P0455 GMC -

Question

Engine viberates and strong fuel smell with a code po455 engine rpm is up and down

Answer 1

P0455 Evaporative emission (EVAP) system large leak

P0455 codes would be caused by missing fuel cap, improper sealing of the fuel cap, a the fuel tank filler fill hose having a big obvious tear,and of course you can smell the raw fuel, but for this code to cause the engne to vibrate? and have the engine RPM go up and down. ?  The only wayP0455 can be the cause of the unstable RPM and engine vibration is if the charcoal canister is saturated with fuel, and this can be cause by having the fuel tank over filled.