mercury 150hp black max oil injection warning

[aquamal]

Hi guys this problem is driving me nuts...<br /><br />I have a Mercury Brown band (87ish i think horrible brown band has been removed) black max s/n 6607965 with oil injection, got her outta storage this year and run her up. Oil injection buzzer (intermittant beep) went off when running. Switched her over to premix 50:1 (for safety) disconnected the various connectors and found it is coming from the flow sensor on the pump (as opposed to float in header), noticed on closer inspection the see through feeder tubes had started to perish, replaced these, filled inboard and header oil reserve tanks, bled oil through to remove air bubbles using bleed screw on pump, did this every conceivable way - no visible air locks or bubbles and i still get the damn buzzer going off.<br /><br />So thought maybe its the sensor or warning module, pulled the sensor and started engine - no buzzer, put the sensor back in the mounting and buzzer sounds - so it seems to be working?<br /><br />Asked merc dealer technicians and they disagree, one says it is definately an air lock in the pump - solution run engine on premix with buzzer disconnected and should clear (doesnt clear but i havent water tested it yet), other says that the sensor will not detect air locks but detects the shaft pumping???? Confusion Arghhhh!!!!!<br /><br />Other info - oil seems to be pumping fine, i have checked the pressurisation in the system and that seems fine.<br /><br />If it is an air lock is there a way to get it to clear - if not what is it???? Dont really want to convert engine to premix as the system has always worked well till now, and oil seems to be pumping fine just seems the sensor is picking up something wrong.<br /><br />Many thanks in advance

 

[dingbat]

Re: mercury 150hp black max oil injection warning

The sensor is actually looking at the rotation of the shaft so air bubbles have nothing to do with it. Get a manual and run the test to determine if the shaft sensor has gone bad. If the sensor isn’t bad it could be the warning module itself

 

[gashead1974]

Re: mercury 150hp black max oil injection warning

Sounds like the module to me. I had the exact same problem last week. Its a process of elimination. Have you checked to make sure your float is not stuck. If its ok un do the two wires from the header and try again. If it still bleeps and you say it is still pumping oil then it probably is the module itself. The easy way to tell if it the shaft is to take the oil pump of, you will see a slotted head, get some one to start it up and hold you finger lightly on the slotted section. If it is spinning while the engine is running then its not that. If that the case it all points to the module.

 

[outboard tech]

Re: mercury 150hp black max oil injection warning

Are you aware that an overheat will also sound the alarm buzzer? If the module is functioning correctly it should sound as a solid "buzz". Also an ignition failure on the switchbox at the clyinder the module is tied to (#3 or 4 I think)will also cause the alarm--trace the green wire from the module to the swichbox--move it to a different cylinder to check.

 

[wilde1j]

Re: mercury 150hp black max oil injection warning

I would guess the crankshaft drive gear (made of black plastic) is probably failing and the rotational sensor is not seeing the right oil pump rpm's. Pull the pump (no need to disconnect the oil lines) and pull the driven shaft. If it has black shards on it, the drive gear is crapping out. The fixes are a) premix, b) replace the gear [very expensive], or c) install an aftermarket electronic oiling system. A Merc OEM shop manual is very helpful in trouble shooting all of the oil related possibilities.

 

[LubeDude]

Re: mercury 150hp black max oil injection warning

Or the tank under the cowling isnt completly purged of ALL air. Loosten the cap untill oil starts to flow out around it and then tighten it. (Engine must be idling to do this).

 

[aquamal]

Re: mercury 150hp black max oil injection warning

Ok guys here is the scoop, i fixed the problem...<br /><br />Demystifying the sensors...<br /><br />I purchased a workshop manual from the states and read what they have to say about it, i knew there were only 2 sensors working the warning buzzer<br /><br />1) The float under the cap of the header tank which determines if the header is full or not.<br /><br />2) The motion sensor on the pump which determines whether the shaft is turning - this is the one i was unsure of and had conflicting reports about - dingbat is right it has nothing to do with air bubbles at all.<br /><br />i had diconnected each senor in turn and determined that it was the motion sensor that was setting off the alarm (intermittant ie. BUZZ BUZZ BUZZ as opposed to overheat BUZZZZZZZZZ).<br /><br />confusing was that the alarm was fine until i changed the perished (see through) inpection tubes (in and out of the oil pump), and bled the system of air - then the alarm started going off?<br /><br />after bleeding the system, pressuring it with air to check there were no leaks and to ensure that the oil flow was free with no blockages, i was left witht he fact that it had to be the sensor or the module, even though when i removed the sensor from the pump and started the engine the alarm didnt go off, and then when i put the sensor back in the housing (engine still running) the alarm did go off - would appear the sensor and module was detecting a change in state?<br /><br />new sensor is £80 new module is £280 - ouch, i read the manual it says you need a voltmeter and start sticking probes into the wires of the sensor in order to check it and check voltages coming back, i thought this is beyond me, maybe i can borrow an old sensor or module from someone else to help test it.<br /><br />i phoned all my local dealers - noone had a module, 1 guy had a sensor i arranged to borrow it he said he had never known a sensor to go wrong before although the modules went wrong quite often, i put it on the motor and the alarm stopped - bad sensor!!!<br /><br />i am still left with the question why did the sensor still register 2 states alarm when in the housing and not when out - the technician suggested that the sensor was kinda working but sending the wrong voltage and the module was sounding the alarm in reverse, but he said it was so rare that it was only a guess...<br /><br />Problem solved and thanks to everyone who responded esp dingbat who actually nailed the problem...