Bad/Old Gasoline
 

For fuel injected vehicels, what does old/bad gas DO to a car exactly? What are the physical symptoms of having bad/old gas? And if there's any damage done, what can be done to repair it?

I'm working on a car that has been running sporadically on and off again for the past few months and is still using the same tank of gas (aside from two gallons of new fuel being added about a month ago). Would adding fuel stabilizer work or is it better just to drain the tank and refill with new gas? And, what's the proper way to get that gasoline out of a tank anyways?


Sorry if this isn't making a whole lot of sense, I'm writing this at 1:20AM after working on said car for several hours!

My '89 Mustang sits a lot, in the past 2 years, it's been driven 650 miles. Some of that gas is probably 2 years old.
Now, it has a sealed system, and is garaged, so it doesn't go thru extreme temperature changes. I use no additives. It starts and runs fine.

how much gas is left in the tank? I would just try to run it until it is empty,then change the fuel filter,and fill it with fresh gas,at least that way if it still runs bad,you know it wasn't a bad fuel problem.

I think this is one of those "it depends" type of answers. It probably depends on how old the gas is amoung other variables.
A couple of years ago I wanted to mow some grass with a push mower. I ran out of gas in the mower and had none in the spare can. I then siphoned some out of a vehicle that had been sitting for about two years. The mower ran okay, but the grass wasn't too tall so the mower wasn't worked that hard. Anyway, when it came time to shut the mower off, it would not shut off! It continued to run despite not having any ignition to fire it. I then realized that it was running on bad gas. Not sure if I did any damage to the mower, but I'm sure it didn't help it any. It continues to be a good mower and I use it still....

Sea Foam Motor Tune-up from NAPA, CarQuest, Schucks,Checker, Kragen etc. will make the fuel burn acceptably and prevent further problems. It is a fuel stabilizer for up to 2 years.

Bad Gas has a characteristic smell, not sure how to describe it but once you smell it you know. It doesn't smell sharp like fresh gas, it smells kind of funky and not as harsh to the nose.

I had a car that sat for about 6 years and one day I decided to drain the tank and burn it in my daily driver. Big mistake.

The gas had a lot of sludge, as I discovered later, stupid me thought filtering thru some clean rags would do the trick. This sludge clogged up the fuel filter which caused my car to starve for gas.

The symptom on that car was that the car barely had enough power to get up to freeway speed. It ran smooth but had no power. If you floored it, it would go to high RPM but not make any power. At first I thought the tranny was slipping. Eventually I figured out that the computer was downshifting to compensate, thus the high RPMs, but there was still not enough power for me to feel the downshifts.

I changed the filter, ran some Techron and several tankfulls thru the car and it was fine.

The fuel stabilizers may be worthwhile, but I never tried them for longer than the winter season in the lawn equipment gas cans.

Good Luck,

Jim Henderson

Gasoline leaves a varnish behind with age. The biggest problem with FI engines is that if there's enough fuel left in the injectors over time, the varnish could clog the injectors. Fuel stabilizers help prevent fuel varnish by keeping the chemicals in suspension in the liquid fuel.

Is there any way to get the gas out of there without removing the tank?

The car has an access hatch underneath the rear seats that allows a person to replace the fuel pump without dropping the fuel tank so I guess I'll just siphon it out from there?

start it up, and go for a drive?


you could also disconnect the fuel lines at the tank.

Good luck
~Nate

Car won't stay started longer than a few minutes or else I would just go drive it all off. That's another issue in itself.

Disconnect the fuel line at the filter, and set up a power source to power the fuel pump in the tank, it should work to drain the fuel.

If it's disconnected at the filter will it just flow freely out till it's all drained with the key in the accessory position?

It's gotta be in the on position.

For that to work you would have to keep cycling the key on and off. The pump wont stay running. It only runs for a second or so when the key is turned on to prime the engine before it starts.