Originally posted by JLEHighland:<br /><br /> 1990 Mercury 175 OB, Model No. 1175422GD / SN 0C139827 (estimate 1100 hours, all mine)<br /><br />Beeping from the oil mix warning module has been an intermittent problem for several years. This is the beep, beep beep signal, not the solid horn sound that would be triggered by the heat sensor on the powerhead. Here is some history:<br /><br />· Oil injection pump was replaced by mechanic – did not help.<br />· New batteries – no help.<br />· Cleaned the strainer in the remote oil tank to improve oil flow to the on-board tank – this helped but did not completely solve the problem.<br />· Cap on the on-board tank is new, tight and the float switch is working properly; oil level in the tank is good.<br />· In the past, the beeping would come and go during some outings; I would rev the engine in neutral or stop and re-start the engine to make it stop. On a recent trip, nothing would make it stop. All systems checked out OK, so I added oil to the fuel tank to create a 75:1 mixture as insurance, then disconnected the power lead to the warning module to stop the noise and continued operating for the day.<br />· The bearing assembly for the drive gear to the oil mix pump was recalled and redesigned at some point; this is the part that houses the magnet that is picked up by the rotational sensor; replacing this part did not solve the problem.<br /><br />Adding the extra oil to the fuel ended up fouling the plugs and I discovered that by merely cleaning the #4 plug I could get the beeping to stop! At least until the plug re-fouled. It turns out the primary voltage to the #4 coil also provides the warning module with rotational data. I suppose the fouled plug provides a ground to the ignition circuit causing a change in the input voltage to the warning module, which then sets it off.<br /><br />I’m pretty sure that replacing the plugs will help a lot, but I have to believe this is not the root problem. What is the most likely problem and how can I test for it? A weak coil? Could I move the module wire to another coil as a test? And what caused the beeping prior to the plug fouling? Any other thoughts? I’m OK with a VOA meter, but that’s about it.<br /><br />Thanks a bunch in advance,<br /><br />Jim
