At least in New England, when you’re filling up your fuel tank, the pump usually shuts off at $75. With a diesel truck and a 38 gallon tank, it’s a PITA to put the credit card back in and start the pump all over again.
I asked my card companies (Chase and Citibank) if they were the ones setting it. They denied all knowledge. I asked several station managers and they denied all knowledge.
Anyone know the Straight Dope on how this limit is set and how to get it changed?
I ran into that problem when gas was $4.75 18 months ago. I’m pretty sure $75 is the amount they pre-authorize.
The station doesn’t know how much you are buying. They charge the card for an amount (say $75). After the pump goes off they release any unspent money.
I’ve run into problems with a debit card. I’ll have perhaps $40 in my account. Go get $20 of gas. The card would decline at the pump because it couldn’t get the $75 in reserve. I could go inside and tell them I wanted $20 of gas and the card was approved.
It’s set by the guy behind the counter, at least in an independent station.
When gas hit it’s peak around $4.00 a gallon here, I actually swiped my card twice and still didn’t get the tank completely full. They had it set at $50.00.
The second time I filled up, I went inside to talk to the guy behind the counter (I’m a regular customer at this particular station) and within about a minute, he changed it to $100.
I wonder now if he’s lowered it again since regular gas is only $2.35 there now.
Yep, the preauth amount is indeed set by the merchant. They want to ensure that you have enough money in your account before actually pumping the gas. Think of it like prepaying $80 with cash; you’re not actually *giving *the gas station $80, they’re just using it as collateral in case you pump $80 worth of gas. With cash they typically give you back your change. With credit cards it’s a little different. What is supposed to happen is the station preauths for $80(or whatever amount they choose). Once the bank verifies the customer has $80 in their account it’s supposed to null that transaction and then let the customer pump. Sometimes that preauth doesn’t clear right away for some reason and it can cause problems later, but it’s rare that happens at all. That’s why you may see a ‘pending transaction’ if you check your online bank statement later in the day.
Now, the independent stations can change the amount they preauthorize easily, it’s just a software setting. With chains, those are set at the corporate office and typically can’t be changed on a store to store basis. It’s certainly possible to let the stores set their own amounts, but have you SEEN the people that work in a gas station? 
I worked for a gas station helpdesk for 5 years, I got to fix computer problems when Things Went Wrong. When the gas prices were above $4/gal we changed the amount to $150 for all the stores. Once it dropped it went back down again.
They could resolve that by letting you guess how much you’re going to pump, typing it straight in, and then stopping you if you go over. Then each customer could set how much they need.
I know they can do it, since they do it inside all the time.