to know that if you can not get the engine to start before the fuel pump cuts out there is no point in continuing to crank. Must cycle the ignition key off and back on again to start the fuel pump.

bha

Careful on these trucks with the low fuel warning light and "distance to empty".

As a rule, I look for the first available diesel station as soon as the light comes on, no matter what.

I have found that if you're driving on the highway and getting good gas mileage (say after a 3 or 4hr trip), the system calculates the remaining fuel based on that MPG, and shows you a 'distance to empty'.

When you get off the highway and start looking for a gas station, you get worse fuel economy so it drops really quickly.

You may look at the distance to empty and see 60 miles, but if you get caught in stop & go traffic by taking the offramp and looking for a gas station, you might end up with 20 miles to empty!

When the light comes on, take the next exit (if on highway) or keep your eyes peeled for the next available diesel pump and fill up (if in city)

N4HHE

This is just the kind of thing that gets my goat when EV proponents claim "80 mile range is enough for 97% of all drivers!" I think that comes from the mouths of New Yorkers who have never owned their own automobile. I'm getting worried when my range is down to 80 miles. None too happy to start with a "full tank" of only 80 miles altho thats the upper limit of what my dirtbike will do.