Crank But No Start Without Boost
My beloved Suburban refuses to start unless she gets a boost. Once that initial boost is given, she runs fine. And she'll start on her own again...and again...and again - unless left to sit for several hours (i.e. overnight).
The Bus (the nickname affectionately given to my Suburban) is equipped with a new Optima Yellow-Top deep-cycle battery. The alternator is fairly young at about 1.5 to 2 years old. I just replaced my spark plugs and wires, yesterday. The dashboard voltmeter reads 12-volts with the key in the ON position. I figured that ruled out those three sources of trouble.
I measured the resistances of the primary and secondary windings of the ignition coil; the secondary coil read 5.85K, rock-steady; however, the primary coil read from 0.1 to 0.8 ohms in succession. The primary coil reading would start at some random point in the aforementioned range and climb to its' peak of 0.8 and fall to 0.1, repeating the process ad-nauseum. There is a consistent variance in the resistance reading I am receiving from the primary winding. I'm thinking a voltage is being built and stored by the primary coil and released upon reaching the bias-point established by the winding's insulation. I could be wrong, though.
Ultimately, I am an amateur at fixing my own vehicle; please forgive any errors, mistakes or misconceptions I have. Attribute them to naiveté. I am wondering if anyone reading this would be gracious enough to share some knowledge with me and tell me whether or not I need to replace the ignition coil. Or the ICM, or the distributor cap or the distributor rotor or anything in the electrical path of ignition that is keeping my baby from starting on her own.
Well your ignition is not the problem. The vehicle will start. You have a charging problem going on. Sounds like you have a digital multi meter, so first check the battery voltage. A fully charged battery should show 12.5 to 12.7 DCV. Then get the bus started and then check the voltage at the battery again. It should read 13.8 very minimum, to 14.7 DCV. This would indicate that the alternator is working or not. You battery may be just run down and need to be charged.
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