BenzWorld Junior Member
Date registered: Oct 2015
Vehicle: '77 416 Cabriolet
Location: Western Wyo
Mentioned: 0 Post(s)
Quoted: 3 Post(s)
Fuel System Problem
I could really use some help! I've run out of obvious ideas. I have a '78 416 mog that has the following problem.
After priming with the handpump and bleeding at the filters and at the port on the rail, I can start up the beast. It runs fine for 10 min or so and stalls out. It sounds like it is running out of fuel. This is confirmed because the filters have been emptied of diesel - I have to pump the hand pump many times to get diesel to come out of the bleed screw of the filters.
The problem started on a cold day (well below 0F) winter day. I thought that the problem was gelled diesel. I treated the diesel and changed the filters. All seemed pretty good for a couple of more hours of run time, before the unimog stalled again. Changed filters again. Cleaned the small mesh filter just down stream of the tank. It was pretty gunked up.
Same problem persisted. Emptied and cleaned fuel tank. Put in fresh diesel. At this point, I can reliable hand pump the diesel into the filters and out the rail, start it up and have it run smoothly for about ten minutes.
To me this suggests that 1. filters (now changed twice) are fine. 2. Injectors are fine. 3. Fuel flow canít keep up with use. The fuel pump doesnít seem bad either. Iíve crank it over without starting - I can get diesel coming from the top screw of the filter.
I havenít tried to bleed the injectors, because the engine runs smoothly for 10 mins. I think that I will change the filters again. Not more than 1/2 an hour of run time has passed through these filters, but they havenít been changed since I cleaned the tank. But before do this again, I think I need more brainpower on this problem. Ideas/suggestions greatly appreciated. (Sorry about the long post.)