If it only leaks when the tank is filled it likely has a leak on top, either where the pump is dropped in or in an emissions vapor recovery hose. My '88 Grand Caravan has been leaking from the pump seal for the last 15 years ever since my students pulled it out to clean the pickup screen. The symptom was when the gas station pump shut off I could nurse in another six gallons to fill the air pocket on top until gas ran out through that seal. That air pocket is supposed to form a crush zone in case of a crash. As long as I only add two or three gallons after the gas pump shuts off, there's no leak and no smell.
Check for a leak after driving a dozen miles. You may still see wetness on the sides of the tank but if nothing is dripping, that will dry off shortly. Have the engine running when you check for leaks. That way the fuel pump will be running. If you do see dripping only with the engine running, that points to a rusted metal fuel line or a loose hose clamp. I also developed that on my Caravan, and found all four hose clamps at the fuel filter were rusted away. That has happened twice thanks to Wisconsin's overuse of road salt. You'll want to have that looked at right away.
Answered by caradiodoc (expert)
Friday, August 16th, 2013 AT 11:51 AM