I just installed an AEM 320 pump into my buddies 2005 silverado bucket and now I'm running into issues with my fuel return. Here's some info on the truck:

2005 CCSB 5.3
2012 LH9 intake (Gen 4 cathedral)
52lb oem injectors
AEM 320 Ethanol pump from Scoggin
Gates submersible line in tank
Gutted stock regulator out of the bucket, only has pump and level sender
Vette filter/regulator 58 psi @ rail
Fuel return down evap line
Fuel pump has been set in the cal, so it is no longer a pwm pump


The problem I'm having is that once the truck starts and I am getting a ton of fuel return to the tank. Priming is fine but once it starts and idles the fuel starts to fill the charcoal canister till it comes out the vent solenoid. So first thing I did was unplug the vent and block the large line to the charcoal canister. This worked other than that you loose venting to the tank. So I was instructed to remove the oring to the gas cap for the time being and make the cap a vented unit. Now the fuel is coming out of the filter neck under the cap. (Less than 5 gallons in tank also)

Does anyone have any solutions to this other than drilling the sending unit and running a dedicated line for the return? I know it's not the norm to go from pwm to a std return style pump, but this is a budget build for a friend.

 

Sounds odd, but I would look at the evap line and how it is plumbed into the pump module and see if there isn't some way you can either put a line on it to make sure it returns into the tank, or drill it out in some way.

 

The Evap line was the issue along with the venting of the tank. It seems that on 2004 and newer trucks the evap line runs directly to the Charcoal canister. We didn't drop the tank, rather we lifted the bed. When lifted you cannot see all the hose routing correctly.

We simply cut off the plastic evap return line at the hard line. Added 6' of fuel hose and reused a quick connector from the rear of the tank (at the vent port) this is now the fuel return.

As for venting the tank, the charcoal canister is removed along with the vent valve. All we did is take 5' of 5/8" evap hose and run it to the factory filtered evap vent cap (small black box with screen to keep bugs/ debris out)

This seemed to work great while using the Corvette reg/filter at the fuel rail. BTW we used a 2012 intake from a Colorado with 5.3, 50lb marine injectors, and AEM 320 E85 pump for this build.

Thanks for the help.