Fresh rebuild engine. Plenty of flow from return line. Just no pressure at sending unit. Did some checking of a few things. Apparently there is a rubber gasket between the oil pump body and the sending unit nipple. Every diagram I can find shows NO GASKET In the location. Apparently installed at some point prior to me owning the bike. . I believe it may be blocking the metered orifice in the nipple? So NO GASKET Or Special gasket?????

 

What year bike?

Maybe post up some pictures for us?

John

 

If you pull the wires off, does the light come on? I kinda though it was wired failsafe, but I can't remember.

 

Generally
The oil pressure signal lamp switch is a pressure-actuated
diaphragm-type switch. When oil is not circulating through the
system or when oil pressure is abnormally low, spring tension
holds the switch contacts closed, thereby completing the signal
lamp circuit and causing the indicator lamp to illuminate.

 

Does it alarm on a 1 or 0, normally open or normally closed contact? Will it alarm if you pull the wire off, or if wire breaks? I though it did, but I cannot remember.

 

automotive switch?
the hd specific ones are lower pressure
test it w/5-10 lb air

 

The bike is a 1976 XLH . Circuit is normally closed,not running, oil pressure opens the circuit and turns the light off. Normally in operation, the light is on , when started and running opens the circuit to turn the light off. I did check the wire by taking it off and the light then went off. That's why I suspected a bad or stuck switch. The bike had previously, before the restoration, been sitting for 10 plus years. Engine has been professionally rebuilt by a competent friend of mine. There is plenty of flow returning back to oil tank. I took the cap off to verify that . My best guess is either the " gasket " doesn't belong in there or the wire it self may be shorted to ground? Every diagram, FSM shows no gasket in that position. I assume a property machined surface would seal that connection? Or the orifice in the nipple is clogged? It is currently back on the bike as is to prevent the oil from draining out. I will need to take it apart to again to post a picture.

 

it's 47 years old no alarm or any check engine lights. Normally closed, grounded at sending unit . Open circuit when oil pressure is present. Bike qas sitting for a long time and sometimes the pressure sensors stick. That's why I suspected a bad sender? The only reason I found the gasket ,was the two parts were stuck together and the nipple came off with the sensor. I had the separate them after removing them as there is very little room to ork with between the exhaust and frame.

 

Are we talking idle or say 3000 rpm? The old Sportster had a pressure restriction spring loaded valve that lifts above idle just so it would not pop light on at idle.

 

light stays on regardless or rpm . Idle rpm is in the 900-1000 range. I have run it up as high as I dared, no effect on light.