TNcorvette89

Hello all. I have a 1989 vette that is bone stock with 52000 miles. It has developed a curious issue I have no idea what the cause is. The car feels like it misses some at low speeds between 35-40 MPH. Then when you get to highway speeds it feels like it is missing more 65-70MPH. There is also a tremendous amount of pressure when you open the gas cap. There has been an occasion that the car completely quit running and after relieving the pressure it began to run again. I have talked with the corvette guru in town and he has never heard of this issue before.

AGENT 86

If there is pressure in the tank, I would look at http://members.shaw.ca/corvette86/Ev...l%20System.pdf

rons85

Pressure in the gas tank can happen - and Will happen with slow speed cruising on a hot day. At slow enough speeds the charcoal canister/purge/vent valve won't be open (I forget the numbers, it's in the FSM, which is at home..) and the tank won't be vented. This is not a Corvette specific thing, it's across most '80's and '90's vehicles that still have emissions legal non-venting cas caps on them.

You can either "fix" the gas cap to allow pressure to escape from the tank (most emissions testing checks that gas cap though - it'll fail..) or you can eliminate the purge valve to allow the tank to vent through the charcoal cannister at all times. This can be a dangerous idea though - fuel fumes can collect in the engine compartment on a hot soak condition....

Or live with it - it's "normal".

TA

I've read enough posts over the years to make me believe its somewhat normal. I know my car has done as long as I've owned it (8 years).

anchami79

I agree, I've owned my '85 for the last 8 years and every time I fill up the tank it hisses at me. I'm so used to it that if it didn't have any pressure, I'd think something was wrong!

I'd check elsewhere for the miss.