ok drop the fuel tank and grabed my little tool that lights up with power and ground, check to see if there was power in the connectors, the black one had power to one connector, but the white one did not have any power , how do i check to see how much or if any power is going in??? i have a 2001 blazer , i have checked all the power sources like the battery , fuses and also the relay..help pls thanks guys,
daniel

 

The black, square, four pin connector is your power feed to the pump and also contains thesignal and return for the fuel level sending unit. The wires are as follows:

• Pin A - Purple - Fuel Level Sensor Signal
• Pin B - Gray - Fuel Pump Motor Feed
• Pin C - Black - Ground
• Pin D - Fuel Level Sensor Return

So you should have +12V at Pin B (gray wire). I believe the purple wire should be +5V reference for the fuel level sending unit.

The other connector is to the fuel tank pressure sensor which is used for the evaporative emission system monitoring.

 

damn it , so there is no power to the pumpmotor? because with the key foward i used the little light and nothing, i did see that 5v one because the light turn on lightly on that one, not the 12v there was no light to that one at all...powering on .

 

The pump will only run for a short period of time after key on so you have to do it quick.