The 2004 GMC Sierra-1500 runs on regular unleaded.
The 2004 GMC Canyon runs on regular unleaded.
The 2004 GMC Yukon runs on regular unleaded.
The 2004 GMC Savana runs on regular unleaded.
The 2004 GMC Yukon-XL runs on flex-fuel (unleaded/E85).
The 2004 GMC Sierra-2500HD runs on regular unleaded.
The 2004 GMC Savana-Cargo runs on regular unleaded.
In the fuel tank
The 2004 GMC Yukon has a 4-speed automatic.
The 2004 GMC Savana has a 4-speed automatic.
The 2004 GMC Canyon has a 5-speed manual.
I do not have a Z71, but my 2004 GMC does not have a fuel filter, very strange because when i go to a parts store they have one listed.
remove fuel tank.