hey i am having problems with my fuel pump .... i have a volt meter and i am getting 8.65 volts??? should it not be 12 volts? when i turn the key i cant hear the fuel pump come on... all my fues are good? can anyone give me some information?

 

Sounds like it's shot. Yeah it should get 12 volts, but when the car is running it should be 14.4 volts. Double check the relay then. Make sure the voltage drop isn't there.

 

Check the whole circuit for bad connections before you change the pump. You should have no more than a 25millivolt drop accross anything but the pump. If that's not the case, I would recomend replacing whatever gives you the high drop and check again.

 

FlufyTiger has a good point, if the pump is bad enough to cause such a big voltage drop, it should blow a fuse. There is a high resistance in the current path, probably caused by a bad, dirty, or corroded connection or a damaged wire.

 

No, if the pump SHOULD be causing the voltage drop. That's the ONLY thing that should cause a voltage drop that large, the fact the the drop at the pump is under 11 volts points to a faulty connector, probably before the pump. The best thing to do would be to start out checking what your voltage is from the ground out of the pump to the negative battery terminal, don't use a common ground, as it could give a false reading. If it's anything over say... .05 volts, check the integrity of the ground wire and connection to the chasis, as well as the chasis to battery wire that the pump uses. If that's not the case, you've got a bad connector or wire before the pump. As I said before, check voltage drop accross the wires and connectors by checking voltage from the begining of the wire, or the inlet of the connector to the end of the wire, or the outlet of the connector. This will give you only the voltage that is being consumed in the section of the circuit between your meter leads. a connector or wire on an automotive circuit should never consume more than 50 milivolts, and even this is excessive, so if you find anything using more than that, replace it, and it should reduce, if not eliminate the issue. Given that your pump is only consuming 8.65 volts, it likely isn't the problem, as a faulty pump would normally either consume all the voltage in the circuit, but reduce the amperage greatly, or short internally and blow a fuse.

 

To asnswer your question fairly simply... The best thing to do ( while being a textbook answer ) is to get a manual and troubleshoot via the wiring diagram. Todays vehicles have so much technology in them be it the ECU, the PCM etc that it is impossible to " generalize " with what readings the fuel pump should have. Regardless the simple trouble shooting can ultimately make you chase your tail. You can spend alot of time checking available voltage, Voltage drop etc but if you do not KNOW where the specs are, you have no buisness trying to diagnose the problem. Sorry to provide such a general answer but I have seen too many vehicles that perform off values I almost don't want to believe is true. To know exactly how the ckt works, invest in a manual, get some wiring diagrams and values and it will be absolutely amazing how easy it is to discover a faulty ground, bad connection etc. Just my two cents.