Constant Alarm issue on Starboard Engine

[WWG1WGAFAFO]

We purchased a 1992 Sea Ray 400 EC this May and we have had none stop issues with the Starboard engine. The engine is a 7.4L MIE (LH) Gen V GM 454. Here is what occurs: When I go to start the engine, the alarm sounds and doesn't go off. When the engine starts, the alarm continues to go off. The engine purrs, the oil level is correct. The engine oil gauge is pegged to 0 and the alarm board is lit at the engine oil pressure. I have taken the boat out for a drive three different times and the alarm continues to sound. The Starboard engine sometimes stalls and putters if given to much throttle, sometimes, it's even hard to get it started again.
What I have done: I have given this engine a complete tune-up, as it sat in the slip for two years (old gas, oil change within a year). I have changed out the oil sender. This was done, prior to taking it out on the water a third time. Still, the issue exists.
My next move is to connect the oil pressure tester to make sure I have oil pressure, which I'm sure I do. I have noticed another sender near the distributer, which looks similar to the oil sender at the bottom of the block (port side). I have searched several manuals and the mercury parts store, but can't seem to find this sender. I asked one mechanic from the marina, and he said it was an oil pressure sender for the alarm. From what I have read, it sounds as though a sender is failing and the alarm is sounding, thus effecting the fuel pump to send fuel. I am lost. Any help would be greatly appreciated.

 

[achris]

Hello and welcome to iboats.

One of the most useful pieces of information you can provide is the engine serial number. You've also not said if it's carbed or EFI/MPI...

I'll assume carbed...
I've looked at the wiring drawings and I don't see an electric fuel pump anywhere, so it's probably mechanical (the beauty of a serial number, I can look all that up)...

There are 2 'oil pressure sensors' on your engine. One is the sender for the gauge (located on the port side of the engine block) and the other is a switch, located near the distributor. The 2 are completely separate and don't influence each. If you have a zero reading on the gauge, ground the light blue wire on the sender and see if the gauge pegs high. If so, replace the sender.

If the alarm is constantly sounding, then just disconnect the tan/blue wire from the oil pressure switch and if that's the fault, the alarm will stop.

If you have an oil pressure alarm AND a zero gauge reading, it's more likely you actually have no oil pressure.

Chris......

 

[Bt Doctur]

The oil pressure sender will not alarm if no pressure is present. The oil pressure alarm will alarm with no oil pressure as well as high engine temps.
oil pressure senders unlike the alarm wire. will have a light blue wire attached
switch

 

[Bt Doctur]

Pressure Senders & Switches | Senders and Sensors | VDO Instruments and Accessories

www.vdo-gauges.com

 

[Bondo]

We purchased a 1992 Sea Ray 400 EC this May and we have had none stop issues with the Starboard engine. The engine is a 7.4L MIE (LH) Gen V GM 454. Here is what occurs: When I go to start the engine, the alarm sounds and doesn't go off. When the engine starts, the alarm continues to go off. The engine purrs, the oil level is correct. The engine oil gauge is pegged to 0 and the alarm board is lit at the engine oil pressure. I have taken the boat out for a drive three different times and the alarm continues to sound. The Starboard engine sometimes stalls and putters if given to much throttle, sometimes, it's even hard to get it started again.
What I have done: I have given this engine a complete tune-up, as it sat in the slip for two years (old gas, oil change within a year). I have changed out the oil sender. This was done, prior to taking it out on the water a third time. Still, the issue exists.
My next move is to connect the oil pressure tester to make sure I have oil pressure, which I'm sure I do. I have noticed another sender near the distributer, which looks similar to the oil sender at the bottom of the block (port side). I have searched several manuals and the mercury parts store, but can't seem to find this sender. I asked one mechanic from the marina, and he said it was an oil pressure sender for the alarm. From what I have read, it sounds as though a sender is failing and the alarm is sounding, thus effecting the fuel pump to send fuel. I am lost. Any help would be greatly appreciated.

Ayuh,..... Welcome Aboard,..... Lotsa great info above, 'n I'll run with what Chris assumes, if it's carbed, there's 3 trigger switches that activate the alarm,.....
An oil pressure switch, as Chris mentions,....
An over-heat switch in the t-stat housin', near the temp sender,.....
'n a drive oil bottle switch, in the drives oil bottle,.....
Any of the 3 can be bad, 'n trigger the alarm,..... they just ground out the buzzer,...