Q: I have a 2001 Chevrolet 1500 van with a V-8 engine (97,000 miles). I’ve kept up with all the service maintenance. The van is in very good condition. Now, in the morning, the van needs two attempts to start it up. Once it’s running, it runs great with no problems. I can turn it off and it starts right up, until the next day. Then, it’s hard to start again. What could be causing this problem? – Joe, e-mail

A: The first thing I would check would be fuel pressure. Fuel pressure should be maintained in the fuel line and fuel rail (up by the engine) with the engine off so there will be fuel available to the fuel injectors when restarting the engine. The extended cranking concern you have could be the result of fuel pressure dropping off overnight. This could happen if the fuel pump’s internal check valve is beginning to fail. The fuel pump’s internal check valve is designed to keep pressurized fuel in the fuel line and fuel rail. When this check valve fails, it can allow fuel in the fuel rail to bleed back to the fuel tank. Since your truck starts right up after it’s been driven, I believe the check valve in your truck’s fuel pump has a slow internal leak. This can be confirmed by installing a pressure gauge and watching it over time. Of course, leaky fuel injectors could also cause fuel pressure to bleed off. But if that were the case, you’d have trouble starting the engine when it was warm, too. Since the problem only occurs after it has sat overnight, I’d suspect the fuel pump check valve. By the way, you can’t just change the check valve. It comes included with a new fuel pump. The fuel pump in your van is mounted inside the fuel tank, requiring removal of the tank to replace it.

Q: I have a 2003 Buick Rendezvous. The problem is that the AWD disable light is on all the time. I had the front hub assemblies changed and the fluid level checked in the power train unit and rear differential. A scan tool test revealed no stored diagnostic trouble codes. Do you have any recommendations? – M.G., Chicago

A: Yes, I do have a recommendation. First, check to make sure all four tires are the same size, have about the same amount of wear and have the recommended air pressure. If you have two new tires on one axle and two old tires on the other axle or there are different sized tires, the all-wheel drive system will be disabled. It’s also possible that the scan tool that was used only reads codes from the powertrain control module. Take your Buick to the dealer or a shop that has the “Tech 2” factory scan tool. That scan tool will help the technician determine if there are any drivetrain related codes and if the AWD system is being disabled due to an over-temperature condition of the rear-drive module.

Q: I’m the second owner of a 2004 Acura TSX and it has about 115,000 miles on it. A friend of mine said that the engine’s valve clearance is adjustable and should be checked and/or adjusted. Do you know if that’s true? – S.C, Chicago

A: Yes, it’s true. According to Acura, the TSX model’s valve clearance should be inspected and/or adjusted every 110,000 miles.

Questions for Ira Siegel? Call the Auto Advisor Hotline at (708) 633-6839 or e-mail autoadvisr@aol. com. Siegel is an automotive instructor and an automotive service excellencecertified master auto technician.