Troubleshooting a friends EX120, 4bg1 engine ~4600hours. Runs strong, smooth, no smoke but it only starts with fluid. Even after going through warmup , idle comes down, wait another 30min for it to come up to full operating temp... if we shut it down it won't start again immediately after that (not even one cough, with or without glow plugs). He said the problem started suddenly. He did the following before I started troubleshooting: -changed all the fuel filters -changed lift pump -cleaned the screen in the banjo fitting at bottom of lift pump -cleaned/tested injectors I put new glow plugs, checked the valve lass (it was fine), I pulled one injector out and cranked the engine to make sure it sprays fuel: it does (maybe not enough?), made sure the fuel actuator works properly and holds the racks in the start position (~half way between min and max travel). Any ideas what it could be or what to try next?
First guess would be fuel pressure issue, or injector bleeding off.
How was this done? The symptoms you are describing is usually the fuel injectors not atomizing the fuel efficiently or weak cylinder compression.
The injectors were taken to a local company specialized in injector service. I assume they cleaned and tested them for flow and atomization pattern. They were installed with new cone washers. Injector bleed-off did seem excessive (to me) when I removed #4 injector and installed it up-side down to check if fuel is getting through it when the engine cranks. Initially I didn't connect the return line because as far as I know there should be a minimal amount of fuel being returned; However when we initially cranked it, a lot of fuel came out and went down the injector hole; I didn't want to flood that cylinder, so I installed the return line before testing again. If there is a way to figure out what's normal, I'm interested to know. Since the issue started suddenly is it possible there could be something wrong in the injection pump instead of the individual injectors?
We need TPG to weigh in on any injector pump possibilities. Can you post a pic of the injector pump, preferably with the id plate on it? Since it’s Hitachi maybe MG has info?
ok ive worked on the 270ex -5 and 330 ex -5 and now have a zaxis 160 ...i ve had problems with the copper washers at fuel lines it was losing prime ... i would start with banjo fitting that has screen in it i assume thats the one you described as bottom of lift pump ...i think the 270 had 2 screens in banjos fitting at different places ..ive had a bad lift pump that sucked air also ..hopes this helps
Next time your at the machine, pump the hand primer while someone turns the key/ cranks the engine.. If it starts, the problem is the overflow valve.. Good luck BTW.. starting position in PAST max fuel.. not between low idle and max
Thanks for all the feedback. I'll try the suggestions and get more info next time I'm at the machine. In the meantime, here's a couple videos I took previously. Engine running (started with starting fluid): Trying to start engine immediately after shutting it down (engine already warm):
I'm having sort of the same issue here on a 200 just won't start all of a sudden. Turns but no start just happened