Changed gas, car runs like crap - Vintage Mustang Forums
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post #1 of 7 (permalink) Old 06-16-2019, 03:51 PM Thread Starter
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Changed gas, car runs like crap

I dont have enough garage space to park my 65 at home, so its a mile away in a storage locker. Once I sell the 67, the 65 will come home.

Since Im only driving it on weekends, its hard to start when I take it out of the storage facility on Friday afternoon.

Once I get it started, its fine all weekend.

Im guessing that the gas is evaporating out of the carb.

This Friday I went down and put 8 gallons of ethanol free gas in, 89 octane, I usually run 87 octane with 10% ethanol.

Car runs horrible. it dies whenever I lift my foot off the gas, idles rough.

So much for paying 75 cents a gallon more for the good stuff.

1965 Mustang Coupe 289/C4
1967 Mustang Coupe 200/C4
2017 Mustang EB Premium
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post #2 of 7 (permalink) Old 06-16-2019, 04:08 PM
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The good stuff here is 91 octane ethanol free and it costs 50 cents per gallon more than 87 octane with up to 10% ethanol.
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post #3 of 7 (permalink) Old 06-16-2019, 04:20 PM
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I feel privileged. We have some stations with 93 octane ethanol free but you have to know where they are because there aren’t many. The few stations that have ethanol free will either have all grades ethanol free or just the premium. Some have premium as 91 and some as 93. It’s usually an extra $1 per gallon for the premium ethanol free

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post #4 of 7 (permalink) Old 06-16-2019, 06:39 PM
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Here in the wilds of PA, I use 93 in Diane, and 94 when I can get it. It's over $3.50 per gallon right now but she doesn't like anything less and lets me know by coughing and spitting. The PO used (gasp!) 87, I think. In a 4v no less! She's much happier now.
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post #5 of 7 (permalink) Old 06-16-2019, 07:27 PM
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OP...sounds like something got gummed up in the carb while sitting for a week.

I've started a blog about my car and adventures:

1965 Fastback, 289, Toploader 4 Speed, owned by me since June 1980. Originally a C-code with a C-4. 5R09C16****
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post #6 of 7 (permalink) Old 06-16-2019, 09:51 PM
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Fuel doesn't evaporate that quickly from an enclosed bowl. I suspect, the fuel pump diaphragm is bad and or you picked up a bad load of fuel (water).
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Ken ..
64 1/2 Poppy Red Cvt. Resto-Mod
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post #7 of 7 (permalink) Old 06-17-2019, 01:50 AM
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If that non-ethanol fuel is not a big seller and it has been sitting for a while, you might have picked up trash that has gotten through the filter and into your needle and seat. Or using ethanol fuel all the other times may have degraded a rubber part that has done the same. It might be something you can clean out or something that may come out with some driving.

'66 Tahoe Turquoise/ Aqua coupe
•289 / 4100 •C4 Auto •Disc Brakes
•Dual Exhaust •16:1 Manual Steering
•Rally Pac •Console •Deluxe Belts
•LOTS of Rotunda accessories
•Original Styled Steel Wheels first car

'66 Emberglo / Parchment coupe
•289 / 2100 •C4 Auto •Disc Brakes
•Dual Exhaust •16:1 Power Steering
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