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Prime on fuel tap?


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If anyone saw the conclusion to my thread on the reserve issue would have seen my tank was half full of water. As such I've drained out the carbs and a load of shite came out of them.

I was wondering how long I should leave the fuel tap on prime? When I come to rebuild it on Wednesday.

It's a vacuum fed tap, so on and reserve only work with the engine on, then prime bypasses the diaphragm and lets fuel drop straight through the tap, it's for filling the carbs up if you take them off, but I'm also aware if it's left on too long petrol can make its way into the sump. What I can't find out is how long is too long? Just changed the oil, so I would really like to not contaminate it if at all possible.

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You'll only flood the carbs that way if your float valves don't work correctly.

You should only need a few seconds on prime for the float bowls to fill up then flip it to "On" or "Res". It does depend a bit on how much fuel is in the tank so give it 5-10 seconds and crank it over. If it doesn't fire, give it another 10. :-)

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The petrol stops when the carbs are full that's what the float valves are for

Stick it on prime and get it running then turn it to one

No fuel should get to the sump

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