Engine turns over good,nice clean spark,fuel pump relay clicks although i do not hear actual pump ? should i ? vcm code for throttle pot.if the throttle pot has failed will the engine fire and idle ? is there an easy way to check for fuel delivery to fuel pressure rail\regulator ?
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I would first suspect the fuel pump. Do you hear it buzz on for a couple seconds with turning the key to ON, not start?
It should come on for 2 seconds to prime the line with pressure to the engine. Do you hear it? Stand by the gas tank and have someone cycle the key to on if you need to.
If you hear nothing from the tank, you need to investigate the fuel pump and it's circuit.
There will be a fuse for the fuel pump, it is under the hood in the power distribution box-the fuse/relay block. The power for the pump goes from that fuse to the fuel pump relay (also in that fuse/block) and when the engine computer signals that relay on, the power goes through the relay and then directly to the pump in the tank.
Try this test, if your pump doesn't work-test the FPR-to test if the relay is getting a signal from the computer: hold your finger lightly on the relay. now have a helper cycle the key again from off to on (not start). Every time the key is cycled you should feel the click of the relay energizing. If you feel it click and you checked the fuse and it is good, and you still have no pump coming on, then it is likely you need a new pump. Bang on the bottom of the tank, a couple of raps, then see if pump turns on. A failing pump can sometimes be turned on by jolting it like this, but it only works a time or two or three.
So now what? If the pump is working and putting fuel to the engine, then check for spark at a spark plug. Usually a sudden no start means the engine has lost either gas or spark.
Can you hear the pump hum or buzz when you turn the key to on? It should come on for a couple of seconds to pressurize the fuel system. If you don't hear it, check the fuel pump fuse. If fuse is good, find the fuel pump relay under the hood. Hold a finger lightly on the relay and have someone turn the key to on. You should feel it click on to power the fuel pump. If no click from the relay, you will have to diagnose the fuel pump circuit. The relay should have power from a fuse link or a maxi-fuse that may be out. The computer signals the relay to turn it on. Now if you do hear the pump, you would want next to check the ignition circuit: check for spark on one or two of the spark plug wires. The ignition is probably good if you see a blue snapping spark. If weak, intermittent, or orange colored spark, the ignition circuit would need diagnosing.
I think you are making some assumptions and may be overlooking the problem. What is the actual fuel pressure at the rail ? Are you getting a good spark at the plugs ? Do you have normal compression on all cylinders ? Is the check engine light on when you turn the key on ?
I'd have to test when problem is ongoing. When you first turn on key, no crank, you should hear the pump run for a few seconds then stop. For initial prime, the computer doesn't need rpm signal. Engine cranking, the computer needs to see rpm signal or it won't ground the fuel pump relay. W/o rpm signal, no spark at the plugs and no fuel injector pulse. I know your talking about fuel, but, when problem is ongoing, check spark and fuel injector pulse, engine cranking.
Intermittent problems are a pain, have to test when problem is ongoing.
If it cranks strong then it's probably not the battery/alternator/starter. Check the battery terminals to make sure they're clean. Cars need 3 things to start and run: fuel, spark, and compression. If it's just cranking it might be the fuel filter and/or pump. Could also be a fuel pump or PCM fuse or relay. Check your manual to find the locations of those in your fuse panel or in the fuse box under the hood. When you turn the key to on, before trying to start it, you should be able to hear the relays clicking. If you put a finger on it you should be able to feel it click (you'll need a friend for that). You should also hear the fuel pump pressurize when you turn the key to on before starting. It sounds like a humming sound that lasts about 3 seconds. If the relays don't click, that's probably you're problem. And if they do click and you can't hear the pump, then you'll probably need to replace the fuel pump and filter. If you hear the pump pressurize then you probably have electrical or spark problem. Hope that helps!
you going to have to narrow it down to see what part is defective. first check make sure you getting sparks by pulling one of the cable and use spare plug and ground it making sure you getting fire when turning engine over. 4 things need to check for fuel delivery. fuse, relay, fuel pump and crank sensor. assumed fuse and relay are good, using 12v light tester locate the fuel pump connectors and connect pos and neg terminal and have someone turn engine over and see is you getting any power to the pump, if the pump is good, crank sensor will be faulty, what crank sensor does it sense the flywheel turning sending info to the ECU then the ECU send power to the fuel pump. keep in mind, fuel pump will only turn on as long the crank sensor sense the flywheel turning.
if car wont start.make sure your battery volts are 12.5.if not charge battery.or replace it if dont hold a charge.if battery is good engine wont turn over.make sure battery cables is clean and tight if all good no start .have starter and starter solenoid check.if battery and starter is good.check for fuel .has some one turn ignition to the on position.go to rear of car listen for fuel pump noise.if your hear fuel pump check ignition system for spark.go to auto parts place buy a spark tester.if you get no spark .check .ignition fuses and ignition module.if you hear no fuel pump.replace relay or fuse.if if fuse and relay good replace fuel pump.if every thing good .your car could have crank sensor problem. or your car is in theft deterrant mode.if so have your car towed in and scanned.