2011 Chevy express 4500. I'm installing a 2012 harness. My problem is my fuel pump/tank pressure connectors don't match up. Paid for Mitchel manual and it is no help. My problem is the yellow wire? The second picture is the new harness

Correct fuel pump? 1500,2500, 3500, 4500 probably use different pumps.

I don't see a problem except possibly the diagram is not for your vehicle.

Good Idea I will check. Thanks

I'm running into this a lot. Nobody lists the 4500 closest I can come is 3500 Anyone know the difference?

Using Rockauto to check your part #'*., I'm seeing a huge difference in the listing for the 3500 vs your 4500.
Where did you get your current pump and what is the part # on the package? Is it GM OEM? Or junk-market?

don't know if this helps. The 4500 is a Cutaway, or box truck with the front being the cab of the Express. Think short school bus. So it'* usually listed as commercial vehicle.

you can only get the 6.0 liter gas engine or the 6.0 diesel engine in the 4500.
what engine do you have?
Is the truck you're working on a van or a cutaway?
this info would help us research better. But you need a correct diagram. like Carfixer007 said.

The fuel pump is the one that came in the bus. I don't have the credit card (option sticker) so I don't know what it came with.

Shuttle bus