exitwound

The vent pipe that runs from the tank to the charcoal can rusts out as it is held in the brake pipe bundle down the sill. I dumped mine and replaced it with a roll over valve at the tank that allows the tank to breathe yet shuts off if I'm inverted. That pipe either rusts open or blocks and its easy to check.

93Rubie

OP, this is the best answer you have got so far.

In fuel injected cars a bad gas cap WILL NOT cause it to starve for fuel. WE GAVE UP CARBS DECADES AGO PEOPLE GET OVER IT!!!!

I've NEVER seen a gas cap stick shut and not vent and form any kind of severe vacuum. Even if it did, your plastic lines and crap would break before it hurt the tank.

Your OBD2 tool not likely work with your 94.

OBD1 cars (pre-96) can run like crap and NEVER set a code. Post 96 cars can run like crap and not set a code for that matter.

If you don't want to throw parts at it you need to spend time and some money on:
1. Learning the system--> FSM
2. Investing in tools to do testing.
3. Doing the tests and reporting results so we can help you.

Option 4 is taking a WAG and throwing parts at in HOPES of fixing it.

Your choice.

As far as learning goes here is a free source. I also happened to create it.

antfarmer2

Just a wag but your o2's are 20 years old. You have 3. I would replace the front two. I know some will not agree. But $50 worth of parts is maintenance. I agree that a good scanner would be better but will cost more. It is your car and your choice.