MD22 Fuel flow Problems

I have been working on a MD22 engine which at first sight appears to have poor fuel flow problems, the symptoms are that the engine will not settle at a constant speed if the revs are raised, However it will tick over, also it wont go over about 1500 rpm. Also it smells kind of like a barbeque (don't know what that points to)

I have traced the fuel from inside the tank, all the way to the injectors and there are no signs of any obstructions, the tank has been drained and cleaned recently and the filters are new, the primary lift pump is giving good pressure

I'm stumped as I'm used to working with petrol engines so any suggestions will be much appreciated

Thanks

Jeremy

Check the return line. A blockage or air can cause problems. Sometime it is helpful to place a section of clear tubing in the return line to check for bubbles.