kornellred

Is there any truth at all to the notion that it is better to refuel before the fuel level in the tank is at 1/4? Or is it simply a harmless supposition?
The primary "reason" that I have heard is that the gasoline acts as a heat sink, allowing the fuel pump to run cooler. When the fuel level is low, very little of the pump body is submerged and heat builds up , contributing to wear and tear on the seals.
It sounds pretty reasonable to me, but it could be that the heat build-up is not significant enough to be of any concern at all, as far as fuel pump integrity is concerned.
I fill up my tank at 1/4 whenever I can, out of habit. I think I developed the habit because I tend to believe it is beneficial to the fuel pump.

I won't make an appointment with a psychoanalyst for this particular compulsion!

87silver

This is one of my sayings, "In theory, practice and theory are the same; In practice, they're not".

I say this because while this theory makes perfect sense, I must draw from my experience with family members (wife, son and daughter) driving my vehicles with low fuel down to the indicator light coming on, then refilling.

In practice:
1) I had a 1993 Blazer that ended up with 140k miles / 16 years before needing a new fuel pump. Maybe I could have gotten 200k / 20 years out of it if they kept the tank at over 1/4; I don't know. I traded it in for cash for clunkers soon after I replaced the pump.

2) My wife's 2000 Olds Bravada currently has 107k miles on it, it's 11 old and still on the original pump. The fuel sending unit went, but the pump is still healthy. I'll probably change it this summer simply as a precautionary maintenance item.

3) My 2002 Chevy S10 4x4 has 71k with the original pump.

Not saying that I would get longer life out of an in-tank pump if my family learned to keep the tank at higher levels, but I would say that I'm not doing too bad. It also says that these pumps are more robust than many might think.

On the other hand, I am the primary driver of my HHR and rarely let the tank go down below 1/4. This only happens on very long trips on the interstate. I keep the tank at higher levels just out of some paranoia that I have direct control over.

bk94si

The theory does make sense but depending on how long you keep your cars, you will have to replace it once in the car's lifetime anyway. At least I do since I drive mine until up in the 200k range. I replace my Suburban fuel pump at about 100k and 12 years. I usually didn't let the fuel get too low but I bought it with 65k on it and I don't know what the previous owner did.

IgottaWoody

170k on my truck before pump change( and only figured it out because while breaking in a new cam the headers were glowing red, was down to 5 PSI but ran good)...never let it get below 1/4..but then again at 1/4 there was only 4 gal left, checked using gas pump on fill up.

BlackknighT

Also it is easier on the pump with a "fuller" tank with the heavier weight of more fuel flowing than to have the pump strain having to "vaccuum" up fuel to send to the motor.

hyperv6

The low fuel and damaged pump thing has been around for a good while. I would agree the fuel does help cool it and feel that this is true. But on the other hand I see tons of people who run a car down to the last drop and few ever have failed pumps.

For the most I drive a half a tank or less a week and I just fill up once a week. My though is never get caught will too little fuel.

Just remember 9/11 when eveyone ran on the pumps out of fear. Many had a hard time getting home because they were so low. Also look in Japan today. Many are out of fuel and little hope of getting any. So I feel it is best to fill early as you never know when you may need it.

Just last winter in Cleveland they had a major snow and some people took 8 hours to get out of down town. Many ran out of gas just sitting in traffic. That made a bad thing even worse.

But back to the pump. I feel it will help it but it will not kill it either. If the pumps today needed the fuel to cool the MFG would never let the level drop that low. They would keep a little fuel in the tank to protect it if it really needed it too cool.

Pumps today are pretty good and this cooling thing goes back to the 80's when electric in tank pumps were new and not as good.

I see more bad sending units than anything else. we had 3 1997 GM car in the family and all three had bad sending units by the time we sold them.

I see the pump cooling thing as like many other internet things. It was once true or based on a truth but today no longer applies. The smidgen of truth keeps it alive enough to fool many today.

nacademus

My 95 Riviera went 140,000 before the pump died out. My 1990 Olds Silhouette went 169,000 and still had original unit when sold. My 87 Fiero has 163,000 on the original unit. Sold. Still working.

We can average my experiences here and get 157,333 miles. However. I never let my tank get below 1/4. I think a good expectation would be about 120,000 miles out of your pump. If it hasn't failed by then, might as well replace it as PM.

All too often, parts FAIL on people and they act all caught off guard. This is why we have maintenance schedules. Things are not expected to last forever. Its best to do the replacement BEFORE you're out somewhere and caught off guard.