Did you check for spark?
From your original post, it sounds like the Circuit Opening Relay was tested and it is working. Other manufacturers call that the fuel pump relay. If your mechanic suggested that, it is the first thing you should have tried. Normally we do not approve of throwing random parts at a problem, but in this case finding a good used one from a salvage yard to "try" is much less expensive than an hour of diagnostic time. If it solves the problem, we are all happy. If it does not, you are not out very much.
The fuel pump will run for only one second when you turn on the ignition switch to insure fuel pressure is up for starting, then it turns off again. It will get turned on by the Engine Computer when it sees engine rotation, (cranking or running), and it knows that by the presence of signal pulses from the crankshaft position sensor and the camshaft position sensor. Those sensors also are used for injector timing and spark timing. If either sensor fails you wont have injector pulses, fuel pump, or spark. That is why you need to check for spark. About three percent of crank / no-starts are caused by a failure in the fuel supply system, where you are spending all your time. About two percent are caused by a failure in the ignition system. Close to ninety five percent of no-starts are caused by those sensors resulting in no spark and no injector pulses or fuel pump. To add to the insult, those sensors often fail by becoming heat-sensitive. One will fail after the engine has been running and commonly after a hot engine has been off for a few minutes. That eliminates natural air flow that helps to keep them cool. They will work again after they cool down, typically after an hour or so.
Saturday, September 17th, 2016 AT 12:26 AM