Hi, I have a 1998 sport sohc 4.0 that has 126000 miles on it. The error code is PO 455. The read out on the reader says " PO 455, evaporative emission ctrl. sys leak detected. ( gross Leak ). I replaced the gas cap, dropped the spare tire and the plate that holds the vapor canister and the vapor valve and inspected by both smell and sight. I traced the tubing to the engine but was unable due to inspect the tubing under the battery and AV compressor. Today it warmed up to
75 and I sniffed for gas vapor in the engine compartment and at the gas cap.If you have had experience with this system and would be willing to share with me I would appreciate it. The parts are expensive, so I am looking for a back yard diagnostic process if possible. I have searched the internet and have found the ford process of injecting smoke into the system, and another troubleshooting method of bench testing the valve and canister but that required a test machine. I am getting voltage to the valve with the ignition turned on.
Thanks in advance
Everett Cotton