Q: Cannot get plug off of water pump in 94 Buick Lasabre.

Try taking a small torch to the top of the plug and heat it up. Then take liquid wrench and spray the threads and let it sit for about 1 hour. Then you will need to use a hammer and punch and tap on the plug, about 4 to 5 times. This will free up any debris, corrosion, or rust on the plug. Then use a long breaker bar and a socket - if you can put a socket on the plug - and remove the plug. A wrench and a long bar will do the same, but be careful not to let the wrench slip off the bar. If you need further assistance with your water pump plug, then seek out a professional, such as one from Your Mechanic, to help you.