Question about 1999 Pontiac Grand Prix
Disconnect the MAP sensor which when bad will stop a car from starting but will allow it to run when disconnected although it will run rough.
Sounds like very bad compression, timing belt, or fuel problem. Hearing the fuel pump in the tank doesn't mean its getting enough pressure, nor does a fuel pressure regulator (on the fuel rail on top of the engine where the fuel injectors are seated into and from there into the intake manifold (some vehicles have throttle bodies with one or two injectors for example.)
Remove the spark plugs and see if the plugs are dry and or very wet, one can clean the plugs, gap them and put a square edge on the end terminal if there or at least note the condition and colors, deposits etc,
A bad cam sensor will not stop the car from starting but a bad crank sensor will!. Changing a sensor doesnt .eliminate the more likely possibility of a bad wire to that sensor - check wires carefully when getting a bad sensor reading prior to replacement. There is a resistance value to each sensor and one could check the sensor with a meter to see the resistance values between the connection terminals within the plug.
My suggestion is to look for a broken wire or wire that has rubbed against something and bared or shorted. Possibly near the ECM (Computer) especially within the first 2 feet of the ECM on the harness.
Another bad spot is under the Power Distribution Module, this is where all the fuses and relays are, typical problems are with wires corroding under the PDM, one could carefully remove and turn this upside down to inspect it for breaks or lumps in the wire or signs of corrosion on the terminals to and from underneath.
Note: Do not turn the car over unless that spark plug is grounded or within 1/4inch of ground to spark or damage to computer may happen.
Without an OBDII code reader you are lost in todays cars (they should provide one but at 90.00 plus to have them check the codes this is big business.
If the spark plugs are dry and you are hearing the fuel pump or its up to pressure (determined with appropriate tester connected to the connector on the fuel rail once the plastic cover is removed and a rag stuffed around it to collect spills etc. and watch your eyes when messing with pressurized fuel) then the injectors or the wiring to it leading from the Electronic Control Module also called other names)
This will give you some ideas where to look and figure out the problem, do the easiest first of course.
Please send feedback when you solve your problem.
More details of what led to the problem really helps us figure out these issues.
Thanks and hope this helps.
Posted on Feb 25, 2015
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Posted on Jan 02, 2017
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