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Anthony, Chevy Technician
Category: Chevy
Satisfied Customers: 11808
Experience:  GM Certified
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1985 Corvette TPI engine. I let this car sit for about 2 years.

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1985 Corvette TPI engine. I let this car sit for about 2 years. Was running fine prior to this, no misses, it ran fine. After sitting for 2 years, the gas went bad and fuel pump went out. I have replaced the fuel pump and the strainer and it's starts and runs, but is very rough and misses, though not a regular miss. Engine runs but stumbles and backfires some. I put 3 cans of Seafoam and 15 gallons of fresh gas to the gas that was in the tank, hoping that would clear out whatever might be gunking it up. Any suggestions on where to start. Pull the injectors and test and clean? Am about to replace the fuel filter. Would like to know the typical things to do/check/replace so I am not chasing my tail trying to figure out what is causing the problem. Thanks in advance for the help.

Hello! Welcome to justanswer!


I have an 85 myself so I know this is possible. Try siphoning about 2 gallons of fuel from the tank. Make sure the siphon is on the dead bottom. I think you have water. Also after you siphon the fuel, take a sample and see if you have water by letting it separate in a glass. Water is on the bottom so a siphon will get it. Also replace the O2 sensor and take it for a long drive. Another part that will make it run terrible is a bad airflow sensor. If you have no water and a good O2, try another Airflow Sensor.

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Customer: replied 7 years ago.
I can try that. It may have accumulated some water. What I noticed when I first went to start it, before I realized the fuel pump had died, was the gas smelled extremely toxic, not like normal gas. Since it wouldn't start, I poured a little gas into the throttle body and it ran awesome until the gas burned off. So, I replaced the fuel pump and then it started but runs like crap. It barely runs and keeps dying. I guess what I'm getting at is that I think there was about a 1/4 tank of really toxic gas, some auto parts guys are saying it turned to Kersone? How to figure out if the old bad gas is doing this? I just don't want to spend the next however long trying umpteen different things. Anyway, I'm off to the parts store to get a siphon hose. I also noticed my gas guage now reads full. This was before I filled the tank with another 15 gallons of good gas. I had pulled the unit out again to see if I had somehow hung the float on something, but it isn't hanging up. This bad gas is wack. Anyway, any other input you can give? I'll be back shorlty. Thanks.

Think of it this way if you had a 1/4 barrel of sewage and you added 3/4 barrel wine to it, what would you have?

Customer: replied 7 years ago.

This is my first time trying this Just Answer service. Can answer more questions? How does this work? It seem to be idling ok, but when I step on the throttle, it stumbles badly, like it just ran out of gas. Idles fine, but step on it and it wants die. I'm starting to think I have more than one thing I'm dealing with. If I tap the throttle repeatedly, the rpms come up, but if I just step on it, it stumbles and coughs. It feels like once when my MAF went out.

Try tapping on the airflow sensor, does the engine stumble if you do?
Customer: replied 7 years ago.

This thing is being such a pain. I had it idling while I was in the house. Went back out and it had died and won't start. It's been doing that. It's been starting once the engine gets a little cool. I''ll try it again in about 15 minutes. This thing used start right up. Now I"m having to crank it a long time and it kind stumbles into a start. How long are on tonight? It will probably be about 15 minutes before it will start for me.

Ill be here. Get it runnnig and tap the sensor and see if you get reactions from the engine.
Customer: replied 7 years ago.
It's definitely the gas. I don't know if it has water or not, yet, as I haven't siphoned the gas out. I hooked up an external fuel pump to some good gas and it ran almost normal. Still rough, but a zillion times better. Now, what do I do with the 18-20 gallons in the tank? 4-5 gallons is the old crap gas. What do you recommend on how to get rid of the gas in the tank? Run it through one of my other cars? Take it somewhere and recycle it? I don't have anything to transport that much gas.

Its hard to say but you got to get it out of the vehicle. Any oil change shop will take it and mix it in with their waste oil. Do it 5 gallons at a time. DOnt run it through any of your other vehicles as it may damage something.