Hi everyone, this is my first post so apologies if it is slightly unconventional. I have a 1985 BJ60 that has had a rough life. When it's cold out (sub 10 degrees C) and the truck has been sitting for a while (10 hours) it does something very peculiar on startup. After cycling the glow plugs once, I hit the key and it fires right up and runs on all four for about 3-5 seconds. Then it will start misfiring and shaking, coughing out a huge cloud of white smoke for about 10 seconds. Then it clears up and runs fine. I highly suspect air is getting into the system somewhere, but I'm having a lot of trouble finding out where.
The first thing I did is replace the primer pump with the bosch version. Then I replaced the rubber section of the fuel return line from the injectors down to the pump. I also replaced the main rubber fuel line with a section of clear line where it jumps from the wheel well to the in-line pump in the hopes of seeing air. To my surprise, a bubble did form in that clear section of line. What's even more confusing is this bubble in the main fuel line seems to have no correlation to the starting issue. I can purge that bubble out of the system with the primer pump, and yet the next day I still get the startup issue, which means air must be getting trapped somewhere else. The bubble also seems to have no effect on the performance of the engine. The engine doesn't pull enough fuel to move the bubble, so it just kind of sits there at the high point. It grows and shrinks a bit, and can get as large as 4-5cm long! I have no idea how the engine can pull fuel through that but I can honestly say I never noticed any kind of power loss while driving.
I'm thinking since the engine starts running rough only a few seconds after startup, air must be getting trapped somewhere very close to the injection pump. Maybe the top of the filter? Maybe inside the injection pump or in the injection lines? There are no visible leaks.
Any advice would be appreciated, thank you.
The first thing I did is replace the primer pump with the bosch version. Then I replaced the rubber section of the fuel return line from the injectors down to the pump. I also replaced the main rubber fuel line with a section of clear line where it jumps from the wheel well to the in-line pump in the hopes of seeing air. To my surprise, a bubble did form in that clear section of line. What's even more confusing is this bubble in the main fuel line seems to have no correlation to the starting issue. I can purge that bubble out of the system with the primer pump, and yet the next day I still get the startup issue, which means air must be getting trapped somewhere else. The bubble also seems to have no effect on the performance of the engine. The engine doesn't pull enough fuel to move the bubble, so it just kind of sits there at the high point. It grows and shrinks a bit, and can get as large as 4-5cm long! I have no idea how the engine can pull fuel through that but I can honestly say I never noticed any kind of power loss while driving.
I'm thinking since the engine starts running rough only a few seconds after startup, air must be getting trapped somewhere very close to the injection pump. Maybe the top of the filter? Maybe inside the injection pump or in the injection lines? There are no visible leaks.
Any advice would be appreciated, thank you.
