petter/lister PH1

Hi , I am new to this forum , I have recently bought myself a non running petter PH1 stationary engine which came off a small dumper truck , So far i've fitted a new exhaust and air filter , ive rebuilt the injector and bleeded the fuel system and im getting the clicking noise from the injector and getting a good spary from the nozzel , the engine is free and turning over no problem with the decompression lever in its on position which allows me to crank the engine upto speed , when i move the decompression lever to the off postion the engine compression becomes to high to keep turning the engine by hand and the engine trys to backfire and run backwards , when the engine backfires i get a small puff of smoke from the inlet manifold , can anyone give me some advice on what im doing wrong of what could be wrong with the engine . chris

Hi Chris and very warm welcome to the forum.   Diesels are not my area of expertise but I am sure  you will plenty of advice and help from others.

If the injection pump has not been, removed or altered in anyway; the injection timing should be ok.
I'm not familiar with that engine, but if you could find an instruction manual for it; it should tell you how to check the spill timing.
At least you know it is injecting fuel in there. The smoke from the inlet will be vaporised fuel.
You may just need to crank it faster before closing the decompression lever.