- Mon May 28, 2018 8:55 pm
#77050
Simple example, put a length of 1/4" fuel hose on the end of a medium-small plastic funnel. Fill the funnel full of water with the end of the hose blocked with something, then unblock the end of the hose, suggest you do this over the sink or the garden. See how it gushes out. If what comes out of your fuel tap by comparison (with the petrol tank cap removed in the test I described earlier) is a mere dribble, then your fuel tap needs prostate surgery!
What it boils down to is this - if the petrol can come out of the tank and into the carb AT LEAST as fast as your carb jets feed want to feed it into the engine, preferably a little faster than that to give a margin, you're winning. What you have been describing is the engine using petrol faster than it can leave the tank, the two most likely reasons are a partial fuel blockage in or around the tap, or a blocked tank cap breather hole. Maybe a bit of both?
Now go back to the funnel and 1/4" hose and repeat the experiment with the main jet from your carb fitted the end of the hose. You will see how much gets through the main jet. Your tank/tap/fuel hose will need to be able to supply at least that amount.
A.
What it boils down to is this - if the petrol can come out of the tank and into the carb AT LEAST as fast as your carb jets feed want to feed it into the engine, preferably a little faster than that to give a margin, you're winning. What you have been describing is the engine using petrol faster than it can leave the tank, the two most likely reasons are a partial fuel blockage in or around the tap, or a blocked tank cap breather hole. Maybe a bit of both?
Now go back to the funnel and 1/4" hose and repeat the experiment with the main jet from your carb fitted the end of the hose. You will see how much gets through the main jet. Your tank/tap/fuel hose will need to be able to supply at least that amount.
A.
