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Q: Caravan won't run when I hit the gas pedal.

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About 3 months ago van started to misfire, shaking at 40-50 mph, used to run without effort at 180 degree angle, anything less will cause engine hard knocks. Scanner read engine misfire and then fuel injector #1 circuit, same for #3 and #4. Spark plug #4 was burned, none of sparks plugs had oil residues. Replaced spark plugs, sparks plugs wires, ignition coil, TPS, Crankshaft sensor, engine and transmission mounts, fuel pump, air filter element and PCV Valve. Performed 3 test: 1) Cylinder compression (the larger difference between cylinders was -5. Passed. 2) Fuel injector test (with a stethoscope-like tool), all the injectors were opening (clicking sound) and 3) a vacuum leak test using a smoke pressure machine. No leaks were detected. After the tests I was driving home and the van did not respond to the gas pedal. It starts and run slowly until I hit the gas pedal, it chokes like if there is no fuel pressure or no air intake. HELP!

My car has 190000 miles.
My car has an automatic transmission.

Hi there. Check for fuel pressure on the fuel rail with the engine running. If the fuel pressure is at 50 psi or higher, then the fuel pump is working. If the fuel pressure is low, then the fuel pump may not be functioning properly and would need replaced as the fuel filter is on the bottom of the pump and it may be clogged. If there is no pressure, then either the fuel pressure regulator has failed or the fuel pump relay is not coming on. If the fuel pump relay is clicking on, then check the fuel pressure regulator and see if it’s sticking. If the fuel pump relay is not clicking on, then remove the relay and see if there is power to the relay base. If there is power to the relay base, then the relay needs replaced. If there is no power to the base, then check the fuse to the fuel pump. If the fuse is good, then there is a break in the wiring from the relay base to the ignition switch. If there is power past the relay, then there could be a break in the wiring between the fuel pump relay and the fuel pump. If the fuel pump is working properly and you have good pressure, then the issue would be with the throttle pedal position sensor (located on the gas pedal). You can try to resetting the sensor by the following:

  • Turn on the ignition key to the ’ON’ position
  • Step on the gas pedal to the floor slowly
  • While the gas pedal is on the floor, turn the key to the ’OFF’ position
  • After about a minute, turn the key to the ’ON’ position
  • Slowly release the gas pedal to the full rest position
  • Turn the key to the ’OFF’ position

Now you can turn on the engine and check to see if the gas pedal response is working. If the pedal responds and the engine revs up good, then the issue is with the throttle pedal position sensor. If you need further assistance with your engine not throttling properly, then seek out a professional, such as one from Your Mechanic, to help you.

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