After a fuel pump failure I have been attempting to get my XZ running correctly again.
The symptom is flooding in the front carb. Nice.
I tried a Virago fuel pump as an alternative. It simply produces too much pressure. The floats don't seem able to overcome the pressure. I may insert a regulator later.
Going back to the OEM pump after repair it seems the front carb is flooding. I am thinking it is coming from the vacuum valve on the fuel pump.
After draining the carb bowl I attached a small tank to again check the fuel level. 20mm below the gasket face. Spot on.
Start the engine and within a short time the overflow starts dumping fuel.
It must be coming from the pump.
Yep. Perforated diaphragm. >:(
This part is less than a year old.
I was looking for a source for diaphragm material. It is interesting to me that when I search for DIY materials suppliers in Oz always appear near the top of the list.
Maybe its time to move to Oz.
You know when Aussies talk about diaphragms they mean the other sort that the wifey uses. Sex mad those Aussies
Hard to believe the Virago is any higher pressure - the valves look identical to XZ550 and most bikes of the era have pumps only mildly stronger than gravity. Are you sure your valves and o-rings are good (of course you are!). There's probably something else going on though. I guess you'll find out after you get a new diaphragm.
Search ebay for "NOS YAMAHA KY-0472F KEYSTER FUEL PUMP REBUILD KIT XZ550"
There's one on there now. $26
Keyster don't list XZ550 any more so get it while you can
Thanks PoD.
The main diaphragms are OK but the kit may be worth acquiring. I have been looking into some films as possible replacements.
It is the bypass valve (looks like an accelerator pump diaphragm) that failed. I made a (temporary) replacement from 1/32" nitrile. It will do well enough for testing.
I acquired some diaphragm material when I rebuilt the petcock on my '83. I have searched my records and cannot find the company that I bought from. It was a gasket company that the material company sent me to located in the upper mid-west, if my memory is good.
I would do a go kart fuel pump.
https://www.ebay.com/itm/353433251027?epid=1239860263&hash=item524a436cd3:g:wTEAAOSwrh9gXeA0
a couple of members have also used an electric pump.
or if you want to stay on brand.
yamaha fuel pump.
https://www.ebay.com/itm/133936850215?hash=item1f2f422527:g:TeMAAOSwUqthlDq5