Hot weather air leak

[Lazurus]

Ok was running my saw last weekend, it was a hot day and was working around a marsh so pretty humid to, after the first running was a pig to start, done all the usual checks only thing I could see was air bubbles in the fuel feed pipe when I pressed the primer bulb. When she did fir ran perfectly at tickover and WOT, but again after stopping was a real pain to start. On return home in the evening I couldnd replicate the fault, no air leaks that I could find, certainly no fuel leak, fuel pick up in tank all ok and started first pull every time. Could that air have been something to do with the heat, or is there an underlying fault???

Its only a cheap DIY 14" saw but runs a dream, anything further I could check or would explain the bubbles in the fuel feed which stopped when it cooled off later in the day.... Hmmmmmmm curious!!

[Stubby]

3 minutes ago, Lazurus said:

Ok was running my saw last weekend, it was a hot day and was working around a marsh so pretty humid to, after the first running was a pig to start, done all the usual checks only thing I could see was air bubbles in the fuel feed pipe when I pressed the primer bulb. When she did fir ran perfectly at tickover and WOT, but again after stopping was a real pain to start. On return home in the evening I couldnd replicate the fault, no air leaks that I could find, certainly no fuel leak, fuel pick up in tank all ok and started first pull every time. Could that air have been something to do with the heat, or is there an underlying fault???

Its only a cheap DIY 14" saw but runs a dream, anything further I could check or would explain the bubbles in the fuel feed which stopped when it cooled off later in the day.... Hmmmmmmm curious!!

Sounds like vapour lock .

[Ratman]

Is it a mitox by any chance?

[Dan Maynard]

If it's a hot day and saw left in the sun then some parts of the petrol can evaporate, so the bubbles can be petrol vapour rather than air. If you have a bulb, pump it to send fresh petrol through the carb can help.

I don't have primer bulb but do find sometimes opening fuel tank to relieve pressure will help, although I did this last week and the petrol all boiled up and jumped out of the tank. Refilled with combi can from the shade and it was all good again.

[Lazurus]

Yes the tank did have a lot of pressure in it when I opened, when pumping the bulb it wouldnt send enough fresh fuel through so the vapour lock sounds the culprit, just wanted to check if I needed to strip and check the fuel lines for holes etc, but sounds like it just doesnt like the sun> My Thanks.