I just had my 88 out to the milage droped10mpg. The motor missed when over 3000rpm-motor dinot sound right, almost like it was getting to much fuel, the milage reading 99 mpg right i wish the instant said 0.one time to day the motor sound different the mpg said 34 then as quick as it changed it chandged back.no codes also the gas tank had persure when i opened it . we could smeel gas in the car . when i opened the tank you could here the air rushing out. I was thinking the cap should be vented

Black 88

 

88, this is really a tough read.

But I'm ganna take a stab here, for the gas smell...

Hole in gas tank - unlikely.

Plugged, or broken/disconnected vapor lines to evap cannister - more likely.

Leakin gas line - most likely. Turn the vehicle OFF, and do not turn the key on for 2 hours. Then turn it on, with someone else with you , and look for a leak. Check all the way from the tank, to the regulator.

Then pull the trigger, look for a leak from the regulator BACK TO THE TANK. QUICKLY. BEFORE THE EXHAUST HEATS UP.

 

Are you sure the air was rushing OUT?

 

I guessed it was air- not sure it ws not liguid but after i took the gas capp off the smell was gone for 10 to 20 miles. sometime it run perfect. when it is the running right it sounds likea pickup that is pulling a heavy load<this comes & goes think that it is in the fuel sytem some where, & . the tail pipe is black is there sommetime that could make it run rich.no feul under the car I just checked. Just put in new ecn

Thanks black 88

 

I'm tryin' to make sense of your words here 88, and it is really tough, I'm tellin' ya'.

Try to answer each question here, with no extra details.

What did it drop from, and to, when it dropped 10 mpg's?

This is an electrical problem. Gas smell is a mechanical / leak problem.

When the instantaneous said 0, that tell me that your VSS vehicle speed sensor is not working, unless you were NOTmoving.

YES, you do have codes. I promise. And you have vacuum leaks.

I have no clue about where to start to help you outhere 88.

You can get a free scan at some of the auto parts retailers. You have to do that first.

Can you park the car for a few days, and pull some parts?

 

I just saw your old 'cold start injector' questions again.

You HAVE TO get a scan done. You can get it done free at the parts store. Then we have a starting point.

DO NOT start buying parts blindly!!!

 

I would NOT worry about the sound of air rushing out of your tank when you remove the cap.

Every vehicle I have owned or borrowed does that. I believe it is because the fuel system is pressurized.

Have you changed your fuel filter yet? I know it is a silly question but I have a pet-peeve about crappy gas so I change mine out frequently.

As for mileage dropping.... Well I would suggest taking a look at your plugs. Fouled, burnt etc... These will be very telling as to what your problem may be.

Free scan/inspection can also be done at Carquest. They usually give you a printout of exactly what is wrong and which parts need replacing.

BTW: cwb is correct. Try to clean up your posts. Makes it very difficult to read if your typing becomes jumbled.

Multiple paragraphs are encouraged Not trying to be disrespectful. Please don't take it that way. Just trying to help.

Peace bro[sm=icon_cheers.gif]

 

Those posts are hard to read but I do agree with one thing - I have never had a vehicle that had as much vapor pressurized in the tank as the Corvette. I don't know what it is but it really spews when I go to put fuel in like no other car I have ever owned.

 

I see you online black88...

Whatcha got? Take your time on yer post now - no problem...

Did ya' get to plug in a scan tool at the auto parts store?

 

I believe you evap is plugged,(gas smell) and mabey severe vac. pooling fuel fouled plugs, how many miles? does it use oil??? feed us with the info we will feed you with the solutions