No matter what type of novel you are writing, action scenes are the key ingredient to keep your reader's pulse pounding and to keep them turning the pages. However, there is an art to an action sequence and a balance must be found. Too many action scenes in a book take the level of believability down while not enough can make the read seem long.
Overwrought action sequences leave a bad taste in the reader's mouth while half-baked sequences produce no reaction at all.
Remember your reader's attention span. Most action scenes should cover at least five to six pages of a manuscript, but they should not be drawn out. The period of action should have a believable beginning and middle and should come to a natural end. Don't stop the action just because you hit a certain point. The scene should flow until the action stops. If you drag out the action excessively, your reader's attention will wander.
Remember your tension levels. The necessary part of any action sequence is the tension. It should start out low and build gradually until it is resolved at the end of the action scene. An example of this would be a car chase scene. We see the main character is being watched and followed. Their speed accelerates; they begin weaving in and out of traffic until finally reaching a spot where they can duck away from their pursuers. This is a natural flow of events. If the car chase continues at a high level of tension too long, it becomes unbelievable.