Oil pressure alarm issue

[Quicksupra]

I have a 2006 225hp four stroke yamaha which is setting off the oil alarm. The gauges are the standard non digital yamaha version. The engine runs fine with no strange noises and the oil level and quality look good. The alarm will go off at no wake speeds but not at any cruising speed. It will cut the throttle if its revved in neutral. The alarm will turn off by turning the key off but will come back on after the engine is running at exactly 1 minute 15 seconds. Ive had a yamaha repair person to the boat when it started this issue. He found no codes stored in the computer and said the engine oil pressure at idle was 86 and everything looked good. The alarm did not go off while he was looking at it in the slip. When this first started I replaced the oil pressure sender but this did not fix the issue. None of the local repair shops has a mechanical oil pressure gauge for sale so I can't check it that way. Any ideas on what to look at next? Thanks

[rodbolt17]

the 5v reference voltage can be jacked by another sensor failing.
most techs cannot seem to wrap their tiny brains about it.
the laptop is only going to show garbage in garbage out.
that motor will toss a code for low oil pressure at a given RPM and HIGH oil pressure at a given RPM.
its stupidly simple yet most techs cannot grasp it.
kinda like precision blend.

[Quicksupra]

I have three 2005 F225s. I've had to replace two OPS at 450 hours on two engines as they failed. I got a code 39 on both. The replacement OPS was from a Yamaha dealer (SIMs up north), and they were expensive, and they had a much bigger hex nut, as Yamaha has had issues with these OEM sensors.

The mechanic put your engine on his YDS and says the oil pressure is good, but if the alarm is going off all the time, you need to find out why.

I have the Yamaha YDS and can put my engines on a laptop and read the oil pressures any time I want, and that might be a good investment for you for a few $100. The YDS is useful as it will tell you what is setting off every hard code and every alarm. I purchased an oil pressure gauge from Andy as he was able to find one Andyjr@shipyardisland.com

You definitely want to know what your oil pressure is on that engine. The fact that your alarm goes off at low speeds may or may not mean much. mine went off at high speeds when they failed, and all the time on start ups after that until I replaced the senders.

One of the mechanics (Rodbolt17, Boscoe, so on and so forth) may be able to solve your OPS alarm issues, and I wish you luck.

Finally, if you OPS alarm is going off, you should be getting a Code 39 on your YDS. I don't understand why you are not.

Does the engine idle higher after the alarm goes off? Are you sure it's an OPS alarm, and not a temp alarm or other alarm? On your tach, you would get a blinking three times followed by a blinking 9 times for a Code 39. Are you getting this Code 39 reading?

The oil light on the tach comes on with the alarm not the temp light. The engine doesn't change at all when the alarm comes on. The light stays on and does not blink at all. Turn the key off and restart and the light stays off for exactly 1 minute 15 seconds then comes on again.

[Quicksupra]

the 5v reference voltage can be jacked by another sensor failing.
most techs cannot seem to wrap their tiny brains about it.
the laptop is only going to show garbage in garbage out.
that motor will toss a code for low oil pressure at a given RPM and HIGH oil pressure at a given RPM.
its stupidly simple yet most techs cannot grasp it.
kinda like precision blend.

How would I determine which sensor is causing the issue? The motor is not showing any codes at all. The issue I'm having is only at low rpms in the no wake zones ie 1k rpm. I've checked the connections to the ops and all around the engine and things look ok. The batteries are charged up and I'm getting 14v when running. What would be the next step to figuring out the problem? Thanks for the help.

[rodbolt17]

most likely, your going to have to have the laptop hooked up when the alarm triggers.
like I have said in the past, not like most actually UNDERSTAND, that these motors oil pressure feed back is a MAPPED thing.
means the ECU is looking at a voltage feed back VERSES an RPM signal.
means the ECU will toss an alarm if the oil pressure voltage feed back is ABOVE or BELOW a mapped program fo a given RPM.
if ANY other sensor is loading the 5v ref then the ECU will toss an alarm for something.

this ECU is basically a stupid set of truth tables.