Somebody explain how this is healthy for an engine

x219c · March 27, 2017

I always figured that the pump has to pump the gas through it and as that happens the heat would probably be transferred to the gas as it passed through. Of course, it can pass heat by sitting in the fuel, but I would think that would only work when the tank is pretty much full.

I wonder what the people with larger tanks would do? There's a lot more time for the tank to be less than full and over 1/4.

All of this is from someone who has never changed, seen, or otherwise interacted with a fuel pump. So, of course, I'm probably completely wrong.

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tnchevy · March 27, 2017

Just because you run your tank empty does not mean your pump is just going to up and quit on you but as others have said, it the gas keeps the motor cool. I have changed the fuel pump out of the last 3 chevys I have owned and that is with me never going below 1/4 tank. On my 2002 model I actually cut out an access hatch in the bed so I wouldn't have to remove it (or drop the tank) to get to the fuel pump.

CounterMeasure · March 27, 2017

People are concerned about the little low pressure pump in the tank staying cool via immersion, but have no worries about the high pressure pump in the engine compartment that works much harder being heat soaked from engine and radiator heat?

Does keeping that fuel pump immersed lengthen its life? In today's pump designs and plastics, it really doesn't make a difference anymore. Many I have worked with have very high continuous run temps. All will fail eventually, but unlikely due to heat. Many pump failures are attributed to heat, but actually, heat is great for *stressing* an already weak failing pump to show its true health.

The better reason to keep the tank from going below 1/4 full is fuel starvation. Since the tanks don't have baffles, starting, stopping and some cornering can cause the pump to not pick up fuel as the fuel sloshes away from it. A dry pump is hard on a pump because the fuel is also the lubricate for the pump.

Sierra706 · March 28, 2017

People are concerned about the little low pressure pump in the tank staying cool via immersion, but have no worries about the high pressure pump in the engine compartment that works much harder being heat soaked from engine and radiator heat?

Does keeping that fuel pump immersed lengthen its life? In today's pump designs and plastics, it really doesn't make a difference anymore. Many I have worked with have very high continuous run temps. All will fail eventually, but unlikely due to heat. Many pump failures are attributed to heat, but actually, heat is great for *stressing* an already weak failing pump to show its true health.

The better reason to keep the tank from going below 1/4 full is fuel starvation. Since the tanks don't have baffles, starting, stopping and some cornering can cause the pump to not pick up fuel as the fuel sloshes away from it. A dry pump is hard on a pump because the fuel is also the lubricate for the pump.

The high pressure pump in the engine compartment it run off the cam, not by an electric motor.

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TxTruckMan · April 5, 2017

A large majority of pumps in the world are not submerged inside of fuel tanks and they work just fine. Not going below 1/4 is a myth that has propagated around for many years now. I always run down to empty and have only replaced 2 fuel pumps in my entire life - one on a 1996 Silverado after 200k miles and 15 years, and one on a 2003 Yukon with 37k miles. That year was notorious for having crappy GM pumps. The replacement pump lasted another ~175k miles and 12 years until we sold it.

StillOffshore · April 5, 2017

I don't understand running until the fuel light comes on. Has anyone been standed from doing that?

sdeeter19555 · April 5, 2017

I don't understand running until the fuel light comes on. Has anyone been standed from doing that?

If I did that I wouldn't be able to count the times I would have been stranded. Get stuck for a few hours on the turnpike for an accident, get stuck between interchanges on an interstate for an accident or construction, misjudge the distances between interchanges, find out the station you were eyeballing is closed, etc.

When I travel, I never get below half a tank. When I travelled for work, I had a 60 gallon aux tank gravity feeding the belly tank, and the 38 gallon belly tank never came off full.

And for those that don't think that can happen, I burnt over 3/8 of a tank idling one day, stuck on I-70 between interchanges for an accident...it was -25F outside, so not running the truck was not a viable option. It is amazing how much fuel is burnt just idling.

I also ran into a situation where the lonely station on I-40 in Texas had no fuel...guy in the F250 next to me told me he was on fumes, I just flipped the cap back on and headed for the next interchange 25 miles down the road...I had half a tank of fuel left.

I've heard both that running low kills pumps and that it doesn't make a difference. I think it has a lot to do with quality of materials and the way they operate today.

That said, I will probably have mine changed as PM around 125k. That's the only thing that could strand you without any possible quick fix.

The last truck had known fuel pump issues (external pump), so I bought a high dollar FASS to fix that issue...then the FASS burnt up in 130k miles and I limped home on the OE pump that I left hanging on the side of the engine luckily. So even the aftermarket aren't fail proof.

