The company I work for has about 25 bread truck in our shop, all have 4b engines. We are having a problem with one of our trucks. When it's cold engine, it runs fine, after it warms up it loses all it's power (so bad it bearly does 40 mph). We have changed the Injectors, Transfer Pump, Injection Pump. Checked timing several times and run the valves. Today we changed the turbo and no difference. The truck is a Freightliner chassis. The injection pump is the in-line and the turbo is wastegated with an intercooler.
We are at wits end with this truck.
Any help is appreciated.
Thanks
Chuck Robey

 

sounds like you need to hook up a restriction gauge to the inlet and the return fuel lines , I would also check the fuel tank and see if the vent is plugged.