What is your question?
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What is your question?
a mechanic took off a wire connecting to a spark plug and stuck a screw driver in it to see if there was any spark. He said there was some spark but maybe not enough. He said either the distributed cap or a fule pump may be the problem. I think he mentioned the computer also... What do you think and what else can I try??
2 Replies
did you get a compression test like i advised in your previous posting?? Roy
If the engine cranks over the battery and starter are most likely OK. Keep in mind an engine must crank over sufficiently fast enough for the engine to support combustion and run. The engine needs three things to start, fuel (gasoline), ignition (spark) and mechanical integrity (it must develop compression in each cylinder to start ie mechanical components must be in synchronization with each other. If it had run well previous to this no start condition chances are the engine is well mechanically.If the engine had run rough, driven poorly, made unusual noises, "ran hot", or switched off while driving the problem may actually be mechanical. Start with the basics and make sure the engine has strong and even compression, engine creates adaquate vacuum ect.... Had the Check Engine light been on? Check to see if the engine has "lost" spark or fuel which could be due to any one of a number of sensors having failed or the fuel pump or related components are not delivering fuel to the fuel injectors. The engine uses many sensors to report engine temperature, air flow into the engine, crankshaft and crank shaft position sensors to allow the computer in your car to make calculations controlling fuel and spark to the cylinders. It is hard to speculate without being able to hear the engine crank over and do some preliminary tests to determine the cause of your no start condition. Check for fuel pressure (you will need a fuel pressure gauge and look up the specified fuel pressure for your vehicle). Remove the fuel hose that goes to the fuel rail and get a friend to crank over the engine to see you have adequate fuel volume (you should have approximately 1 pint of gasoline in ten seconds of cranking). Off course take proper precautions as gasoline is highly flamable. Next "listen" to the fuel injector. Using a mechanic's stethoscope (or use a long screw driver placing the handle end up to your ear place the metal tip end of the screwdriver against the body of the fuel injector), get a friend to crank over the engine while you "listen" to the fuel injector listen to each injector at the same point of the injector body. You should hear "click, click, click" as the injector is electrically opened and closed by the computer. If the injector is not being triggered you will not have fuel getting into the engine's cylinders. Disconnect the electrical connector at the fuel injector with the ignition key in the "on" position, (next position after the accessory position) you should have 12 volts at one of the two wires at the injector. This true for most vehicles but you need to consult a workshop manual for your vehicle to see that this is true for your vehicle. When the engine is running the second wire at the injector gets (triggered) grounded by the computer in your vehicle many times a second controlling exactly when and how much fuel gets injected into the engine. Spark needs to be tested to see if the ignition system is able to perform correctly. No point in guessing you need proper diagnostics. There is a company that independent auto repair shops get their information from, this same information is available inexpensively for people that work on their own cars.. The information is year make and model specific, covering repair procedures, torque specifications, fluid capacities and specifications, service bulletins, component locations, wiring diagrams ect.... Alldata is very easy to navigate http://bit.ly/AllData_Repair_Manuals_Online
Does the compression test determine whether or not I need spark plugs? What should the numbers look like in the test?
mechanics lie?? sorry to hear that. I never have and never will. i still think throwing parts at it is an expensive guess. these guesses are usually wrong. I wish you good luck. Roy
Is that the test of the spark plugs?
no, it is a test of the cylinders. they need compression to start. Roy