oilyfinger

I've aquired an old gummed up engine, The cams and rockers were solid, I've got it cleaned up but no matter how many times I turn it over for priming, I can't get any fuel into the feed pipe. What regulator checks can I do.

tih

My Feedback: (1)

The regulator is probably gummed up, too. There are tiny little holes in there... You could open it up, and let it soak in fuel for a while. If you don't have a replacement diaphragm to fit, you should be really careful not to tear it, so you can make an attempt at starting the engine while you wait for the new diaphragm to arrive.

oilyfinger

I've had the regulator apart and washed it in methanol. The diaphragm looks good no visible perforation. I've fitted it back on with the line mark forward, it was to the rear when I got it. Does the fuel flow under or over the diaphragm? (Mounted upright)

tih

My Feedback: (1)

Just to have asked the obvious: are you certain that you've got the plumbing connected correctly? It's more complicated than a normal engine, and people tend to move the tubes around when storing an engine, to keep dirt out. The manual is here:

fz53.pdf

Useful additional information (VERY useful, in fact):

Fact Sheet: YS Engines

Now to your question about where the fuel flows: this explains the workings of the regulator valve:

http://www.gbrcaa.org/acrobatfiles/Y...%20Systems.pdf