HD5 fuel system

Yesterday, started the HD5 and it would run and then die... finally traced it to the rubber line coming up to the first fuel filter. It had gotten to just dripping for fuel flow. Also noticed the return line under the floor plate had about full turn twist in the steel line with a bunch of brass fittings ahead of it with a restricter in there just before connecting to the rubber flex hose going to the engine for the returning fuel... We replaced the main feed line rubber hose, and the final fuel filter, and cut out the twisted section of pipe on return line and slipped a section of rubber hose over the line and clamped it.
 It now does not run out of fuel, but has the ability to fog anyone down wind.

 Question - Do these engines have a restricter in the return line or are they suppose to be fully open?  and should I remove the restrictor?

   As for the fuel pressure gauge, it is not connected so do not know the PSI in the system though the gauge still reads 20PSI... Guess the gauge isn't functional anymore.  

check the air cleaner that it is not over full, has water in it or clogged. could be your fuel is old or filters still not clean. you mentioned you changed the final filter, what about the primary? they need a good flow of fuel and any remainder gets sent back to the tank. if it has not run in awhile it may just need to be run hard to clean it out or may be injectors clogging. is it just at idle or full throttle also? good luck.

Thanks for replies.
  I looked into the HD7, 10 and 14 book and see where it says fuel pressure to operate at 25-65 PSI at high idle... now it makes me believe that the twist in the steel return line was the restricter from factory, not somebody not  watching what they were doing... was to uniform.
  Book said the flow of fuel is used to cool the injectors, but still need the pressure to give the injectors adequate fuel charger.

 Dadsdozer, the air cleaner was off and cleaned, the last owner left the bowl empty and did not put a gasket/ rubber washer and wing nut back on the pre-cleaner, thus had water in the bowl.
   As for the filters, We had the primary filter out, and I would have put a new one in but parts store didn't have that filter listed in their books...
 Worse, the filter that was in there had a wire handle on it to lift it out, and was rusty... Stuck my finger in the center hole and still had daylight, the holes for the wire handle were punched into the top plate and unfiltered fuel could flow through it there... made that way from the filter factory!
  It is getting plenty of fuel now, starts and runs without wanting to stop. Had a good heavy load behind it and warmed the old crawler up to smoking off the old oil build up on the manifold. Still had smoke out of the ex pipe at all running speeds and under load, specially when over loaded. LOL...
  Wayne, on the inlet line to first filter, I cut off the old rubber hose flush with the brass fittings and then bought hose large enough to fit over the old crimped sleeves and hose clamped it.
  Next time I mess with this dozer, I will put a pressure gauge on to see what fuel psi it has.

Could have injectors leaking