I am new here. I just figured out I should have been posting technical questions on this forum in lieu of on the discussion forum. I inherited an Optimus 1550/500cp from my late father. It is a mid 80s jewel and looks beautiful. I had several leaks that have been a solder repaired and have installed a rebuild kit. She will preheat and light up very very nicley. There are no leaks anywhere under good high pressure. The problem is she bleeds down from normal pressure very rapidly. From normal pressure she will bleed down and go out in less than 2 minutes. Here is my somewhat stupid question. I only put a cup of fuel in the tank to do an initial operating check. It has only ran 4-5 minutes on the cup of fuel. Will low fuel cause pressure to drop rapidly?
Hi rsumphrey I would think you are correct about the low fuel level being the issue. Try a full tank and see how she runs. If she still loses pressure empty the fuel and do a pressure test in a large bucket. Bubbles mean leaks. Let us know how you get on and some pictures would be nice too. Regards, Jeremy
Thanks Jeremy. I will try filling her up with fuel. I am an aircraft mechanic and borrowed some leak tec solution. From the shop. If there is a leak this stuff finds it. I originally had leaks all over this beauty but am pretty confident she is tight now. With it pumped up and turned off she will hold pressure for a very long time (9 hours +). I am having a problem loading pics as it says the file is too large.
No, a low fuel level will not make the pressure drop rapidly. Actually it's the other way around! A low fuel level will mean a larger air volume and thus preserve the pressure much longer, so that shouldn't be your issue. Unless you actully have so little fuel in it that the pick-up tube will end up above the surface after some minutes of running. (You might of course also have a leak somewhere higher up on the pick-up tube, making it suck air after a while which would drop the total pressure pretty fast.) If that not is the case, you clearly still have a leak somewhere. Pump it up without any fuel inside and dunk the whole thing in water.
Thanks much. Just found it. Have a small leak around the center threaded insert portion around the solder. Time to get the mini torch and solder out.
That's great news. But then again, a pressure dropping problem is seldom hard to localize. Regarding what you said about your files being too large to upload to the site, just have a look here. You can use this online resizer to tweak your pics in a fairly easy way if you don't have a photo editor of some kind installed to your computer.
