Shop Press

Shop Press is the news and idea hub for everything related to working on cars and trucks, focusing on repair, technology, and wrenching lifestyle.

From the creative minds at:

FEATURE STORY

Hot Off the Press

P0420/P0430—The #1 DTC in the Country

DTCs (Diagnostic Trouble Codes) P0420 and P0430 are generic industry codes and part of the OBD-II standards. The descriptor labels the code(s) “Catalytic Converter Efficiency Below Threshold – Bank 1 (or 2)”. And the number one part sold to repair this problem is a...

Troubleshooting Fuel Trim–ASE Practice Questions (VIDEO)

Description Technician A and Technician B are discussing ways to use fuel trim as a troubleshooting aid. Technician A says that fuel trims that are correcting for a lean condition at high RPM and load conditions indicates a problem in fuel delivery. Technician B says...

Add or Delete These Simple Parts to Help Customers Save Money

Looking for an easy way to win over your customers that they’ll enjoy every time they drive? Look at their vehicles from a hypermiler’s perspective. In case you haven’t heard the term before, the hypermiling community is obsessed with optimizing their vehicles’ fuel...

Are You Properly Checking Hub Bearings For Wear? (VIDEO)

Description The old “grab the wheel and shake” test you may have used for tapered bearings doesn’t apply for the hub bearings found on most of today’s vehicles. Pete Meier explains how a dial indicator is necessary for a true wear check.Related Videos

Efficiency is the Name of the Game

Someone once told me that successful auto repair is a game of inches. But in our fast-paced, ever-evolving industry, inches are no longer accurate—we need to hit the bullseye every time. Margins are tighter, technology is advancing rapidly, and customer expectations...

Misfire Cause–ASE Practice Questions (VIDEO)

Description Technician A is diagnosing a misfire. He states that a misfire is caused by a fault in the ignition system and that new plugs and coils will repair the problem. Technician B says that a misfire is detected when the ECM detects a variation in crankshaft...

A History of the U.S. Presidential State Car (Part 2)

In Part 1 of this piece, I traced the history of the U.S. presidential state car from the beginning to the Kennedy Lincoln Continental. In this part, I’ll pick up with President Lyndon Baines Johnson’s state car and continue to the present day.1967 Lincoln Continental...

It’s totally fine to run your fuel tank down to empty

by | Jan 5, 2023

One of the pieces of automotive wisdom that’s been repeated by publications and mechanics alike for ages is that it’s not good to run a fuel tank below some arbitrary fill point, like a quarter of a tank. At some point, that probably wasn’t bad advice. But today? It’s hooey, for the most part. Here are a few reasons to set your mind at ease the next time you’re running around on “E.”

The pump is not going to suck up sediment

This is probably the most-oft-cited reason to not zip around with a full load of sailboat fuel. “You’ll suck up crap from the bottom of the tank and then it wipes out the pump.” It sounds good in theory, except for a few things. First, most modern fuel pumps have “the sock,” a strainer on the bottom of the pump to keep sediment out.

Second, most modern fuel dispensers have an on-board filter to remove junk before the fuel ever enters the filler pipe.

Third, and perhaps most importantly, the sediment goes to the bottom of the tank, right? “Conventional wisdom” says when the fuel level gets low, now the pump can suck up all the sediment left at the bottom of the tank. Except that the sediment and the fuel pump both sit at the bottom of the tank regardless of how much fuel is in there. The pump sits low so it can utilize as much of the fuel in the tank as possible.

Having a low fuel level changes neither the position of any sediment in the tank nor the possibility of sucking up all this mud people believe is inside fuel tanks, which brings us to the next point.

A fuel gauge is indicating a low level of fuel in a vehicle.

Yikes! Have no fear. Image by Josh Seasholtz.

Sediment isn’t even in the tank in any great quantity

There are filters on the dispensers, as discussed previously. And modern fuel tanks aren’t just bare steel—they’re usually galvannealed which inhibits rust very effectively. Modern fuel systems are also sealed, too, keeping moisture more or less out of the fuel tanks. Many (but not all) tanks are baffled, too, so if there is sediment in the tank, it often gets trapped away from the fuel pump.

The manual makes no mention of this practice

Read an owner’s manual. You’ll see recommendations for fuel octane, ethanol levels, additives, and maybe a reference to Top Tier fuels. What you won’t usually see is an owner’s manual recommending that refueling happen at any time before a certain spot on the gauge. The tank and pump were designed within a given operating envelope. Running to the bottom of the tank is inside that envelope.

You won’t burn up the pump

This is probably the second most oft-cited reason to keep the tank full. The fuel pump does indeed use the fuel it pumps to cool itself. The story goes that if the pump can’t get fuel, it heats up and eventually goes kaput.

I hear this and I am reminded of teaching my son to swim. When he would have a freak out and insist he was drowning, I would calmly point out to him he was screaming. If one is screaming, one can breathe. The fuel pump is the same: if the car is being driven on “E,” without any driveability issues, logic would dictate fuel is making its way to the injectors, and the pump must be pumping it, so we know it’s being cooled as designed.

A fuel gauge's needle is on empty, indicating a possible no-gas situation.

You paid for the whole fuel tank, why not use it? Image by Josh Seasholtz.

It’s super inconvenient

Why would you voluntarily cripple your own range and spend more time than you need to at a filling station? I’m not saying don’t fill up if fuel options are limited, but pretending a few gallons of your tank don’t exist is not some secret hack to long-lived fuel pumps, I promise.

Other types of vehicle require the full range of the tank be used

I spent (and am still spending) many years of my wrenching career fixing two-wheeled machinery. A fuel-injected motorcycle also uses a fuel pump set up just like a car, but due to the small size of the tanks, they’re run to the bottom regularly. Many common motorcycles, like the ubiquitous Harley-Davidson Sportster with its 2.2 gallon “peanut” fuel tank, can’t make even 100 miles on one tank of fuel. Running down to the very last drop is common practice. In fact, many riders (self included) will carry auxiliary fuel for when the inevitable running out of fuel situation happens.

I wasn’t replacing motorcycle fuel pumps in any great quantity. They don’t really mind being run from the top of the tank right down to the bottom.

There is one time (OK, maybe two) you might avoid running dry

If you’re storing a vehicle, a full fuel tank of treated fuel is probably best to displace moisture and keep oxidizing air at bay—rust doesn’t usually form where there is little oxygen.

I might also avoid extreme forays into the no gas zone if using the “miles to empty” feature, too, since that’s a calculated number and not real-time information. However, in the case of a modern vehicle operated regularly under normal conditions, there is next to no reason to not use the tank’s entire capacity. Remember, correlation is not the same as causation. If a fuel pump dies when the gauge is on “Empty,” other factors were likely at play.

 

The articles and other content contained on this site may contain links to third party websites. By clicking them, you consent to Dorman’s Website Use Agreement.

Related Articles

Shop Press Comment Policy

Participation in this forum is subject to Dorman’s Website Terms & Conditions. Please read our Comment Policy before commenting.

Subscribe
Notify of
guest
10 Comments
Newest
Oldest Most Voted
Inline feedback
View all comments

Get Articles In Your Inbox

Subscribe to receive a monthly email summary of our latest Shop Press stories.

Shop Press

I agree to the above privacy statement and T&Cs

Thanks! You're now subscribed.