Keeping tank full vs refueling on E

[waterinthefuel]

My father and I get into scuffles about this all the time. He always wants me to keep my truck's tank full (say, no lower than half a tank) because when it gets low he says it sucks crud off the bottom of the tank. I tell him it's not like a toilet, there isn't a float on the top, it sucks from the bottom no matter what. Who's right?<br /><br />I don't mean leaving it empty (due to water condensation), I just mean refilling it every two weeks vs every week (in my case).<br /><br />I'm a pilot and I know that if you don't (or in the case of a car, can't) sump the tanks every flight its going to suck the gunk out the bottom whether or not you fly with full tanks.

 

[Bondo]

Re: Keeping tank full vs refueling on E

Your Dad is Right,............ Again........ <br /><br />It's the Sloshing of the fuel that picks up the Crud,+ causes it to be suspended In the fuel,......<br />Where a Full tank, when it Sloshes,.. The top surface Doesn't sweep the Bottom of the tank,.. Picking up the Crud........<br /><br />That doesn't Read like I Thought it,..... But it Is True........

 

[Bob_VT]

Re: Keeping tank full vs refueling on E

Keeping it full will cut back on the crud for two reasons -<br /><br />- first there will be more fuel to dilute the crud causing a lower crud to fuel ratio<br /><br />- condensation creates rust and collects dust particles so keeping it full will cut back on corrosion (rust in the older metal tanks and significant condensation in plastic ones)<br /><br />If these are concerns keep the fuel filters changed.

 

[JB]

Re: Keeping tank full vs refueling on E

Yup. What Dad said, plus:<br /><br />You have a few hundred miles of fuel if an emergency arises and there is no fuel to buy.

 

[rwise]

Re: Keeping tank full vs refueling on E

besides what Dad says, most newer vehicles have fuel pumps in the tank and need fuel around them for cooling purposes. No it wont go up in flames if it overheats, but it could die. Besides they can be hard to change and costly to boot!

 

[Ron G]

Re: Keeping tank full vs refueling on E

on the same lines here,why does it seem like you get better milage with a full tank then an almost empty tank??

 

[ndemge]

Re: Keeping tank full vs refueling on E

Full tank good for keeping fuel pump clean...<br /><br />But where are you getting all this sludge in your tank? I had to remove the tank from my '84 Ford this year to put in a new sender, it was PERFECT Clean inside!, I thought I would want to clean it out while I had it out, but there was nothing in there to clean.<br /><br />You open the lid to put in gas then you close it back up, where does it get dirt?

 

[KRS]

Re: Keeping tank full vs refueling on E

What rwise wrote... you need it to cool the pump.

 

[18rabbit]

Re: Keeping tank full vs refueling on E

Doesn't matter. Keep your fuel filter clean and get on with life.<br /><br />Personally, I keep the tank no less than 1/4 to 1/2 for Boy Scout reasons...being prepared, that kind of thing, nothing to do with gunk sucking.

 

[gonefishie]

Re: Keeping tank full vs refueling on E

why don't they put a magnet on the bottom of fuel tank to hold onto the loose rust and stuff like on a tranmission oil pan?

 

[BoatBuoy]

Re: Keeping tank full vs refueling on E

Around town I keep mine between E and 1/2. 1) I don't want to be stuck with expensive gas when the price goes down , and 2) I don't want to pull around the extra weight. It takes gas. Never a problem w/crud in the tank.

 

[kenimpzoom]

Re: Keeping tank full vs refueling on E

In the old days, when the tank was vented to atmospere, keeping the tank full cut down on the rate of fuel evaporation.<br /><br />Dont know if that is still a problem in todays closed systems.<br /><br />The key is to never run out of gas, as that is where the fuel pump can be hurt. Running it dry is bad.<br /><br />Ken

 

[LubeDude]

Re: Keeping tank full vs refueling on E

My opinion is that its an old wives tale! There is a small filter sock on the pickup tube anyway There shouldnt be anything in your tank to slosh around. Only reason would be to be prepared, IMHO!

 

[JB]

Re: Keeping tank full vs refueling on E

Guess I am paranoid about that, too.<br /><br />In October of 1957 I traded for a reliable car because new baby was due any day and I wanted to get her Mom to the hospital quickly and reliably.<br /><br />We liked the car so much we took a drive around the island (Oahu). Ran out of gas with the guage registering 1/4 tank. <br /><br />Long story, but Alice was born on a gurney that afternoon while I parked the car.<br /><br />I break into a sweat if the guage gets below 1/4 tank and a panic if it gets below 1/8 tank for nearly 50 years now.

