Fuel Pump Overheating: Fact or Fiction?

[Shel_B]

Recently, I saw an auto care video in which the guru claimed that one should not consistently run your car with less than 1/4 tank of gas. Doing so could overheat the fuel pump and cause it to fail or work poorly.

I believe that, if it does happen, it would only happen on some cars in some situations, depending on their designs.

So, Fact or Fiction?

 

[Boomer]

I've heard this for years and always felt that there might be some truth to it. I always fill up when the tank is at half empty.

 

[Warstud]

Fix the Title It says "Fuel Filter"

 

[rob1715]

I'm in agreement to fix the title. That said, I've never seen evidence that running a fuel pump dry would cause it to overheat. However, just because I don't see it doesn't mean it does not exist (Object Permeance). One could conclude that the gas does keep the fuel pump lubricated, and without that lubrication, friction would develop, then heat. And many car makes and models have the fuel filter in the gas tank, unfortunately. And many others with a greater knowledge about the subject have said the same. My vote is yes, the pump would overheat.

 

[GON]

Guess that may imply that the temperature of the fuel in the tank also impacts the longevity of the fuel pump? Fuel pumps in Seattle should last longer than fuel pumps in Houston???

 

[Wrenchturner44]

Shel, it is a FACT! Take a look at this fuel pump primer from Summit Racing.

What type of electric fuel pump should I use?

help.summitracing.com

The good news is that even though submerged "in the tank" pumps have gotten much more reliable, auto manufacturers have gotten smarter about servicing them. Many newer cars now have access holes or hatches under the back seat that allow fuel pumps to be changed without the necessity of dropping the fuel tank.

Bosch and Walbro in-line pumps have pass through cavities near the armature to help the "pass through" fuel cool the pump motor.

 

[Jimmy_Russells]

I always thought it was bogus until I had my Mk6 GTI for about three or four years (bought new) , I used to always run the tank right down to nothing about once a week, and the fuel pump died really early, at like 45-50k miles or something. So it's an anecdote but I certainly believe it more now.

 

[Imp4]

Shel, it is a FACT! Take a look at this fuel pump primer from Summit Racing.

What type of electric fuel pump should I use?

help.summitracing.com

The good news is that even though submerged "in the tank" pumps have gotten much more reliable, auto manufacturers have gotten smarter about servicing them. Many newer cars now have access holes or hatches under the back seat that allow fuel pumps to be changed without the necessity of dropping the fuel tank.

Bosch and Walbro in-line pumps have pass through cavities near the armature to help the "pass through" fuel cool the pump motor.

That's odd.

Bosch and Walbro use a design that cools via circulation, i.e. the pass through cavities. This design functions with almost zero fuel in the rank.

Simultaneously , Summit claims it is the subversive effect that designers use to prolong life.

Two very different approaches to solving the issue.

 

[kschachn]

Meh, maybe it's a problem with certain pumps and not others. In over a million miles combined I run all of my cars down to near empty every tank and even my 25 year old Accord and my 22 year-old Sienna (with over 450,000 miles at this point) have their original fuel pumps.

I also never use any sort of aftermarket fuel additive nor do I watch when the tanker truck is at the station.

 

[GSCJR]

I'm with @kschachn on this one. My cars live with the low fuel light on and never changed a pump, ever.

 

[adams355]

The high flow pumps are more susceptible to this. It is a 'thing'. If you ever want to see how hot the pump and fuel can get put a small restriction in the forward or return line.

 

[supton]

I suspect some models had a problem, and I’d bet that today most don’t.

 

[Drew7a]

I suspect pump cavitation occurs more when fuel level is extremely low and depending on driving style and conditions is what causes the failures.

 

[mightymousetech]

A pump is cooled by fuel running through the inside of it.

 

[RooflessVW]

The lower the fuel level, the hotter the fuel gets. As said above this could also result in an intermittent supply which isn't good for any pump.

Consider modern fuel injection systems operate at 20,000+ psi.

 

[mightymousetech]

The lower the fuel level, the hotter the fuel gets. As said above this could also result in an intermittent supply which isn't good for any pump.

Consider modern fuel injection systems operate at 20,000+ psi.

They only operate at that pressure from the HPFP to the injectors, which is all on the engine. Modern fuel systems are also returnless, so any fuel that leaves the LPFP in the tank will never return to the tank.

 

[Snagglefoot]

I would think fuel in a tank will eventually reach average ambient temperature. If that’s 90 F in Texas then the pump is moving 90 F fuel. That pump will be operating at that temp. If the pump is creating heat while operating it will warm the fuel. Someone should have data on that. Now bittoggers will be putting thermocouples on their tank.

 

[RooflessVW]

They only operate at that pressure from the HPFP to the injectors, which is all on the engine. Modern fuel systems are also returnless, so any fuel that leaves the LPFP in the tank will never return to the tank.

*Some*

My TDI isn't. Compression generates heat. You can watch the fuel temp climb the longer you drive it. It climbs higher the lower the fuel level gets in the tank.

Not every car on the road is brand new or the same.

 

[RooflessVW]

I would think fuel in a tank will eventually reach average ambient temperature. If that’s 90 F in Texas then the pump is moving 90 F fuel. That pump will be operating at that temp. If the pump is creating heat while operating it will warm the fuel. Someone should have data on that. Now bittoggers will be putting thermocouples on their tank.

Moat newer cars should have a fuel temp sensor already.

 

[Pelican]

Modern fuel systems are also returnless, so any fuel that leaves the LPFP in the tank will never return to the tank.

This is new to me, good to know.