pretty much the same as a bad fuel pump except it happens infrequently. it'll turn over strong but won't crank. the simplest way i know of to tell is when you turn your key to the position right before it cranks the CEL comes on, when this light goes off youll hear a click from under the dash, thats the relay coming on. if you dont hear the click the relays not working properly and your cars not going to crank. I hope that makes sense, if not i'll try to reword it.