I just rebuilt one of my hipolito 502s and the pre heater leaks .I don't think it leaked before. If I play with it it will stop. What to do? Also it seemed to loose pressure quickly. I pumped it up to 1.5 and after 15 min or so it was at .5 . It didn't have much fuel if that matters.
Yes, it will. All other things being equal, pressure is inversely proportional to volume so if you have a low fuel level in the tank there's a large (i.e. high) volume of air above it so pressure will be low. So if you've plenty of fuel in the tank, the volume of air above it will be low, so pressure will be high...
Well, Don't stop playing ... But without playing: the small rubber stop is the seal. So check if it fits over the jet tip also after years it will get a dent. By removing and replacing this dent will not be on the same spot again and therefore leak. Easiest way is to prie (?) it out carefully and turn it over. Or replace it with a new one. The pressure part is already explained.
Well, that's true enough but for a given size of air leak/aperture, the pressure will drop slower with a lower fuel level. Ian
The OP reports a drop from 1.5 to 0.5 (bar) so it the volume of fuel/air in the tank has little to do with it - if anything a low fuel level would tend to mask the leak not accentuate it. Your statement "All other things being equal, pressure is inversely proportional to volume so if you have a low fuel level in the tank there's a large (i.e. high) volume of air above it so pressure will be low." is true in itself, but if the pressure was 1.5 bar, that's what it was, regardless of the volume.
The point is that the source of the leak needs finding and fixing and then there's no need for all this theorising!