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StillOffshore · April 5, 2017

That's what I'm saying...fuel pump life arguments aside....why wait until the last minute to fuel up?? Do the same people that wait for the fuel light to come on also put $5 at a time in the tank? I just don't get it. Too easy to avoid being stranded.

ChevyMan2015 · April 5, 2017

When the fuel like come on you have like 30 miles or more left. I have never run out of gas. Ever. When the fuel light comes on, I get gas. Again, sometimes this depends. If I am close to the light coming on and I know I am going to be driving a distance, then I fill up a bit early.

Edited April 5, 2017 by ChevyMan2015

TxTruckMan · April 5, 2017

I don't understand running until the fuel light comes on. Has anyone been standed from doing that?

The fuel light comes on when you have like 40-50 miles to empty - according to the computer. I drive 45 miles round trip to work each day and almost always go another day before I fill up so that I can hit a specific Chevron that I like. And then even after that the tank still only takes like 23 gallons - so there's still 3 gallons in the tank when the computer thinks you're "empty." 3 gallons is still 45+ miles for me. GM puts a lot of reserve in the Distance-to-Empty calculation.

That's what I'm saying...fuel pump life arguments aside....why wait until the last minute to fuel up?? Do the same people that wait for the fuel light to come on also put $5 at a time in the tank? I just don't get it. Too easy to avoid being stranded.

I wait until the last minute because I don't like filling up with gas every week. I have better things to do than sit at a gas station for 10-15 minutes every 4-5 days. I can usually make it almost 2 weeks between fill ups. In the city, there's a gas station every block, so there's no chance of getting stranded. On the highway I do usually fill up more frequently, but only because my wife and kids can't make it more than 3 hours before needing to stop and pee. I wouldn't let it get below 1/4 tank otherwise.

Edited April 5, 2017 by TxTruckMan

StillOffshore · April 5, 2017

I get the not wanting to take the time to fill up. I hate that as well, but what if there's a bad accident? Stuck sitting in traffic for an hr or more? I mean, it happens.

I guess I'm just envious...I'm too scared to run the truck until the light comes on.

sdeeter19555 · April 5, 2017

That's what I'm saying...fuel pump life arguments aside....why wait until the last minute to fuel up?? Do the same people that wait for the fuel light to come on also put $5 at a time in the tank? I just don't get it. Too easy to avoid being stranded.

I personally have never seen the fuel light in any of the cars or trucks I've owned in the past 20 years...I don't tempt fate or my bad luck.

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TxTruckMan · April 5, 2017

I get the not wanting to take the time to fill up. I hate that as well, but what if there's a bad accident? Stuck sitting in traffic for an hr or more? I mean, it happens.

I guess I'm just envious...I'm too scared to run the truck until the light comes on.

That's nearly impossible where I'm at. I drive through major construction every day on I-35 in North Fort Worth. Two narrow lanes for several miles with cement barriers and no shoulder. (It's better now - almost done!) There's a bad accident every couple of months where they shut the freeway down. They always re-route us if it's going to be a while, but I've never been delayed more than 30 minutes total - and that's still with the ability to divert if I need to.

And maybe it's different in extreme cold (don't have that in Texas), but your truck can idle easily idle for about an hour on a gallon of gas. At "empty" you probably have 2-3 gallons left - so 2-3 hours of "idle" time.

Don't get me wrong, it's good to be safe rather than sorry, but GM put that same philosophy in their computer warnings. I don't drive to the last drop, I just don't plan on getting gas until my truck tells me to.

Edited April 5, 2017 by TxTruckMan

sdeeter19555 · April 5, 2017

That's nearly impossible where I'm at. I drive through major construction every day on I-35 in North Fort Worth. Two narrow lanes for several miles with cement barriers and no shoulder. (It's better now - almost done!) There's a bad accident every couple of months where they shut the freeway down. They always re-route us if it's going to be a while, but I've never been delayed more than 30 minutes total - and that's still with the ability to divert if I need to.

And maybe it's different in extreme cold (don't have that in Texas), but your truck can idle easily idle for about an hour on a gallon of gas. At "empty" you probably have 2-3 gallons left - so 2-3 hours of "idle" time.

Don't get me wrong, it's good to be safe rather than sorry, but GM put that same philosophy in their computer warnings. I don't drive to the last drop, I just don't plan on getting gas until my truck tells me to.

I agree it depends on the situation...you get in some areas and it's still nearly 100 miles between stations (thinking 278 between DFW and Amarillo) or trekking across 80, 90, or 94 up north.

I've been lucky enough to be stuck for accidents and construction for hours and hours, and that was on the turnpike right near Philadelphia!

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Chev-mekanik · April 6, 2017

All of the fuel pump modules in the tanks now integrate a reservoir in them to supply fuel at a constant rate and keep them submersed in fuel when tanks are running low or in fast manoeuvres or hills.