Q: My friend's 2002 Chevy Astro van has a starting problem when it's humid or wet outside. I believe there could be a problem with the distributor cap or rotor, but I can't see the distributor when I open the hood. Do you know if this engine has a distributor, or does it use coil packs? --J.C., e-mail

A: J.C., the 4.3-liter V-6 engine in your friend's Astro van does use a distributor. But it's all the way in the back part of the engine bay and can only be accessed by removing the engine cover from inside the passenger compartment. Once the engine cover is removed, you'll see the distributor and can easily remove its cap for inspection. With the cap removed, you can inspect the distributor rotor, too. Make sure to check the spark plug wires and ignition coil, too. You can find the source of the trouble by running the engine and carefully spraying water (from a bottle) onto various parts of the ignition system, like the spark plug wires, distributor cap, and ignition coil. When the engine misfires, stumbles, or stalls, you've found the culprit. Also, carefully check the distributor underneath the distributor cap. There are two vents that are supposed to allow for ventilation, but they can become clogged and contribute to high levels of corrosion in the distributor.

Q: I have a question about motor oil. If motor oil gets dark in color with age, does it have any bearing on quality, or does quality diminish when oil is stored in a sealed bottle over time?-- S.S., e-mail

A: S.S., engine oil, even synthetic oil, is petroleum-based. Over time, the quality of petroleum-based products does diminish. If you open a container of oil and it appears darkened or discolored I would not recommend using it.

Q: I have a '99 Chevy Blazer with a 4.3-liter V-6 engine (115,000 miles); the one with the kind of electric carburetor - not the fuel injection. It starts and runs fine. However, when restarting the engine after it has been warmed up, it starts up okay and then it bogs down when trying to accelerate. I have to play with the gas pedal to get it to go. I've had a lot of things changed on it and nothing seems to help. Please respond.-- D.J., e-mail

A: D.J., your Blazer does have a fuel injection system. It's just different from most others. It uses a single, centrally-located injector, which sends fuel to individual (one for each cylinder) poppet nozzles. First, it's important that fuel pressure and volume be checked to ensure that the fuel pump is functioning properly. If the fuel pump is okay, I would suspect the fuel injection system. This system has been known to be problematic and may need cleaning. Find a repair shop (or take it to the dealer) that is familiar with this system. If things don't get better after a thorough cleaning/repair, and you plan on keeping the vehicle, a newer-style injection system can be retrofitted.

Questions for Ira Siegel? Call the Auto Adviser Hotline at 708-633-6839 or e-mail Autoadvisr@aol.comAutoAdviser. Ira Siegel is an Automotive Instructor and ASE Certified Master Auto Technician.