My question is about filling both my car and truck. I fill the gas tanks every week during my lunch break. I took my co-worker with me last week and he said not to overfill the gas tank. When the nozzle clicks stop, do not put any more gas in. I told him I can usually get another gallon in. He said this is not a good idea, but could not tell me why. Is this true and why?
QUESTION: My question is about filling both my car and truck. I fill the gas tanks every week during my lunch break. I took my co-worker with me last week and he said not to overfill the gas tank. When the nozzle clicks stop, do not put any more gas in. I told him I can usually get another gallon in. He said this is not a good idea, but could not tell me why. Is this true and why?
ANSWER: This is very true. When you overfill the gas tank you take a chance of damaging the evap system in the vehicle, both cars and trucks. All late-model vehicles have a charcoal canister that can be damaged when the gas tank is overfilled. Remember, the gas will expand with heat. You also never want to buy gas when the tank truck is refilling the underground tanks at the gas station. Third, always buy gas in the early morning or at dusk. There is less vapor loss during these hours.
QUESTION: I have a 1994 GMC Sonoma pickup four-cylinder auto, SLS, new engine, with about 25K miles, with an intermittent problem. Starts good, when driving from one to 10 miles it starts the following: speedometer goes erratic, service engine light comes on, brake light comes on, sometimes it backfires one or two times. It will downshift, upshift, go back to normal and then it may start again. I took it to the local garage. They kept it for a week, said they are not sure what the problem is, maybe the ECM/ECO/PCM unit, the TCM unit or the BCM unit. I don’t think they want to deal with it. Any idea as to where to start?”
ANSWER: My first step in this vehicle would be a physical check. This means remove, clean and secure all engine and body ground connections. To find all connections, the technician or you will need to look them all up in Alldata. The next step is a check of the power from the ignition side of the ignition switch. I do not think the problem is computer related.
QUESTION: I have a 2010 Mercedes ML350 that I bought new in February 2010. I was told to take it in for servicing November 2010, which I did. I was told that I did not need servicing for one year. I am concerned about changing the oil. I spoke with my mechanic, who always serviced my older car, and he said that since they use synthetic oil I should not be concerned. I also notice a hesitation when I start the car in the morning. It will not start when I insert my key. I have to do it three times before it starts. Should I take it in for servicing?
ANSWER: There is no question that today’s engine oil and other lubricating fluids are far superior than those of yesteryear. Some manufacturers like yours recommend an annual oil change, some even longer. We owned a 2007 E350 and that too had an annual oil and filter service. Under these conditions I like to see the oil and filter twice a year and this can be done at any qualified service center. As for the engine not starting on the first turn, this could be any number of problems including initial low fuel pressure coolant sensor out of range or a computer re programming. This will be covered by the manufacturer.
QUESTION: I have a 2007 Chevy Tahoe. Often the message comes up on the dash “Traction Control Off Service Stabilitrak.” When this message is flashing the vehicle seems to jump and pull slightly (kind of feels like something transmission). I have had it to the dealer twice to put on their computer and read the code. They have no solution. I Googled this problem and it seems this is common in Tahoes, but no one shared any solutions. Have you ever heard of this?
ANSWER: Before any diagnostics can be started the technician will need more information from you. What are you doing when the lights come on? Most of the time with this complaint the driver is applying the brake and coming to a stop usually around 10 miles per hour or less. If this is what is happening, the most common problem is a wheel speed sensor. The most common problem is a front speed sensor that gets contaminated with rust. You can also have your technician look on both Alldata and Identifix for information.
Junior Damato writes weekly about cars. You can send questions to him care of the Old Colony Memorial, 182 Standish Ave., Plymouth, MA 02360.