Cadillac Repair: 1990 cadillac deville, fuel pressure gauge, throttle position sensor

Question
I have a 1990 4.5  cadillac Deville I did everything to try and get it to start.  I know I am getting spark but, it still won't start.  Do you think it could be the timming chain?  Could you please help me on this on thanks.  

Answer
Hi Laurie, If you have spark then the timming chain should be good otherwise the distributor couldn't turn to create the spark. One way to verify that the timming chain is ok and hasn't jumped a tooth is to mark the sparkplug wires so you know how they go on the cap and then remove them and the electrical wires that go to the cap. Then remove the distributor cap and crank the engine over. When the rotor terminal points towards #1 cylinder on the cap the timing mark on the crankshaft pulley line will line up with the 0 on the timing tab. If the rotor doesn't turn then that could mean the chain is bad.

    A quick test is to remove the gas cap and listen for the fuel pump when the key is turned to light the dash lights. The pump should run for 2 seconds and then quit. Even if you hear the pump there is still a chance that the pump is weak or the filter is restricted and not allowing the right fuel pressure to allow the engine to start. You would need to get a fuel pressure gauge that screws onto the fuel rail to determine that the pressure is correct. It needs to be 40-50psi with the key on engine off.

    Then you would need to verify that the injectors are working. There is a light called a noid light that is installed into the injector harness after the injector is unplugged. It should blink when the engine is cranking. It might have a bad injector fuse below the glovebox. And there are 2 fuses.

    There is a possability that the throttle position sensor might be reading incorrectly and not allowing fuel through the injectors. Sometimes when that happens it will set a code. You can read codes by turning the key on and holding the off and warmer buttons on the climate control panel for up to 4 seconds. Then watch the fuel panel for the codes. It will start with 888 and end with 7.0 If there are any E or EE codes then that could lead to the fix especially if EE because it is something that is wrong now. To exit diagnostics just turn the key off and the next time the key is turned the dash will be back to normal.

    Some tools are available at AutoZone or O'Reilly auto parts by leaveing a deposit and when you return them you get your deposit back.

    One other thing you could try to verify that the problem is with the fuel system is to remove the air cleaner housing from the throttlebody and then open the throttle and spray a 3-4 second shot of carb spray into the throttlebody. Allow the throttle to close and then try to start the engine. If it starts and dies that means you have spark and the fuel system is the problem...if it doesn't then you might not have enough spark such that the coil is weak.  

    I hope I was of some help. Let me know if you have any more questions. Bill