A while back I lost all power while using my Skid Steer. I took the injection pump off to go through it and I figured I would replace the injectors as they weren't to expensive and I thought that if anything came apart in the pump it may have clogged the injectors. When I took the pump apart I found that the weight retainer rubber had fallen apart. i replaced that as well as the other seals inside, threw everything back together and installed it. I made sure my fuel pump timing marks lined up when the engine was 12 degrees BTDC. I bled the system and confirmed I was getting fuel out of each of the lines just before the injector. I started the skid steer and she fired right up but there is a bad knock coming from cylinder #4 (I think). The smoke is a little white but nothing crazy. The knock sounds like a mis-fire. If I had to guess I would say one of the cylinders isn't getting fuel so I'm thinking its a bad injector. The injectors are new out of the box and the only thing I did was take off the nuts for the stopper so I could get the return line nuts on there. I was careful to count the threads when I took the adjustment nuts off and put them back as close to the same as I possible could. I couldnt find anything on how to adjust those nuts outside of bench testing them and I dont have the resources. Do you guys think I may have screwed something up and the injectors not opening all the way? Is there a general guide for adjusting those nuts or do I need to go get them bench tested and adjusted?
Injector knock is caused by the injector leaking fuel or opening at too low a pressure, which causes the fuel to light too soon as the air heats up in the cylinder on compression. Same as preignition in a gas engine, some folks call it "spark knock" in gas motors. I don't know why you would have to do anything to the injector to install the return tees, in my experience you do have to unscrew the fitting nut, remove the rubber sleeve, slide the nut over the top of the injector, slip the sleeve over the top of the injector, work the nut up over the sleeve, and the install the tee on top and thread the nut on? YMMV. Easiest way to confirm diagnoses of injector problem is to at idle loosen each injector line at the injector (be careful not to get your hands close to the leaking fuel, injection injuries are nasty) this essentially kills one cylinder at a time, then tighten the line up and move to the next one. When you find the cylinder where the knock stop when you loosen the line, that's the troublemaker. To confirm the problem is in the injector swap it with one as far away as possible, if the problem follows the injector, there you go. Might have to take it to a fuel injection shop and get it reset. If it's not the injector, have to back up and regroup.
lantraxco, thanks for the advise I'll give that a shot
I agree with Lantraxco, since you effectively adjusted the pop off pressure on all the injectors , you need to pull them all and have them recalibrated. I have seen this happen before and the engine will never run right till get them all calibrated or replace them. The adjustment is so fine they can never be reset properly by counting threads.