I have a 97 chevy s-10 blazer 4.3l v6 vortech with 137,000miles. i have started having problems with the fuel pump turning on.i started having this problem a while ago and it got worse to the point that it just dosent come on any more. when i turn the key to the on position the caution lights that should turn on for a split second then go off,dont turn on, nor do the gauges work, and the fuel pump dont prime but the vehicle will crank till the battery goes dead. i changed the fuel pump relay and both ecm batt, ecm eng fuses. what could be the problem?