Q: Our 2000 dodge durango tries to turn over, but won't start. We already replaced coils and spark plugs

The blinker malfunction is probably a coincidence. High fuel consumption could be related to the no start issue, particularly if faulty engine management controls, or sensors, are at issue. Basically, inasmuch as the car will just flat out not start at all now, the appropriate diagnostic is a no start diagnostic. If you request that service, the responding certified mechanic will get this taken care of for you. If you are looking at it yourself, what you want to do is download any OBD-II trouble codes that have been stored and examine those codes for diagnostic clues. Check for adequate fuel pressure, injector operation, and a spark at the spark plugs. Basically, if the starter motor is turning the engine over rapidly, at sufficient RPM, but the engine does not catch and run, that means that there is an ignition, fuel, air induction, or mechanical fault in the engine that will have to be repaired. Check for vacuum leaks, an air induction fault such as a stuck idle air control valve or, considering fuel, check for a failed temperature sensor that must be working properly to signal the PCM to enrich the mixture on cold start. Other possible no start faults are low compression, defective spark plugs, a defective coil(s), a failed crankshaft or camshaft position sensor, a failed throttle position sensor, and a broken timing belt. Regardless of the underlying cause, if you request the no start diagnostic the responding certified mechanic will get the problem diagnosed and repaired for you promptly. Please let us know if you have further concerns or questions as we are always here to help you.