How to investigate bad gas

I have a 2001 ford mustang with 65,000 miles. I got gas last wednesday at an El Paso, TX Diamond Shamrock; the next day my check engine light went on; I took the car to the dealership who replaced a sensor and the light went off; a few hours later the light went back on, I returned it to the dealer where they adjusted a hose; the next day I had trouble starting the car; I had it towed back to the dealership where they could find nothing wrong; the next morning the car wouldn’t start so again I had it towed; the dealership determined that I had bad gas and the system had to be flushed and the tank cleaned and a sample of what was in the gas tank was saved.

I know what Tom and Ray say about the consistency of gas quality and I have read the discussions about bad gas.

Who regulates gas quality? How could I find out if there have been other bad gas claims in the area?

have you called and asked the gas station manager/owner? see if they stand by the quality of the gas they sell.

the sample of gas could be tested for its flash and flame point. also its octane level. but… the dilemma is that the tests and samples must be ‘run’ by an accepted gas lab. you have already jinxed that because someone else took the samples.

the problem is that it has already been taken out of the car. it would be highly unlikely that any gas station would accept the statement: “trust me, it came from my tank which came from your station” then this becomes a he said, she said situation.

but, yes it can be done. probably will cost you more to carry on than the repairs will cost.

I would suggest contacting your Office of Consumer Affairs (NOT the Better Business Bureau), which is either a state agency or a county agency, depending on your state.

Also, in many states, the Bureau of Weights and Measures regulates the sale of gasoline–both in terms of gas quality and the measurement of the gas that is sold by a gas station. Either or both of these agencies should be able to tell you if there have been other complaints regarding that particular gas station.

Just check at the place where you bought the gas.  Usually truly bad gas is a limited event.  Sometimes a loose pipe lets water in for example.  They may pay for the repair cost.  The one time in over 40 years of driving that I got bad gas, Exxon paid the bill with no question.  I was not the only one that had shown up after getting gas there.