I’ve got a Primus no 51. I can get the tank pressurized , but it takes over 30 or 40 strokes to make things work.( A bit like a Coleman Peak 1) When I pull the pump back, I feel resistance, like a vacuum. The pump tends to solide back into the tube. Any idea what’s the cause ? Thanks in advance for an answer! Fjildman
Hi, that’s why the pump non return valve is failing and probably needs a new pip to make the seal again. The stove is loosing pressure from there into the pump tube, that’s why the pump slides back. Nicola
Look like air doesn't enter into the tube on the pull back of the pump. So then not enough air to push into the tank. Any pics?
If you have a common aged pump - it should look like the one in kerophile's link, please note how the pump plunger should be able o move on the pump rod and that the conical part of the rod acts like an air intake valve for the pump - the NRV is the outlet valve from the pump. Most problems like yours is due to a plunger mounted wrong way and fixed on the rod. If you have the early type of pump parts, the function is similar but plunger and rod have a different valve design like this one: The brass washer should be fixed to rod and hold the leather(viton works fine too) sealing washer - either bottom end of plunger or top side of rod nut need to have a passage for air when pulling the rod, as seen on the nut of this early Primus pump.
Does it leak fuel into (out of) the pump tube? That would be a classic symptom of a faulty non return valve - it allows pressure and fuel to leak back into the tube.
Hi Lennart, thank you. My knowledge of English is limitited. What do you mean by “ plunger”. The whole shaft plus leather cup?
