We have tried everything, spark plugs, fuel pump, inertia switch, and starter. I don't know what else to do. It cranked up fine and ran beautifully last night. we put it up on a jack to check a tire out and now this am when we went to crank it up it will not run. Any ideas? I really need help!!!!
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Re: Will turn over but not crank up
You need to tackle this logically. First of all the car has to have fuel and spark to ignite the fuel. You need to establish whether these are present or not. Then go along apporopriate route, fuel or spark.Secondly the spark has got to occur at the right time .There are simple checks you can do to find out if this happening.
To confirm sparks Remove one plug. recoonect lead , hold it in contact with the chassis and turn the engine,you should see spark jump across the plug gap. Dont hold lead with bear hands as it carries high voltage,use an insulated material to hold it in contact with chassis.
similarly you can disconnect fuel input to carbureter and turn engine to see petrol coming out.
Once these two facts are confirmed then it is timing of sparks that remains.
Hope this helps you to go in the right direction.
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Are you missing anything else?
Engine cranking, do you have spark at the plugs and fuel injector pulse? The reason I ask, if your missing all three, have to check for rpm signal, comes from crank sensor.
As far as just the fuel pump, could be the pump--voltage and or ground circuit--could be problem with inertia switch--fuse.
Any applicable trouble codes? To check codes, yourself, at the least, you need an obd2 code reader.
I don't think it is your security system, my info says your security system will disable starter motor among other components. Make sure battery has a full charge.
Hi Lee, what is your year--make--model and engine size? Because you mentioned inertia switch, makes me think you have a ford?
If it cranks good, but, won't start, have a helper crank it, while you visually check for spark at the spark plugs. If spark everywhere, use a gage and check proper fuel pressure. Also, check for fuel injector pulse, engine cranking.
Fuel inertia switch stops the fuel pump running in the case of a collision causing a broken fuel pipe which otherwise could spray a litre of petrol every few seconds and rather spoil someone's day.
Certainly a tripped inertia switch would prevent the engine from starting but I doubt it would stop the engine cranking, though I don't have up to date information on the model and there could be different safety regulations where you are.
The inertia switches are accessible and resettable so why not just reset it and try again. Your vehicle handbook will have the details.
An immobiliser stops the the engine cranking on some vehicles as well as stopping the spark and injection and often the fuel pump.
Bridging the battery positive wire to the solenoid to make the starter crank the engine won't be switching the rest of the stuff back on.
This should be in the owner's manual. I found the below on autozone.com, their repair help location:
An inertia switch is used as a safety device in the fuel system. The inertia switch is located in the cab, generally under the dashboard on the right side. It is designed to open the fuel pump power circuit in the event of a collision. The switch is reset by pushing each of 2 buttons on the switch simultaneously (some models use switches with only one reset button). The inertia switch should not be reset until the fuel system has been inspected for damage or leaks.
When the ignition switch is ON , it turns the EEC power relay ON . The EEC power relay provides power to the powertrain control module (PCM) and the control side of the fuel pump relay. Power for the fuel pump(s) is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flows through the fuel pump relay and inertia switch to the fuel pump(s). The fuel pump relay is controlled by the PCM.
When the ignition switch is turned ON , the fuel pump(s) will operate. If the ignition switch is not turned to the START position the PCM will shut the fuel pump(s) OFF after 1 second. The PCM will operate the fuel pump(s) operate the fuel pump(s) when the ignition switch is turn to START position to provide fuel while cranking.
After the engine starts, the PCM will continue to operate the fuel pump(s) unless the engine stops, drops below 120 rpm or the inertia switch is tripped.
INSTALL PRESSURE GUAGE THEN CK, VOLTAGE TO PUMP PCM TURNS ON PUMP RELAY FOR 2 SECONDS WHEN KEY CYCLED ON ,, IF NO POWER CK INERTIA SWITCH ( MAY BE TRIPPED ) IF NO POWER TO INERTIA SWITCH CK FUEL PUMP RELAY IF NO VOLTAGE AT PUMP RELAY THEN CHECK FOR SPARK AT PLUGS IF NO SPARK CK PCM POWER RELAY IT SUPPLIES VOLTAGE TO PCM THAT INTURN POWERS FUEL PUMP RELAY
Does it just crank and crank,or does it barely try to start.Check fuel pump relay under hood or for a fuse..Or turn the ignition to the run position but dont start it and have someone listen by fuel tank for the fuel pump to make the humming noise.Most of the items you have listed in the post more than likely would not make the car just suddenly not run unless fuel pump relay is bad..
If it doesnot crank at all look for starter/starter relay/starter relay fuse. Most probably wiring coming to starter is loose, try to tighten it more (push towards starter). Also I would check antiteft system (if it is provided for your car) as some BMW have immobilizers.
If it cranks no start look for spark plugs, wires, distributor cap, coolant temperature sensor, O2 sensor, fueling system (fuel pump cutoof switch, fule pump relay, fuel filter).
Please kindly let me know if you need more information, or kindly provide me with more details to assist you better