My car doesn't like 91

[drbassbmd]

hey guys i did a very stupid thing the other day. I went to the gas station and put 91 in my nova. ran pretty good for a day next day i saw a big decrease in performance. now i can't go down the street with out it stalling.

[Indetrucks]

What did you run before? VP red 112 octane ?

[drbassbmd]

No I was running 87. any ways to fix it?

[Indetrucks]

Somethings wrong here... If you were running 87 and now have put in 91, It should be running a lot BETTER! First thing I would do is check and see if they sell Diesel at the gas station you filled up at. Because the only was your car should run worse is if you went from a higher octane like 112 down to 91 because you have high compression. In my personal opinion either A: You accidentally put Diesel in your car or B: It's not the gas and merley a coincidence. that your car started to run worse right after filling up.. What year nova is it?

[drbassbmd]

its a 1970 307ci. They don't sell Diesel at that gas station. I figured if 91 was the same price as 87 a month ago then i would start putting in 91. Also i heard that 91 has less air so it doesn't burn as fast give more mpg, but I think its to thick for my carb I dont know what the hell is worng with it.

[nova68]

it not the gas something wrong is with your car?

[Indetrucks]

I agree.. Unless the gas you got was contaminated I.E water in it then it's your car. Take a sample of your gas if you really think it has something to do with after filling it up. Put the gas in a glass jar and you will be able to see the water seperate from the actual gas. Higher Octane in some instances will cause better gas milage but more importantly it burns hotter and cleaner causing just about any car to run better.. In no way have I ever heard of 87 octane out performing 91 octane. Might want to get a fuel sample just in case.. Last time I checked gas prices havent been dropping.. well at least not here in California.. Where are you located and was it a reputable gas station? Or was it one of those cheap off brand stations? You never know..?

[drbassbmd]

I live in cali too im in the inland empire area 87 was 2.39 at one point i just got it at arco for 2.03. When i got the 91 I got it from Albertsons i paid like 2.30 or 2.27 for it. the car ran fine before i put the 91 in. most likely is my car but the 91 must have caused it. You know when you push on the gas when the cars not on and you'll flood ur carb well i was under the hood seeing if gas was getting to it and there was only one steam then no more. before I could pull it and make gas come out fine.

[drbassbmd]

im up

[Indetrucks]

Your Up? as in problem fixed? What was it?

[drbassbmd]

no I still have the problem i said im up so it would show me online then i figured out that I can sign in and it will show me that im online.

[Indetrucks]

Here is the next step if the Gas isnt contaminated I.E. Water. Check that your fuel pump is working correctly. A lot of times on cars with this age the diaphram in them goes bad. They are cheap and easy to replace, About $30 at local auto parts store and maybe 30 minutes to an hour to install. Located on the side of the block. So if you're not getting gas and your jets/carburator are ok, then check the fuel pump.

[drbassbmd]

well I can get it start and now the fuel is gettign to the carb. I turned the engine on and I turned it off and now i have gas going to it. I had a hard tiem starting it up and i saw smoke coming from the engine. i turned it off checked it out saw nothin. started it back up then i got it going but it was shaking really hard. more then it used to. it never did that before. I still have the same problem if i try to gun it will stall

[Indetrucks]

It sounds like you need to start with just the basics. Running rough like that could be many many things. Gas could be contaminated and or spark distribution may be insufficient? We can go on and on about things to check but start with the basics. It's probably not as bad as you think. As far as smoke from under the hood? Could be valve covers leaking a little bit of oil onto your exhaust manifolds/headers then burning off... sounds interesting..

[big dwag]

what kind of motor oil do you run in it, if the oil dosen't have HD in it then your intake will build up carbon under the pan on the bottom side of it, and it will make it stall and it will not want to run right. it happen to me when i went from a two barrel to a four barrel intake.and i had the same problems that you are having. all i had to do was to take it off and pull the pan off and clean it out and put everything back on, and it ran good and it still running strong.