2001 ford f250 7.3 diesel, leaking fuel. When running a/c get diesel smell inside cab. A friend mention something about a huey pump. Need help Lenny

"Heuy" as mentioned above refers to H.E.U.I. Which stands for Hydraulic electronic unit injection, using both oil pressure and electronic signal to activate injection. However, referring to odour you smell I would first look for any visible leaks under the hood from possible low pressure line such as the return line or supply to the injection pump. A leak in a high pressure line would result in poor performance and you would immediately notice missing. Not to mention an abundance of fuel. As well if a leak is present, air may also enter the system causing poor performance and so on.