1988 1200 EVO sportster (in UK) No oil pressure after fitting a new oil pump etc

[Muldoonsghost]

The warning light won't go out but I have oil flow.

My 1988 4 speed has recently been rebuilt. It has done just 900 miles and I have been trying to reduce valve train noise. As a part of that I took the engine out and replaced the 32 year old pump with a brand new 2007+ pump.

https://photos.app.goo.gl/wqehSqkcfmX2pvGN9

http://sportsterpedia.com/doku.php/techtalk:evo:oil03c

But since the 'upgrade' I can't get the pressure switch to activate. Yesterday I removed filter pad to make sure the paths were clear. There are no blockages in the pipes. There is no blockage to the pressure switch. The ball in the one way valve is seating and seems to have a strong spring.

This is the flow from the pump. Looks good to me, pump is primed and outputting oil. No kinks in the pipe from the tank.

https://photos.app.goo.gl/v4o3sLEfkHpmm2Zb8

This is the flow returning from the filter.

https://photos.app.goo.gl/2CtFtS2DjxX5YMyk9

I prefilled the new filter before assembly.

If I remove the cable, the light goes out, the switch is closed. Is it a lack of oil, or maybe a faulty switch? No reason for it to suddenly fail, but...

Can anyone suggest what my next move may be?  Summer is over and I'm still fighting this machine, every day. 

[aswracing]

It's very common for the bypass valve in the filter pad to get stuck open, or for the spring to get so weak that it's effectively stuck open. When it's open like that, it dumps oil into the cam box and you have no oil pressure. Happens all the time on 4-speeds (and early '91 models as well)



Spring #22 is the culprit. Oil exits the pad and goes into the cam box through the hole sealed by o-ring 20. Just tap that area of the pad and screw a plug into it. You don't need it. The factory did away with it in mid-year 1991.

[Muldoonsghost]

Thanks for the advice, I am aware of that problem and I have tried to block the problem by putting a piece of hose above the piston in the valve, stopping it from rising up and allowing flow. There are pictures of what I did about 3/4 the way down in this album.

https://photos.app.goo.gl/wqehSqkcfmX2pvGN9

OR, if I have it wrong, have I caused it to be permanently open?

[aswracing]

If i understand you correctly, and your piece of hose holds the plunger down, then yes, you've blocked the bypass open. You want to block it closed.

[FSG]