fuel warning accuracy

[WOADKIL]

My truck has never been below 1/4 of a tank and that was when I ran some fuel system cleaner in the gas, otherwise I never let it go below 1/2 a tank. Why would you even want to push it lower?

1- Too lazy

2- Like to hear "LOW" chime every 5 miles

3- Want to pick up and clear out the dregs at the bottom of the tank

4- Passed the last chance gas station 35 miles back

5- No dinero

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[Dr. Zaius]

Since the fuel pump is cooled by being submerged in the fuel, letting it get low often can be a bad thing.

GMs used to be notorious for eating fuel pumps if you regularly ran them below 1/4 tank.

Also, ALL the zombie Apocalypse preparation books tell you to never let it get below 1/2 tank since you need to be ready just in case.

I usually fill between 1/4 to 1/2 depending on:

Lazy
Line at the pumps when I drive by
Weather I may have to stand in
Current mood
Gravitational alignment of the major planets and constellations

 

[Dgc333]

Since the fuel pump is cooled by being submerged in the fuel, letting it get low often can be a bad thing.

That's an old wives tail. If fuel is flowing through the pump it is getting all the cooling it needs. I have replaced fuel pumps in vehicles that sit close to the top of the tank and would require you to have over 1/2 a tank to keep it submerged. Of course if you run the tank down to the point you start sucking air you could have an issue.

FWIW, I have a Walbro pump feeding the fuel injection my Hot Rod. It is mounted to the frame under the car and it is the same part that would be mounted inside the tank on 400+ HP performance car.

 

[Dr. Zaius]

That's an old wives tail. If fuel is flowing through the pump it is getting all the cooling it needs. I have replaced fuel pumps in vehicles that sit close to the top of the tank and would require you to have over 1/2 a tank to keep it submerged. Of course if you run the tank down to the point you start sucking air you could have an issue.

FWIW, I have a Walbro pump feeding the fuel injection my Hot Rod. It is mounted to the frame under the car and it is the same part that would be mounted inside the tank on 400+ HP performance car.

Then all the GM pumps I replaced were just junk then?

If so, not surprised.

 

[Dgc333]

Then all the GM pumps I replaced were just junk then?

If so, not surprised.

Not sure it was a GM thing I have replaced pumps in a lot of different brands. They all have gotten better and you aren't seeing as many fuel pump failures these days.

There are two reasons the OEs put pumps in the tank.
1. These pumps are more efficient pushing fuel than sucking it. By having the pump close to the fuel they do not have to suck as much.
2. Electric pumps are noisy. By putting them in the tank the noise is absorbed by the fuel.
FYI, when I first mount the fuel pump in my hot rod it was bolted to the frame I used the rubber insulated bracket that came with the pump. The noise the pump made could be annoyingly heard above the relatively loud exhaust. I remounted the pump using 3/4" thick isolating bushings which made a significant difference but was still noticeable with the engine running. I then wrapped the pump in Dynamat which made the pump quite enough to not be heard with the engine running.

FWIW, if the OEs were really concerned about the pump being in the fuel for cooling they would not be making the pumps from plastic these days. Plastic is a thermal insulator and would be a poor choice if you were looking for the fuel in thank to cool the pump.

 

[Dr. Zaius]

It has been years since I replaced a fuel pump, but then I don't work on other people's cars anymore either.

During the late 90's through the mid 2000's it seemed like GM pumps were conking out with boring regularity. And the Airtex pumps they brought me to replace it with weren't any good either.

After several replacements and then the replacement dying all too quickly, I said No More.

Take it to a garage.

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