van will not start on 1993 GMC Vandura 2500

Van stopped running can not start it. When turning ignition on there is no spark, when turning ignition switch off the engine continues turning over until i disconnect the battery. I have checked the alternator, it reads good, replaced the ignition switch still no change. Can not see any crossed wires and am about to check the starter motor coil. I had replaced the distributor cap a couple of weeks ago and rotor when van had broken down previously to this breakdown. The engine started up first time but it was missing. I may have not got the wires in the correct order. I have now put new plug wires on but am not certain how to read the way they should be put in order from my Chilton book instructions as i am seeing the firing order but can not determine definitely where the starting place is for the first plug wire as the cap is not marked. I had major water leaks going down behind the fuse box as this vehicle had been very badly maintained and will check that area too. Can not determine why the engine tuns over when i turn the ignition switch off and why it will not start. Also checked the distributor relay which is good. Help please.

Asked by for the 1993 GMC Vandura 2500
Lets begin with the Starting problem. It could be the solenoid inside the starter is sticking because the hold-in coils are shorted and won't let go which means that your car will crank forever. As for the other issues, a water damaged fuse panel could cause 1 heck of a lot of problems. Do you have power at the Ignition Coil?