 

[ZmOz]

Re: Keeping tank full vs refueling on E

Originally posted by JB:<br />You have a few hundred miles of fuel if an emergency arises and there is no fuel to buy.

Exactly. You're going to buy it and use it anyway, so why not just fill the tank while you're there? I go fill up once I get down to about 3/4 - 1/2. It reduces the already small risk of "sucking crud", it makes life easier for my old fuel pump, and I've always got enough gas to go where ever I want whenever I want. It doesn't take much to get me to go on a road trip, I love to be able to just jump in the truck and drive straight out of town.<br /><br />

Originally posted by gonefishie:<br /> why don't they put a magnet on the bottom of fuel tank to hold onto the loose rust and stuff like on a tranmission oil pan?

Most stuff you might find in a gas tank is non ferrous and won't stick to a magnet. (rust, dirt, water..) Transmissions have magnets because they do have a bunch of metalic particles inside.

 

[Terry Olson]

Re: Keeping tank full vs refueling on E

I keep mine full rather than letting it run low for two reasons. First, as has been said, the fuel cools the pump making for longer pump life. Second, I too like the peace of mind that comes with a full tank should something come up - like is usually the case eh? <br /><br />I'm not sure these are really good reasons, but I can't think of anything that would change my preference to running with the tank low.

 

[craze1cars]

Re: Keeping tank full vs refueling on E

I personally think this is sort of like a "which oil is best" argument which has all kinds of fun theories and "yeah that probably makes sense" concepts, but never really has an answer.<br /><br />Me? I hate gas stations so I want to minimize the number of times I stop at them. So I usually run 'em till the low fuel light goes DING and then I top off. I've never run out, have never killed a fuel pump, and never had a problem with sludge suck. All my vehicles are kept for at least 150K miles. And my knuckles are KILLING me from knocking them over and over again on my oak desk here... <br /><br />Of course if I'm in unfamiliar territory I'll usually leave myself more of a cushion (I'm not THAT dumb!), but when I know for a fact that I've got 30 miles left in the tank, and there's 3 stations at the 3rd exit 20 miles down the road, I'm gonna push 'er to the limit and skip the next two exits...<br /><br />Plus the wife loves it..."OHMYGAWD!!!! WE'RE NOT GONNA MAKE IT!!!" Great fun.<br /><br />Incidentally, I've drained a large number of fuel tanks in my hod-rod building projects. I have never found anything but pure gasoline and maybe 3 or 4 sand-size specks of something in there...harmless stuff. And these are some OLD cars I'm tearing down with steel tanks, open vent systems, and no screens in the filler necks. So I honestly don't think "sludge" actually exists in a gas tank unless you've let the vehicle sit for years and the gas started to separate or absorb too much moisture causing the tank to rust from the inside....or some moron dumped a handful of dirt in there...<br /><br />And today's fuel tanks are plastic, fully sealed form the atmosphere, and have screens in the filler necks....so they should be rust-free and spotless. The cooling theory is a good one, but I think overblown unless you truly run it completely dry, and even if that happens most cars don't need an instant fuel pump replacement. They just need some gas and a bit of cranking!<br /><br />Just sharing my thoughts and experiences...obviously most here disagree....

 

[libaredneck]

Re: Keeping tank full vs refueling on E

just my 2 cents worth. ive been a mechanic 4 a long time. one main reason to keep tank full is its easier on the pump because of the head pressure of the fuel. it makes it easier to draw (manuel pump) and easier to pump (electric in tank pump)it takes some strain off it even if a little will make pump last longer. but im just a REDNECK so what do i know? huh? oh yea later REDNECK!

 

[ZmOz]

Re: Keeping tank full vs refueling on E

Originally posted by libaredneck:<br /> one main reason to keep tank full is its easier on the pump because of the head pressure of the fuel.

Definately. My old Jeep needed a new fuel pump, (electric) and it would go from making a light whining noise with a full tank to a horrible grinding noise with 1/4 tank. Obviously it didn't have to work as hard when it's full.<br /><br />The new pump I ordered arrived the day they towed the smashed carcass that was my jeep out of my driveway.

 

[Xcusme]

Re: Keeping tank full vs refueling on E

While we're on the subject of fuel ,tanks, and pumps, can someone for the love of Christ, please explain to me why auto makers put the pump inside the tank?? It would be so much easier to have the pump external with just a pickup tube in the tank. It's really a pain to drain/drop the tank spin off the pump collar and R&R the pump. A lifelong buddy still owns and operates a repair shop and tells me he's seen cars that have an access panel inside the trunk bottom to gain access to the pump without dropping the whole damn thing, now that make sense.