Ran out of fuel pump??? Does this sound right?
Learn new stuff all the time!
Use a multi meter. To do a voltage drop you check positive to positive or negative or negative. You can only do a voltage drop test when a circuit is loaded(has current moving through it)
All a meter measures is difference in potential( buy the difference between the leads) It doesn't know or care if it's positive to negative, positive to positive, etc.
Lets say you want to test the positive from the alternator to the pump. Put one lead on the B+ on the alt and the other at the connector for the fuel pump and make a pull.
For example, when you were doing your pull the meter showed 2 volts, that means you are loosing 2 volts from the back of the alt to the pump. This can be from a bad wire internally, connection or bad ground. Also a fuel pump that is drawing excessive amperage can show a voltage drop.
Do the same thing on the ground side. Typically .50 volt or less is acceptable. There should be very little to no voltage on the ground side. Grounds get over looked a lot. You can have all the battery voltage in the world but if the ground side can't carry it back it's just as bad as having too little power.
A voltage drop will show problems in wiring/circuits that you can't find any other way. Most people us Ohm's to test a circuit. IMO the Ohm test is freakin' worthless and rarely ever use it.
All a meter measures is difference in potential( buy the difference between the leads) It doesn't know or care if it's positive to negative, positive to positive, etc.
Lets say you want to test the positive from the alternator to the pump. Put one lead on the B+ on the alt and the other at the connector for the fuel pump and make a pull.
For example, when you were doing your pull the meter showed 2 volts, that means you are loosing 2 volts from the back of the alt to the pump. This can be from a bad wire internally, connection or bad ground. Also a fuel pump that is drawing excessive amperage can show a voltage drop.
Do the same thing on the ground side. Typically .50 volt or less is acceptable. There should be very little to no voltage on the ground side. Grounds get over looked a lot. You can have all the battery voltage in the world but if the ground side can't carry it back it's just as bad as having too little power.
A voltage drop will show problems in wiring/circuits that you can't find any other way. Most people us Ohm's to test a circuit. IMO the Ohm test is freakin' worthless and rarely ever use it.
