The injector pump loses prime after 8 hours

   / The injector pump loses prime after 8 hours #1  

geocash2

New member
Joined
Aug 4, 2025
Messages
2
Tractor
Northern Lights
I have a Northern Lights generator 843n with a Shibaura 3-cylinder motor. Getting the motor to start after it's been sitting for more than 8 hours requires a lot of cranking or opening the bleed screw at the fuel intake hose and priming.

1) Could this be a faulty injector pump, or should I be looking at something else, like the injectors

2) Is there a way to test the pump installed?

3) Can these pumps be rebuilt?
 
   / The injector pump loses prime after 8 hours #2  
No idea about your particular engine or injector pump, but have you confirmed no air leaks from the tank to the pump? A small pinhole or crack in a fuel line, or a filter sucking air can cause those symptoms.
 
   / The injector pump loses prime after 8 hours
  • Thread Starter
#3  
Yes, I have replaced everything from the tank dip tube to the injector pump. After priming, the motor runs flawlessly for hours.

I posted it on this forum because the Shibaura motor is standard on several tractors.
 
   / The injector pump loses prime after 8 hours #4  
I see. There are a couple of injector pump experts here on TBN that will hopefully come in with an opinion.
 
   / The injector pump loses prime after 8 hours #5  
I’m guessing you have an air leak in your fuel supply system between the pickup in the tank and the fuel injection pump.

The leak allows the fuel to drain back into the tank.
 
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