No volts to fuel pump - Cars & Trucks

yes. It should be 12 volts. Did you use the replacement harness you should have gotten with the pump? GM has an issue with the harness going bad at the pump that's why new pumps come with a new harness. Also check the relay.

Fuel pump relay? Fuel pump itself? Bad ground in fuel pump? Check for voltage going to the pump. If volts ok, pump is bad, if volts are not present, bad relay.

Hi Lou and Jane, Voltage should be !2 volts. Make sure of the operation of the fuel pump relay and that the relay has not become high resistance. Also check the earthing of the pump Regards John

i had the same problem, its the fuel pump relay, pull the relay, pop off the plastic top, insert a shim so that the points are always touching, the other thing it could be is the pigtail connector coming off of the fuel pump inside the tank, chronic chevy problem

It is critically important for turbocharged models that the fuel pump receive the maximum amount of voltage available from the charging and wiring system. The alternator will try to maintain about 13.5 volts into the system. Resistive losses along the current path to the pump will reduce the voltage at the pump to something less than 13.5. If there are less than 12 volts at the pump, the amount of fuel flowing may be much less than expected and perhaps enough less to create lean air-fuel mixtures under heavy boost.

The instructions below show you how to bypass the resistor and relay that the turbocharged 3S models use to reduce voltage to the pump at idle. Please read through the instructions and look at the pictures before attempting this procedure. Before I did this relay/resistor bypass I measured the voltage at the pump using the method shown on my web page 2-fuelpumpvoltage.htm. At idle the pump was receiving about 6.7 to 7.0 volts. I saw from 10.6 to 10.8 volts as boost began to build and then watched that number drop to 10.2 to 10.3 volts as boost hit 15 psi or so and RPM approached redline. After performing the relay/resistor bypass I remeasured the voltage at the fuel pump with the following results.

Cold idle: 11 volts
Warm idle: ~10.6 volts
Warm idle after radiator fan kicked in: 10.35 - 10.55 volts
Acceleration and boost: ~10.5 volts

1. Check the power going to the fuel pump. If it gets around 12 volts when the key is turned to the On position, replace the fuel pump.
2. If the fuel pump is not getting around 12 volts, check and replace the fuse for the fuel pump.
3. If the fuse is fine, replace the relay for the fuel pump.

I’m happy to help further over the phone at https://www.6ya.com/expert/jeremy_69f3cc28d95bf514

The plug you are referring to is probably the fuel tank pressure sender not the fuel pump. It would be plugged into a black sensor about 2 inches long pushed into a rubber grommet on the fuel bung. The fuel pump connector would have more that 2 wires going to it. most likely a heavy purple wire would be the power to the pump. It has to have 12 volts to it to work. The sender may have 3 wires, 5 volts, ground, and sense. the pump connector would have 12 volts, ground and 5 volts for the fuel gauge sender down in the tank.
If the 12 volts is not there, check the fuel pump relay. it is usually up on the drivers side firewall.
With the key in the on position without starting the engine, you should have 12 volts to the pump for 3 seconds then it will click off. Without cranking the engine you should be able to locate the relay by the clicking sound.
There is also the obvious, like checking the fuel pump fuse.

Pull the relay and make sure you have 12 volts there. Pin # 30 is the power to the pump. this will tell you which way you have to go to find a short or corrosion in the wires. let me know
Randy

12 volts, and thgis should be fed by a fuel pump relay.