The 240DL '88 that my wife drives has been making a clicking noise in idle for a few months. It appears to come from the area around the rear axle and perhaps on the drivers side. We left town a few weeks back and let the car sit for 4-5 days. When I tried to restart the car it didn't want to hit. I tried until the battery began to get weak and then it finally started. She drives this car daily so the engine usually does not sit for longer than 10 hours before it gets turned over. I suspect I have a problem with the fuel pump or the little diaphram that prevents fuel from back flowing into the tank. I tried to sort out the FAQ on this but I was just more mystified. Could some kind soul please walk me through this? What do I look for to diagnose this problem and what do I need (replacment parts and tools) to repair this thing before it leaves my wife on the side of the road with a dead car. Thanks a bunch in advance.