peakbagger
Well-known member
- 734
- 360
- 63
- Location
- northern nh
I did some searching on the forum for a thread which include the word "starting" and all I find is my questions from 2018 and some replies. It used to be major battle to start mine after it had sat over the winter for 4 or 5 months. A few years ago, the local Unimog expert heard my issues and suggested that my injectors and injection pump were leaking down over the winter. I never had issue during "summer season (from late April to October). So, the next spring I tried his suggestion of pumping the primer pump (new style Bosch) numerous times until the pressure relief on the pump opened up. It was successful that year and subsequent years. I normally take the hood off, but I did it from the wheel well today. When I first start pumping, i dont feel a lot of resistance in the pump but it eventually builds up after 30 or 40 pumps. I eventually feel a slow increase in pressure and just when I am ready to stop, I hear a distinct "weeze" of a small relief valve opening from the injection pump. It is not loud, but I have heard it every year I have tried this method. I counted the number of pumps I did today and it was in the 55 to 60 pump range.
I hopped in the cab, turned the key and it started right off but then lost power (but still ran) for about 10 seconds and then idled right up.
I think this is one of those not documented or poorly documented issues in the tech manual. The manual does talk about using the primer pump to get fuel flowing to the final filter cartridges until no bubbles are seen but in the case of dry injection pump that is not good enough. The injection pump body is flooded with fuel and there is fuel all the way to injector tips normally so cranking it over and over or spraying large amounts of ether in the engine really does not do the trick. So next time when the SEE has sat for months or was run out of fuel its worth trying this pumping trick. BTW, it does not hurt anything, the relief is routed back to the fuel tank as long as the iine is not pinched or broken.
My 1300 with the newer OM 366 engine with far more miles, does not have this issue. It started up first crank today.
I hopped in the cab, turned the key and it started right off but then lost power (but still ran) for about 10 seconds and then idled right up.
I think this is one of those not documented or poorly documented issues in the tech manual. The manual does talk about using the primer pump to get fuel flowing to the final filter cartridges until no bubbles are seen but in the case of dry injection pump that is not good enough. The injection pump body is flooded with fuel and there is fuel all the way to injector tips normally so cranking it over and over or spraying large amounts of ether in the engine really does not do the trick. So next time when the SEE has sat for months or was run out of fuel its worth trying this pumping trick. BTW, it does not hurt anything, the relief is routed back to the fuel tank as long as the iine is not pinched or broken.
My 1300 with the newer OM 366 engine with far more miles, does not have this issue. It started up first crank today.
Last edited:
