I only have 6.5 volts at the fuel pump. where could I be loosing voltage? The fuse is good and I replaced the relay with a new one. I have bypassed the safety shut off switch .

If the fuel pump on your 2017 Chevy Express isn't getting any voltage, but the two blue wires are getting 5 volts, there could be a few potential causes for this issue.

1. Fuel Pump Relay: The fuel pump relay could be faulty or not functioning properly. Check the relay and replace it if needed.
2. Wiring Issues: There could be a wiring problem between the relay and the fuel pump. Check for any broken wires or loose connections and repair if needed.
3. Fuel Pump Control Module: The fuel pump control module may be faulty and needs to be replaced.
4. Fuel Pump: The fuel pump itself may be faulty and needs to be replaced.

It's always best to consult with a certified mechanic to diagnose and repair this issue, as they will be able to accurately diagnose the problem based on the specific symptoms and conditions of your vehicle.

There should be battery voltage at the fuel pump. Check the battery voltage at the fuel pump relay to be sure that there is power coming from the battery. Check voltage at fuel pump fuse.

Check continuity of the wires between the relay and the pump.

Year make and model ?
You should have two hot circuits to the relay. One is for the pump and the other is for the coil of the relay. Usually power comes from the key switch.

Well you need to get out the DVOM - digital volt ohm meter an check for battery voltage at the fuel pump relay ! if you replaced it you saw the holes it plugs into in the relay / fuse box ? Put you volt meter on the 20 volt scale , hook the black lead to the battery negative or a good engine ground an take the red lead an touch - don't stick it in an spread the terminals . Two of the holes should have battery voltage ,if not check the EEC power relay ! If you find voltage at two holes change the meter to ohms , leave the black connector on a good ground an touch the red to the two holes left , one should be open or OL on the meter , this is the control side from the engine computer . the last hole should show a few ohms resistance , this is down through the wiring to an through the fuel pump to ground . You have two different wiring circuits , control an load side , load side being power to the fuel pump an control side is power an the engine computer supplying a ground energizing the relay closing the contacts in the relay sending battery voltage to the fuel pump. Test don't guess !

There is a red and white wire feeding the fuel pump relay from a 30 amp fuse. Both the shutdown relay and the fuel pump relay are grounded by the PCM, so if the fuel pump relay is grounded it should be "on" and providing a direct link from the pump to that fuse.
You should have battery voltage on that 30 amp wire before the relay and then on the dark green and black wire going to the pump.
If you don't have battery voltage coming from the 30 amp fuse, the problem could be before the fuse.
That 30 amp fuse is hot all the time, so it is powered by a fuseable link coming off the battery.

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

Ok check if there is voltage on the terminal that connects to the tank inlet usually always have problems with the negative lead so I recommend you check it .... Thanks good luck

Check the fuel pump fuse and relay. If they are both good then check the voltage at the fuel pump. If you have 12 volts for a few seconds when you turn on the ignition your pump is bad and needs replacing. If you have no voltage the fuse or relay is bad. Be sure and also replace the fuel filter.

you have a voltage drop problem probably a coroded wire if you can open wire harness and do voltage checks down the wire until you find the bad spot and repair or you can run a bypass wire