symptoms of running a car onold/bad gas?

911-m5 · 09-26-2005, 04:18 PM

My car has been sitting a whle and its spitting through the carbs and an occaisional cough from the exhaust. Just wondering if this could be the culprit. However, now that I think about it, it runs fine when I first start it up - about 30 secs to 1 min before it starts objecting.

thanks

wholberg · wholberg's Garage

Bad gas, as in old, causes symptoms like knocking and reduced power from reduced octane.

Water in gas might cause the symptoms you describe, but so could carbs with a bunch of internal varnish and crap from sitting. I would start with the typical tune up stuff, cap, rotor, etc., and if that does not fix it, clean the carbs.

Bobboloo · Bobboloo's Garage

Wouldn't hurt to change the fuel filter and add some gasoline stabilizer.

Navaros911 · 09-27-2005, 01:33 AM

911-m5: How long is a while?

How long would it take for gas to go bad? 3 months, 6 months, a year?

Mine has not moved for 2 months (slow suspension project - for various reasons - and a bunch of 'while I'm in there stuff') and wonder if that is a problem.

livi · 09-27-2005, 02:08 AM

As Bobboloo mentioned - fuel filter.

At least a few earlier threads have described there could be a connection with symptoms like this - noticeable first after running for a short while.

Experts aboard - am I learning anything yet ?

wholberg · wholberg's Garage

Quote:

Originally posted by Navaros911
911-m5: How long is a while?

How long would it take for gas to go bad? 3 months, 6 months, a year?

Without stabilizer, gas can go bad in 4-6 months, as in loss of octane, not necessarily condensation in the tank. Carbureters usually take a little longer to gum up, unless the car is not run very much.

Fuel stabilizer slows the loss of octane, and prevents water from pooling in the bottom of the gas tank, causing rust.

murphyslaw1978 · 09-05-2006, 10:45 AM

Mr. Wholberg - my '88 Carrera was sputtering and missing at 1/4 tank. I filled up and the problem disappeared. I don't think I was out of gas (filled up 18 gallons and tank is 22.5 gallons), but I do think I have some water in there. Which product - specifially - do you recommend to put in the tank and run it through? Are they all safe to use or just STAY-BIL?

petrolblue83911 · 09-05-2006, 10:55 AM

Look at the fuel filter for sure, sounds like the classic symptoms of the fuel lines dragging crap up from the tank and lines and into the filter. When starting the car at first, the crap has settled so it takes a few seconds/minutes for it to come back up. If you find your filter badly clogged you may need to either pull the fuel line and pump the tank out into a conainer to rid the lines of the crap, or -worst case, pull the tank and clean it out.

murphyslaw1978 · 09-05-2006, 11:18 AM

I actually did replace the air and fuel filters before my trip. I ran the car afterwards and it ran fine. It only seems to be an issue when I hit 1/4 tank. The old fuel filter didn't look clogged or too dirty.

wholberg · wholberg's Garage

Quote:

Originally posted by murphyslaw1978
Mr. Wholberg - my '88 Carrera was sputtering and missing at 1/4 tank. I filled up and the problem disappeared. I don't think I was out of gas (filled up 18 gallons and tank is 22.5 gallons), but I do think I have some water in there. Which product - specifially - do you recommend to put in the tank and run it through? Are they all safe to use or just STAY-BIL?

I had an old Camaro that exhibited identical symptoms, and the cure was the same, new gas diluted the old gas and the car ran fine.

If you think you have water in the tank, add some Heet, or whatever the auto parts stores sell for removing water from the tank. The kicker is that it might be difficult to find in the summer. Water removers are normally either methanol of isopropanol, if you have access to either one of those in pure form, about a pint in a tank of gas should work fine.