Fuel Pump


I recently put on a new fuel pump and adjusted the valves . I can only get fuel so far up th line and then it stops. I can blow air through it to get it the rest of the way. But once there it won’t go to the carb. What could be the issue ?


air leak in one or more hoses. vapor lock (air bubble stopping the fuel) ? faulty pump or the float needle is stuck in the carb. take off the hose from the carb and see if it can to pump more . you can blow through the tank from the vent to push fuel through the pump. if it can pump out fuel on the inlet end of the carb hose your needle is stuck and you need to take off the float bowl and clean so the needle valve moves freely.
You have an air leak most likely. Happened on my motor when using cheap fuel line. Threw nice stuff on there and it pumped fuel to the carb with 2 or 3 pulls.
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Did you drill and tap a place for it to vent from? Did you use any sort of sealant around the cover? Could also be a bad fuel pump. Other day at the races my friend's fuel pump wouldn't pump fuel when they went up for the feature but it worked fine in the heat and they started it up right before the feature but the fuel pump went out on the grid.


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Fuel pump inlet and outlet nipples are part of the same plate in the pump. Vacuum/pulse source goes onto the nipple on the other plate.
Change one part at a time.
First, clean the carb and replace the inlet needle.
Next replace the fuel pump -- yes, I've seen new pump not work correctly.
Next check the rest of your plumbing from tank back -- tank is venting, fuel valve working correctly, no obstructions or restrictions in the fuel line, fuel filter not plugged, etc.

Sometimes dry fuel lines and fresh engines just need primed with fuel to get them working. Once fuel has filled the carb bowl, you should be good to go. Small air bubbles in the fuel line will be of no concern and are quite common.

🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
Carlson Motorsports on Facebook
32 years of service to the karting industry ~ 1Cor 9:24
Linden, IN