i have an 88 d150 4barrel. was driving it for a few miles and someone at the light told me i was leaking something...... turns out to be fuel (as if the gas mileage isnt bad enough ha). got it home and there was a steady stream coming from underneath. i cracked the gas cap and there was alot of pressure built up. leak stopped after that. anyone had this problem? solutions? thanks in advance

 

try getting a vented fuel cap. and also try to find the source of the leak.

 

X2

There should be a vent tube on the tank to prevent that from happening or an EVAP system that collects the gas vapors and purges them into the motor during cold startups. Either way, the vent system is clogged and you need to unclog it. You also need to find the leak and get that fixed.