[jamester]

Oil alarm problem with my 2001 Yamaha 150HP 2 stroke.
The oil level indicator flashes most of the time even though the main tank up on the engine is full. Then some times it does not flash and shows the tank to be full as it should. When I use up all the oil in the reserve tank, the alarm goes off and the engine goes to low speed just as it is supposed to. This happens whether the indicator is flashing or not. If the indicator is flashing, I must then use the switch on the engine to fill up the reserve tank. Some times I can fix the flashing low oil level signal by simply turning off the engine and restarting it. This does not always work however. The flashing indicator is there most of the time but fixes itself once in a while. We had the level sensor within the main tank changed and this did not help. Any suggestions on how to correct this problem? Has been happening for a number of years with no solution. Bad electrical connection in a connector??? Defective engine computer that fails intermittently?? HELP!!!!

[seahorse5]

Originally Posted by jamester

We had the level sensor within the main tank changed and this did not help.

The sensor and wiring in the remote tank is what controls the red warning light and signals the oil controller circuit so the pump will run and fill the main tank.

[rodbolt]

not quite.
while we are at it lets review terminology.
the engine tank has a 3 position switch. float up and sw1 is on and commands a remote tank pump off,float at middle position sw1 is off and sw2 is on commanding remote tank pump on. however on 2.6l v6 motors from 1990 to 95 the trim sender must be working or all pump commands are ignored.
with the engine tank all the way down sw3 is on and commands RPM reduction,audible tone set and a solid red indicate.
now to the switch in the remote tank, its an odd one as its about the only circuit on a yamaha that an open switch,or broken wire, will cause an indicate.
as long as SWB is closed you get a green indicate on the guage,this tells the oil control module the remote tank level is sufficient for oil transfer, when SWB opens the yellow indicate is lit and automatic oil transfer is inhibited but there is enough oil in the remote tank for 2 manual transfers.
now to make the lamps flash normally requires a low engine tank level coupled with SWB in the on position.
now the oil control module sees a problem that should not occur during normal operation, all alarms and RPM reductions still function but the indicators flash instead of solid illumination.you could have a faulty trim sender,a faulty SW1 switch at the engine tank,a clogged filter at the remote or a pinched oil transfer line or a corroded wire somewhere.
so remember SW1,SW2 and SW3 are engine tank switches for pump off,pump on and alarm. the remote tank is SWB and controls green lamp,yellow lamp and inhibit transfer functions.
NO other alarm indicate other than yellow and green are controled by SWB.