Q: 98 Chevrolet Tahoe cranks but won't start.

Hi there. If your fuel pressure is normal (35 psi or higher) then check the spark plugs and see if they are getting burn spots. If they have burn spots, then the injectors may not be working. If the fuel pressure is low, the check the fuel pressure regulator and see if it’s sticking. The fuel pump may not be coming on crating a loss of fuel pressure at the fuel rail. If there is fuel pressure, spark, and air, then the mass air flow sensor (MAF) might be malfunctioning or dirty. Remove the MAF and clean it with an electrical cleaner. Then put it back on and see if the engine starts up. If everything is working good on your vehicle and there is nothing wrong, then the ignition switch may have a fault causing the security to come on and keep the vehicle from starting. If you need further assistance with your crank but no start situation, then seek out a professional, such as one from Your Mechanic, to help you.