I have a mastercraft compressor with LCD display its 11 gallon,it runs up to about 70 psi and will not go higher but keeps running, any ideas.

You either have an air leak somewhere or you have a damaged valve in the valve body. You can check for leaks using a spray bottle with a dishwashing detergent/water mix. Spray the mixture on connectors and look for bubbles. Don't forget to check the tubing coming from the compressor head and the regulator. If you find no leaks (you need to check carefully), you might need to remove the compressor head and check to see if the valves in the valve body are damaged. My Campbell-Hausfeld compressor did the same thing and I had to replace the valve body.