3406E warms up looses boost ?

[Mal4shtf]

Record fuel pressures under load with a manual gauge. Should be at least 95psi but 100 or more is desired. There is a fuel return check valve in the fuel filter head on the engine. It is the only thing regulating fuel pressure in the system. It's a spring type. Spring gets weak as it heat soaks and collapses easier. They are lik 100$ it goes in the filter head upside down near by where the fuel return hose comes in from the back of the head. More than likely your problem. Woron alot of e model cats. Pm me if u need help.