Oil alarm/hard start Merc 150HP carb.

[mikeplos]

I have a 99' Merc 150hp. I have been having issues with starting cold and hot. I have to advance the throttle to near w/o to get the motor to start. Once started it will idle rough and the oil alarm would come on. I advance the throttle and the alarm goes away and the motor surges into higher rpm, however it doesn't surge once running at higher rpm's. Once running for a while, the idle improves, but the alarm for oil returns. If the alarm module went bad would it cause this problem. I got to troubleshooting the alarm and now my motor won't start at all. I used an external tank and it still wouldn't start. I'm thinking i have two problems now. can anyone help!!

 

[CharlieB]

Re: Oil alarm/hard start Merc 150HP carb.

The oil alarm module compares an ignition signal from one of the coils to the rotation sensor on the oil pump, any difference between the two and the alarm sounds.

With intermittent rough running AND an intermittent oil alarm the first place to start is to remove the spark plugs, attach spark testers and check each cylinder coil for proper spark. You may be developing an ignition problem that causes the oil alarm.

A remote starter button is a very helpful tool.

Repeat the spark test at various open throttle settings, a broken wire in the trigger may work until the throttle moves and the wire bends/opens.

 

[j_martin]

Re: Oil alarm/hard start Merc 150HP carb.

If the oiling has been failing, you may have done major mechanical damage to the engine. Low compression makes em hard to start.

Do not run it unless you mix oil in the gas at 50:1 per your owner's manual.

Check compression, to see if you've done damage.

Then proceed to logically troubleshoot the problem. A manufacturer's maintainance manual is gold at this point.

hope it helps
John