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Clayso
Clayso, Master Automobile Technician
Category: Chevy
Satisfied Customers: 880
Experience:  ASE Master Certified Automobile Technician. 30 Years Experience.
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I have 2011 Chevy Express 6 liter Vortec. The van has never

Customer Question

I have 2011 Chevy Express 6 liter Vortec. The van has never had a problem and has always run great. Then out of the blue last weekend I went out to start it, and it would crank but would not start. I thought it wasn't getting fuel, so I checked the fuse for the fuel pump and it was good. Then I checked the relay for the fuel pump and it also was good. I then proceeded to get under the van with my ear to the gas tank while having someone turn the key to the on position, listening for the pump to start loading. I heard nothing. It made zero noise. From this I decided that it was my fuel pump, so I bought a new fuel pump assembly and replaced it. I went to start the van afterward and it was still doing the exact same thing. It would crank strong but just would not start. I went to check and make sure it wasn't the crank shaft sensor, and put my spark tester on one of the plug wires and it was getting spark. I'm at a loss at this point as to what it could be. Also, I did OBD testing and it came up with no codes. I then thought maybe it was the theft deterrent system/passkey. However, the security dummy light does not come on or flash so I don't believe that this is the problem either. Could you please point me in the right direction as to what to look for next? I'm at a total loss and want to blow the van up.... It only has 50,000 miles on it and shouldn't be doing this. Why does it hate me?!
Submitted: 11 months ago.
Category: Chevy
Expert:  Clayso replied 11 months ago.

Hi There, I'm Clayso a certified master automobile technician with 30 years of automotive repair and diagnostic experience.

From your description sounds like the problem is in the Underhood Bussed Electrical Center (UBEC). With a test light verify the #24 30a GAS FUEL PUMP fuse has power during cranking and initially turning on the key. If there is no power at the fuse then obviously there will be no power on the gray wire out to the pump.

When you first turn the key on listen for the fuel pump relay to click. If the relay doesn't click remove the relay and verify battery voltage on pins 30 and 85. There should be power at all times on pin 30 and for about 2 seconds on pin 85 just after turning the key to the on position. If you have power at the relay connector you can jump pins 30 and 87 and see if the fuel pump energizes. If the fuel pump does not energize with 30 and 87 jumped let me know, I'll have to put together a diagram for the location of the gray wire from the UBEC. Also let me know the first 10 of the VIN to assure vehicle accuracy. The fuel pump relay should have numbers 30, 85, 86 & 87 stamped on the relay.

Let me know.
Thanks

BTW, I can't answer as to why the van hates you. I do know they have more reason to hate me from all of the words I've had with them over the years.

Customer: replied 11 months ago.
Okay I forgot to tell you that I had check for voltage at the fuse #30 and the 30&85 relay pins. Checked again to make sure and I had 14v at the fuse,16v on pin 30 and 14v at pin 85. I dont know if this makes a difference but I had no voltage at the fuse with the relay out...I suspect that is the way its supposed to work.
Expert:  Clayso replied 11 months ago.

The #24 fuse will not have power until the relay is energized. The link below is a circuit diagram for the fuel pump and the fuel pump relay.

Fuel Pump Relay Circuit

I'm pretty sure the problem is going to be found at the X2 connector on the B1 terminal. This is the gray wire coming out of the UBEC and going to the fuel pump. What I've seen is with the relay jumped and power through the fuse there is not enough current to power the fuel pump. I always check this circuit with a headlamp as a test light. I see you have some pretty wild voltage readings 16v and 14v. Voltmeters won't load circuits and in my opinion cause more confusion than solutions. Jump the relay and verify battery voltage at the #24 fuse and then verify battery voltage on the gray wire at the pump.

Let me know what you find.
Thanks

Expert:  Clayso replied 11 months ago.

Hi there, just checking to see if you found power to the fuel pump yet.

Let me know.

Positive ratings are greatly appreciated.

Thanks

Customer: replied 11 months ago.