Fuel spills out when I fill up.

Diagrams

https://www.google.com/search?q=1999+nissan+sentra+gas+tank+to+filler+neck

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it is unusual to have a filter in the filter neck as it would make it almost impossible to fill. There may be a device in the neck to stop fuel theft but not a filter. Run the fault codes and check for EVAP system problems

just one of those things , try holding the nozzle as far out of the filler neck tube as you can with out spilling the fuel or try with the nozzle up the other way a little bit awkward but does let the air out of tank without pushing fuel back up filler

Other than spilling gas on the ground when you are filling up, the check engine light should come on because the system is not sealed.

you have a "slow fill tank!" try filling it slower?

There is a check valve in the filler hose to stop fuel from coming out seems yours might be stuck , run a metal coat hangers inside the filler neck while prying open the little fill flap. see if that helps OR you are not or have no VENT to AIR in your evap system causing excessive tank pressure.

there is a restrictor in the filler neck so that if the car turns over no fuel spills out.you cannot remove it.
you will have to live with the slow fill rather than using
the auto fill gas gun......try turning the gun to one side....

Yes it's a common problem. You have two options: 1. fill the tank very slowly or; 2. (more tricky) put a short length of 3/8 fuel resistant PVC tubing down the filler neck before you fill up. make sure it is long enough not to disappear down into the tank & short enough not to reach the fuel when the tank is full. It is a good idea to hold onto this tube with you spare hand. Let any fuel in the tube drain out before removing it though & be careful not to spill petrol on yourself. To avoid this bend the tube gently back into the mouth of the fuel filler.

Sounds like you need a new filler neck. There is a vent, and it is part of the filler neck. Or there could be a bad valve at the bottom of the neck.

You will need to replace the filler neck, the vent hose inside the filler neck gets kinked and causes this problem. The air can not vent back out of the fuel tank as you fill it.