Can old gasoline cause an engine to not start?

Maintenance/Repairs
1

I have this old '89 BMW 325i and it just sits in the garage. I start it up once a month, and in the past 3-4 months it has been harder and harder to start it. This past weekend it wouldn’t start, just keeps cranking and cranking. Last fill up was about 6 months ago and it’s got 1/2 tank left. Can it be the old gasoline that’s causing it not to start? If I add new fuel, will that help?

2

try new gas and some plugs (drain the old gas out)

3

Yup…

What also may be happening is varnish. Gas that sits too long will create varnish and it needs to be cleaned out.

Try siphoning out the old gas and filling with fresh gas. Then use some starting fluid to get the car to start. Also add some techron gas cleaner or seafoam to the new gas. If it starts take it out for a run of 10-30 miles. I’d also recommend changing the sparkplugs because they may be fouled.

4

Yes, most definitely, the old gas could be the problem.

After you have all the old gas drained out, refill the tank with fresh gas and add fuel stabilizer. With stabilizer the gas should last much longer before turning to varnish. You should be adding stabilizer every time you fill the tank on this car.

5

Nope. Don’t blame 6-months-old fuel. Adding fresh fuel is unlikely to help. To prove my statements, get a spray can of QuickStart or equivalent. If your car still won’t start and run using the spray, your problem is definotely not due to old gas.

6

While I agree that ONE tank of 6-month-old is unlikely to cause much of a problem, this car ALWAYS has old gas in it, and sits around with the tank 1/2 empty for long periods of time.

This is a prescription for “stale” gas problems and formation of varnish in the fuel system.

7 
I don't think the gas is the problem.  I can't rule it out, but six month old gas should not be a problem unless it spent six months in the stations tanks.  

I would start with the usual causes.  Do you have spark for a starter.
8

Depending on the gasoline, it can degrade at any time.

About a year ago a car that would not even spit or cough when attempting to start it suffered from bad gas syndrome.
This car had been completely drained, fresh gas put in, and then allowed to sit for only 5 months.

It WAS the gas, no doubt about it.