So im wondering if anyone has had any issues like this, cause im at a loss.... So we went to start this old girl today after an overhaul (new pistons/liners, totally overhauled head etc) and at first it smoked up the shop like the engine was getting fuel and now it has basically quit smoking.  When i crack the injectors all seem normal except #6 which is hissing and spraying air.  When i tighten that injector it then proceeds to push pressure back into the fuel tank.  Ill try to attach a couple vids and pics.  I should add that this cat has been converted to direct start, and it started and drove into the shop and we havnt screwed with the injection pump until now.  we have replaced the plunger twice on it and it keeps doing it.  Any one ever runSo im wondering if anyone has had any issues like this, cause im at a loss.... So we went to start this old girl today after an overhaul (new pistons/liners, totally overhauled head etc) and at first it smoked up the shop like the engine was getting fuel and now it has basically quit smoking.  When i crack the injectors all seem normal except #6 which is hissing and spraying air.  When i tighten that injector it then proceeds to push pressure back into the fuel tank.  Ill try to attach a couple vids and pics.  I should add that this cat has been converted to direct start, and it started and drove into the shop and we havnt screwed with the injection pump until now.  we have replaced the plunger twice on it and it keeps doing it.  Any one ever run into something similar ?

 

       

Might have a bad injector capsule [nozzle], cylinder compression is pushing back thru nozzle, line and pump.

did you do any work on the injectors when you did the heads?.
a bad injector seems likely

Hi Team,
compression pushing back into injection pump fuel gallery is a sign of a failed injector nozzle--sticky valve or crud on the valve and or seat.
A blob of crud on the injector nozzles tapered seat down in the pre-chamber can distort the injector nozzle too as well as over tensioning.
Sounds like your nozzle is really jammed open as usually the leaking injector leaks back a small amount of compression/combustion gasses into the fuel injection pumps fuel gallery and causes an intermittent miss that disappears when the faulty injector nozzles fuel line is cracked thus identifying the faulty nozzle.
Cheers,
Eddie B.

all of the actual nozzles that are in the head are brand new, but i guess i could swap two and see if the issue moves to a different position. thanks for the input guys ill give it a shot.

Hi Team,
at The Dealer it was not unknown for an odd few new capsule nozzles to become stuck open after being fitted to an engine.

Parts Dept. used to bring them down to the Fuel Pump Room for testing before issuing a warranty replacement.
More often than not a quick jabbing lever handle pump or two in the hand operated injector tester got them working.

Somewhere I seem to recall reading a Cat publication article on this procedure/issue.
If I find it I will post it up.

EDIT,
OK I found the article on capsule cleaning. I never saw one of these cleaner rigs but we did a similar process in our hand test rig as described above --I cannot recall the ratio of successes to failures but this may get the nozzle working for you, or simply take it back to where you purchased it and ask for a replacement--they may do the above test procedure first though.
Service Magazine article was issued in the issue of March 10 1955, page 2.
Cheers,
Eddie B.

a similar method is used to clear grease nipples. its amazing what can be done by the judicious application of that scientific instrument the knockometer.