There's a front-wheel-drive and a rear-wheel-drive 5th Ave, and we need to know which engine you have when discussing an engine running problem. Based on your comment about the Engine Computer on the air filter housing, my guess is you have a 318 c.I. In the rear-wheel-drive model. If that's right, check for spark at the coil wire, and watch it when a helper turns the ignition switch off. If you see one spark at that time, you'll know the ignition coil is okay. The computer could have failed but it's much more likely the pickup coil in the distributor is defective. Some models have only one of those. Measure it for continuity. You should find in the area of 450 to 750 ohms. Typically, if they're defective, you'll find they are open, not just the wrong value.
Some models have two pickup coils, one for starting and one for running. You can try switching the plugs so it will start on the "run" coil. If the engine runs as long as you hold the ignition switch in the "crank" position, suspect the other pickup coil. Next, switching between the two coils is done with a relay. The contacts could become pitted or corroded, then one or neither coil could work.
If you have the front-wheel-drive model, a real common cause of not starting is the Hall Effect switch in the distributor. That's real easy to replace. It's a disc that sits under the rotor, and has a three-wire plug.
Thursday, October 17th, 2013 AT 10:59 PM