Fuel system may be losing pressure

By Doug McAllister

Q. I have written you before and you have been a big help in keeping my car running. I enjoy your column in the Daily Herald.

My car is a 2000 Type S Jaguar that I bought two years ago, now with 83,000-plus miles on it. I flew in from a vacation last Tuesday and I drove the car that evening. It had been in the garage for the previous five days. I kept the car outside overnight in the driveway. On Wednesday morning, the outside temperature was about 17 degrees. When I tried to start it, it would not "catch" for four tries.

I stopped trying to start it and got a towing business card out of the glove box. Before I called the towing service I tried starting it again. It started and has run fine ever since.

A little information that may help you determine why it may not have started. I had backed into the driveway, which sloped about 15 degrees so the front of the car was lower. I had about a half a tank of gas. There was no "check engine" symbol so I assume it didn't leave a code.

Is this something that one has to wait until it fails or is there something that can be done to prevent a non-start in the future. Thanks for any advice you can give.

A. It's always tough to say what's going on without experiencing the problem firsthand. However, from your description, it sounds like you may have a check-valve problem in the fuel system. I'm not sure where it is on your Jag but most of the time they are part of the fuel pump assembly.

The check valve will keep the fuel from running back into the tank. The fuel lines and rail should remain pressurized so the vehicle will start right away. If it had to build pressure, this would explain several attempts to start as the fuel line would need pressure to build back up.

This is not the only possibility but it is what came to mind based on your explanation. The next time it fails to catch, rather than trying to start it, cycle the key from "off" to "run" two or three times to prime the fuel rail. Then try to start the car. If it starts right away after that, you may have your answer in that the fuel system is losing pressure.

• Douglas Automotive is at 417 W. Main St., Barrington, (847) 381-0454, and 123 Virginia Road, Crystal Lake, (815) 356-0440. For information, visit douglasautomotive.com. Send questions to underthehood@dailyherald.com.