Mystirious gas station question

[mafiosy]

I don't know if this question is appropriate for this forum, however out of desperation i'm trying to get help everywhere...
Ok here it is...

We're running a gas station (let's call it Sunoco) and this gas station has a weird problem, wich makes a maintanance of Sunoco just scratch their butts and "humm".

So..

the problem is that while using CreditCard on the pump the pump will suddenly stop at certain amount of 2 cents or 17 cents, and wouldn't pump anymore - if you restart the pump it will work fine.

(the pumps work fine mechanically and no problems when we preset the pump or just authorize to pump from the terminal. )

I have to mention that every possible circuit board was changed so as new terminal as well.

now watching the frequency of this problem occuring - i can clearly see that this only happens when at least 2 pumps are used.

one pump must be used as cash or authorised and second one (the one that eventually will fail) must be use as credit.

so if pump, that uses cash, stops exactly at same moment when the "credit" pump just at the beginning of the dispensing (2 cents,17cents) it will cut the "credit" pupm off. So somehow the terminal cuts the pump that is using the credit card off.

what is doing that?

any thoughts ideas or sugestions all are welcome!!
appreciated and valuated no matter what kind!

thank you!

 

[jrz126]

I used to work at a gas station, and we had a similar problem. If I remeber correctly, if the customer removed the nozzle first, then inserted the card, it would cause an error like that. It would say "invalid card use" when you viewed the pump.

Is the 2 or 17 cents charged to the card or do they have to pay for it with cash?

Where abouts are you located? I've noticed that most of the gas stations around here use the same company for their registers.

I also recall there being a problem if a pump was prepaid previously for a cash sale, then the next customer used a credit card it would cause a problem.

 

[Russlk]

I suspect that the power supply for the electronics of the two pumps is common. When the first pump shuts off, there is a transient that stops the second pump. Perhaps one of the filter caps in the power supply has failed or there may be a corroded ground connection.

 

[mafiosy]

1. no this is not that kind of problem that you had at the other gas station. while credit card is working fine - and actually while the same problem persist - the terminal shows that the pump is on and and no problem is indicated. The only sollution is to put the nozzle back and restart the pump. However the terminal register it as a regular sale of 2 cents and C.Card is getting charged for 2 cents.

2. Thank you for your wise reply - now about the ground connection - is that suppose to be in the circuit board or is there a separate ground for each pump? I'm thinking there should be a ground for the whole system if there is no order in which pumps shut down.

so

 

[Juglenaut]

If I owned a station and was having that problem for awhile I would end up just replacing the pumps and network.

 

[Russlk]

The only way to find a ground problem is to trace the wireing to see how it is connected. Disconnect and re-connect to see if that helps.

 

[mafiosy]

If I owned a station and was having that problem for awhile I would end up just replacing the pumps and network.

hehe no wonder that you're just a student - and one day you might even understand that if your car has broken down - you're trying to fix it and not to buy a new car! ( and that is ofcorse.. not to insult you )

I've traced the grounds to the circuit board - checked OK. pumps ofcourse are grounded by themselves as mounted to the ground.

now the terminal is grounded by a 3-ple plug into the socket.

weird huh?? :wink: