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Re: how to test fuel pump
Use a multimeter at the plug to pump! If there is no power, check the fuses under the dash, as well as the fuse box under the hood! The lid under the hood will tell you which fuse operates the fuel system. Could just be a bad fuse, or a broken wire!
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Disconnect the wire connection to the fuel pump, turn it on and test for 12V (or whatever your car battery voltage is) at the leads coming from the battery. If 12V is present the problem is the fuel pump. Test the continuity of the pump circuit at the same time (no power on for this test). set VOM to resistance attach to both leads going to pump. If reads 0.00 continuity is OK. If no reading pump circuit is open, pump motor is bad. I have had them bad right out of the box. Good lesson to learn whenever possible, ALWAYS bench test new parts before installing.
Do you have a test light? If not, go buy a cheap $5 test light-one with a lead to clip to a ground, and with a needle type probe. Pull the fuel pump relay out of the terminals it is plugged into-you need to check if the power feed for the pump is still available at the relay. Clip the test light lead to a ground and touch the test probe to the positive battery post-to check that your ground is good- tester should light up. Now touch the probe to all of the terminals that the relay plugs into. One terminal should have power with key off. If no terminals have power, you have lost the power feed for the pump. Double check all your maxi fuses in the power distribution box. Either a maxi fuse or a fusible link will be the power feed for the fuel pump relay. If the power feed is there at the relay, try a new relay. If still no pump, a shop will probably have to check your fuel pump circuit. Did you check for power at the fuel tank while the key was held in crank? When the engine is cranking, the fuel pump wire should have power. When the key is turned to on, the fuel pump should have power for about 2 seconds, to pressurize the fuel system. Then when key is turned to crank or start, the fuel pump should stay on.
WHAT KIND OF FUEL PUMP DID YOU BUY GM OR AFTERMARKET,ALOT OF THE AFTERMARKET ONES YOU HAVE TO CUT THE ENDS OFF OF THE PLUG AND CRIMP THEIR NEW ONE ON.I GUESS THEY HAD PROBLEMS WITH THE PLUG GOING TO THE FUEL PUMP GOING BAD.OR YOU COULD HAVE A GROUND WIRE THAT CAME UNDONE.THEIR IS ONE THAT BOLTS TO THE FRAME NEAR THE FILLER NECK AREA.LOOKS LIKE A GROUND STRAP,CHECK TO MAKE SURE THAT IT IS STILL ON.GET A TEST LIGHT JUST TO MAKE SURE THAT YOU DIDNT GET A FAULTY NEW PUMP.TEST THE PLUG GOING TO THE FUEL PUMP SHOULD BE HOT WHEN YOU TURN THE KEY ON ...MAY NEED 2 PEOPLE.ALSO CHECK TO SEE IF YOU ARE HOT UNDER THE RELAY WITH YOUR TEST LIGHT.RELAY SHOULD CLICK.ALSO MAKE SURE YOU HAVE NO SECURITY ISSUES,WITH KEY OR ALARM KILLING POWER TO PUMP.GOOD LUCK
What you need to do is check you fuel pressure. Go to a local auto parts store and buy a fuel injection pressure tester. The pressure fitting is on the top of the motor its a 3/8 ish sized metal line and has a screw on fitting like a tire valve does. This line comes up from the back of the motor to the right of the distributor and goes down into the intake. Make sure to have a rag handy to catch the fuel seepage. After you connect the pressure tester turn the key on and off three times and read the gage you should have atleast 58 pounds of pressure. If you have 56 pounds it won't run because the fuel injectors are a poppit valve style and need atleast 58 pounds of pressure to operate.
buy a cheap test light/probe and use that at the fuel pump plug to check for power in that circuit.It could also be a relay thats at fault so check that for power in and power out,same test tool.There are not many wires at the pump plug but as long as only one has 12v its not a power supply problem.Does the car run at all?
fuel pump died replaced it truck ran poorly afterwards. Had a prussuer test done pump determend pump was no good. Put in another ran good for 2 days started running poorly hard to start no power. 2nd fuel pump. So i figure another bad new fuel pump wow changed it put in a third brand new fuel pump. Still will not eve start now. I had it tuned up 2 months ago new plugs rotor, cap, etc. put in a new fuel filter made sure it is on proper checked all connections for leaks. this cannot be a fuel pump problem now. no problem with the elctrical i figure i have great spark on ignition tester. I can hear the fuel pump prime when i turn the key. but when i went and checked the fuel port i had no pressure. When it is being cranked gas sews out of the test port. Also i dont if this is comon cause i used to turn my keyand go. but when i have someone turn the key and i listen at the gas tank whn the key is shut off i hear gs spraying back into the gas tank. So i am open for opinions.