Thanks DJ for making my photo's magically appear.
Can anyone give some hints as to how to improve this fuel system (if at all possible). I changed the primer bulb today which was kindly posted by the guy I bought it from on Ebay.It still took about 60-70 pumps to get the fuel up and again once it starts it will start all day. This ,as I think i posted earlier, is unlike when I first primed and started it when I could come back the next day and kick it over with no priming. So to summaries it is basically loosing prime overnight. Any thoughts?? Cheers GAC
Thanks guys for your quick responses.You guys are definately on the money, The "round thing"is definately a fuel pump of the daiphragm type pumped by crancase vacuum.You can see the line comming from the crancase in the first photo. I have very carefully pulled this apart to check for damage,and apart from being fairly basic in construction, it appears ok.When I pump the primer bulb there are air bubbles in both the bulb and the fuel filter after the fuel pump.If there was an air leak wouldn't that translate to a fuel leak at some point??
Hi gac,
I think I can help you out here, I ve had a similar problem on some other equipment fitted with a tilliston diaphram pumper carb.
Please note that we are looking at the "valve diaphram" and not the vacuum diaphram in the unit.
Take the pump apart again and inspect the surface around the "flaps" of the valve diaphrams on the metal parts. These act like a non return valve and stop the unit from loosing prime.
How to fix:
Buy some 1200 wet and dry and take your parts too the local Cemetary ??? yes we are going to talk to the dead
no we just need a nice flat surface of machine ground granite!
Use the wet and dry on the granite and wet with WD 40 gently lap the sealing face in a figure 8 motion on the wet and dry (make sure the granite is free from dirt / dust first)
Check out the plate after a quick lap to see for a dull grey where the high spots are.
Keep going until you get an even dull grey around the "flap" valve areas on both parts that need lapping.
Also check that the diaphram valve material is not "burred" from the machine that made it in china. you may have to gently correct this by running you finger nail around the edge, or use an iron and put the diaphram valve between two sheets of paper over a flat hard surface; I can imagine quite a site in the cemetary now
If you get this far and all is well, nice grey flat surface and flat diaphram valve edges you have done all that can be done here.
As for the primer if it is easy to get at with the covers on, could you fit a small outboard motor primer? two squeezes on one of those should do it!
Happy lapping!!!
Oh yeah dont forget to talk to the dead while you do this you get great looks from others, just for a giggle, a word of warning though dont lap in a 666 motion!
