20 Gallons

[jeremyc74]

I'll admit it sounds absolutely DUMB but you do see it come up a LOT and just random forum people either...

Running on empty: Low gas in the tank can be costly

"The gasoline acts like a coolant for the electric fuel-pump motor, so when you run very low, this allows the pump to suck in air, which creates heat and can cause the fuel pump to wear prematurely and potentially fail." - ConsumerReports.org

You see it from a lot of random sources, because people have been hearing it for years. It goes back to the early systems where this actually was a problem.

You won't find one single automotive company that states that anywhere in their documentation.

Automotive engineers learn from their mistakes quickly (with some exceptions for sure). There's no way a fuel system that couldn't use it's full capacity would pass testing for vehicles that were built since emissions standards were introduced. Things tightened up a lot at that point, and the push for quality control by companies like Toyota are why cars are as good as they are now.

The warranty costs alone would preclude this. With cars having warranties of 50-100k miles now (opposed to 12k miles back then) there's no way they would risk the warranty claims from pumps failing due to low fuel levels.

Honda targets a defect rate of 1 in 5,000,000 from their supplies for parts like this. Other manufacturers are similar. Allowing a failure to happen just because someone used the car in a common way would be COMPLETELY unacceptable.

 

[jhfleet]

I'll admit it sounds absolutely DUMB but you do see it come up a LOT and just random forum people either...

Running on empty: Low gas in the tank can be costly

"The gasoline acts like a coolant for the electric fuel-pump motor, so when you run very low, this allows the pump to suck in air, which creates heat and can cause the fuel pump to wear prematurely and potentially fail." - ConsumerReports.org

Many years ago I bought a new Dodge Dart based partially on the recommendations of Consumer Reports. Worst piece of crap I ever owned and I haven't trusted them since. I'm pretty well convinced that their automotive advice is worth about as much as calling a random person in the phone book.

 

[JeepKiller]

Many years ago I bought a new Dodge Dart based partially on the recommendations of Consumer Reports. Worst piece of crap I ever owned and I haven't trusted them since. I'm pretty well convinced that their automotive advice is worth about as much as calling a random person in the phone book.

Disposable dodge, every dodge anyone I've ever known has owned has been a pain.

 

[Brveagle]

You can run the motors dry forever with no liquid around them and they're fine. We did so on a regular basis on the test stands.

The only way you're going to damage the pump is by running it with the impeller completely dry for an extended period...

Well which is it? Your two statements contradict each other.

 

[jeremyc74]

Well which is it? Your two statements contradict each other.

No they don't. The motor doesn't need the liquid for cooling.

The statement "never go below 1/4 tank" or "never run completely out" is always based on people saying the pump motor is going to overheat, and it won't.

You CAN damage a pump by running it for extended periods with no liquid in the pump itself, but that can't happen on a car because (as I already stated in the other post, that you edited out) as soon as that happens the engine dies and the pump stops. The only way you can do this in the real world is to run the tank completely empty and then jump the fuel pump relay to get the pump to run. If you do that you get what you deserve.

So there's ZERO danger to your fuel pump by running the tank to near empty.

If running a car low on fuel regularly would damage the fuel pump you'd see beaters on the side of the road with failed pumps EVERYWHERE. You don't because it won't. It's another internet story with absolutely no basis in reality, at least when it comes to anything built in the last 30 years that has an in-tank pump.

As I said earlier, if it were possible to damage the pump like this there would be a low fuel shut off to prevent it, because otherwise the warranty costs would be outrageous. The whole notion is just absurd to anyone who works in the automotive manufacturing industry.

 

[NoVAphotog]

If running a car low on fuel regularly would damage the fuel pump you'd see beaters on the side of the road with failed pumps EVERYWHERE. You don't because it won't. It's another internet story with absolutely no basis in reality, at least when it comes to anything built in the last 30 years that has an in-tank pump.

Before I started reading forums I ran my previous cars down to fumes all the time and never had any issues...good ole' forum groupthink led me to believe it was this horrible NIGHTMARE thing...going back to the bmw related comment, I guess E46 fuel pumps fail because they are old and over 100k not because you run them down low!

 

[4RunnerChaos]

My truck is one that's affected by the screwed up tank sending unit, so even if it says it's bone dry I only put about 15 gallons in it. That sucks on road trips, but knowing that I have 3 gallons in reserve I'm going to start waiting until it's hit the E for a while before I stop. Not being able to get at least 300 miles on a tank on the highway is a PITA.

At least its better than my car. 13 gallons of E85 means fillups every 175 miles. :brick:

Drove 430 miles on 1-3/4 tank today. So shush about your not hitting 300 a tank!
Just kidding its really been bothering me how poor mileage I'm getting though, I don't think one of my cylinders is firing properly or burning all the fuel.
And it probay didn't help I drove in 4 wheel drive (rear drive shaft removed) at 80 mph the whole time.

 

[jeremyc74]

Before I started reading forums I ran my previous cars down to fumes all the time and never had any issues...good ole' forum groupthink led me to believe it was this horrible NIGHTMARE thing...going back to the bmw related comment, I guess E46 fuel pumps fail because they are old and over 100k not because you run them down low!

I'm of the opinion the Germans just suck when it comes to electric motors in general. On the N54 engines the electric water pumps fail at 100k so reliably it's almost like they were designed that way, and right now the blower motor is going out on mine at 120k. I'm sure that will involve tearing the whole dash out. The water pump is a $500 repair if you DIY and more like $900 at the dealer! :rant:

 

[Oprah]

Well I don't think I'm worried about damaging the pump.