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View Full Version : Why are gasoline pumps sometimes slooooow?


R. P. McMurphy
09-05-2004, 06:11 PM
Occassionaly when I'm filling my own tank the gas pump will fill at an extremely slow rate. I'm squeezing the handle as hard as possible but it seems like the gas is just dripping into the tank.

I'm talking about modern pumps at a busy station. My guess it that the particular pump has a clogged filter but why would that be allowed to happen?

El Zagna
09-05-2004, 07:24 PM
This happened at a local station I frequent. Turns out it was a clogged filter.

silenus
09-05-2004, 07:35 PM
If it is at a busy station, my guess would be that the other side of the pump is being used, and there is a limit on how much can be pumped through the island at any given time. I have noticed that when the guy on the other side finishes, my side speeds up.

Mr. Slant
09-05-2004, 07:59 PM
This is a "me too" post, but when I asked the clerk at a Marathon station one time why it had been way slow last time I filled up, he said that the people working at the store were slackers and had probably forgotten to change the fuel filter in a timely fashion.
That was the LAST time I filled up at that particular station. I do not feel like replacing my fuel pump anytime soon.

aerodave
09-05-2004, 10:54 PM
I've seen stickers on gas pumps that said something about rapid temperature changes causing the pump to dispense much slower than usual.

So if you observe this happening after a bitchin' cold front moves through, that might be your answer.

However, I'm not sure what the mechanical reasoning for this might be.

Joey P
09-06-2004, 12:56 AM
This is a "me too" post, but when I asked the clerk at a Marathon station one time why it had been way slow last time I filled up, he said that the people working at the store were slackers and had probably forgotten to change the fuel filter in a timely fashion.
That was the LAST time I filled up at that particular station. I do not feel like replacing my fuel pump anytime soon.

Actually, if the fuel filter is dirty (I assume you mean the filter that cleans the gas BEFORE it makes it's way into your car). Then you shouldn't have a problem. As far as filters go (in general), the dirtier they are, the better they clean. All the crud caught in them, makes them less porus and they catch even more crud. If this is the case, you'll have to replace your pump less often. Less crud into your car, less crud going though your filter, and less crud making it's way to your pump.

Also to add. There is at least one station by me that's just plain slow. Always has been, infact it probably takes 50%-75% longer to fill up at that station. So possibly, they station you're talking about just has slower pumps.

asterion
09-06-2004, 08:00 AM
Sometimes it can just be how the nozzle is seated. I think it's a pressure thing, along the same lines as what makes the auto-shutoff of the trigger work. Try moving it in and out and see if you can find a spot that will make it work better.

t-keela
09-06-2004, 08:35 AM
I don't know about the clogged filter. I guess that could be one reason. Usually when the pump is really slow, you've got a pump that is vapor locked. Often you can let the pump sit idle for about 10-15 seconds which allows the vent to release the pressure built up inside the pump. (Due to more fuel being pumped out than the vent will release, a type of vacuum or pressure built up from changes in temperature)
Anyway, it will usually speed up after you initially squeeze the handle, release the handle then count to twenty. Now squeeze the handle again. The pump should pick up the fuel and start pumping at its normal rate.

BTW always ground the pump with your bare hand before fueling. This is normally done whenever you push the buttons or flip the lever or are holding the grip. BUT when you are wearing gloves, you don't actually make contact with the pump and therefore you may have built up static electricity which COULD start a fire.

lissener
09-06-2004, 12:57 PM
I find when I prepay a certain amount with cash, the last 10 or 20 cents of the countdown go VERY very slowly. This is obviously an attempt to make you give up and leave them the spare change; a little hedge on the profit margin. Because obviously the pump is capable of turning off at 00--some stations still do--so this is a pretty transparent attempt to rip you off a few cents at a time.

asterion
09-06-2004, 03:20 PM
I find when I prepay a certain amount with cash, the last 10 or 20 cents of the countdown go VERY very slowly. This is obviously an attempt to make you give up and leave them the spare change; a little hedge on the profit margin. Because obviously the pump is capable of turning off at 00--some stations still do--so this is a pretty transparent attempt to rip you off a few cents at a time.

Uhhh, no. This is set in the software controlling the pump and it slows down to make sure that it can't overrun. I'm not quite sure if the hardware and software controlling the pumps is inside the building with the rest of the computer equipment, but there is a delay between the action and the pump and the readout at the register; it generally goes in about 6 cent jumps when pumping normally. If the delay is similar to what is seen at the register, then it would make sense to slow it down for that last few cents. Unless you are willing to come in and pay for any overage that might occur without yelling at the cashier for the pump not stopping right at where it was supposed to (which happened to me quite a lot when an old valve wasn't closing properly, thus dispensing a few extra cents.)

Gary T
09-07-2004, 01:04 AM
Thirty-some years ago, with pre-digital pumps, I found that they could be set to run r e a l l y s l o w . In one instance, I mentioned it to the attendant, and he went to the pump and flipped a lever, restoring it to normal speed. In another, it was below freezing and I was using the self-service pump. I suspected they had purposely set it that way to "punish" frugal customers, so I stopped at 15 cents worth, paid up, and got my gas elsewhere.

Bongmaster
09-07-2004, 03:58 PM
From what I understand this is a pressure problem. Some kinds of pumps require a good seal from the nozzle to your tank. If there isn't enough pressure then you get a reduced flow. I have problems with my Explorer at certaingas stations all the time, others are fine.

Blown & Injected
09-08-2004, 12:35 AM
When it happens to me I just move to the next pump. Last time it happened to me, one of the station employee's was near by and I asked him WTH?
He just squeezed and released the lever on the nozzle about 10 - 15 times very quickly and the pump started flowing at a normal rate.

Now I actually cant wait until it happens again so I can see if it works at other pumps and stations.

Hup the Fool
09-08-2004, 03:37 AM
I don't know about the clogged filter. I guess that could be one reason. Usually when the pump is really slow, you've got a pump that is vapor locked. Often you can let the pump sit idle for about 10-15 seconds which allows the vent to release the pressure built up inside the pump. (Due to more fuel being pumped out than the vent will release, a type of vacuum or pressure built up from changes in temperature)
Anyway, it will usually speed up after you initially squeeze the handle, release the handle then count to twenty. Now squeeze the handle again. The pump should pick up the fuel and start pumping at its normal rate.


t-keela has it right. This usually happens when the person pumping the gas puts the nozzle in the tank, locks the handle in the on position and then turns the dispenser on. To avoid the problem turn on the dispenser, put the nozzle in the tank, wait for the dispenser to reset to $0.00 and then squeeze the handle.

As for clogged filters, I've changed a couple of hundred during routine maintainence and I have never seen one that was visibly dirty(other than being covered in gasoline) much less clogged enough to slow pumping. If someone told me their dispensers were slow because of clogged filters I would find a new gas station right quick.

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