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Nissan 25HP 4 Stroke EFI - Oil Warning Sensor

K

[email protected]

New member
Hi there,

I have a Nissan 25HP 4 Stroke EFI that keeps sounding the oil sensor alarm. This happens in very different scenarios and there does not seem to be a pattern to it, low speed, high speed, tilted, not tilted, cold and warmed up.

I changed the oil and filter and ensured the levels were good but I am still getting this problem.

Any suggestions on what I can do to diagnose the problem or a fix I should try first? Should I replace the sensor? Replace the oil pump? Something else?

Thank you in advance.

Ben
 
Either the pressure is low, or you are getting a false reading. I would install a mechanical gauge on the motor to determine which situation you have. If the actual measured pressure is OK, then you likely have a bad sender. If the pressure is actually low, you have a mechanical problem.
 
Quick update to my problem, replaced the sensor and tested the pressure, pressure is there and I am still getting an alearm. Local marina asked if I had purged the lines? NOt sure what is meant by this? Any thoughts on whaty else to check and what is meant by purge the lines?
 
Assuming the new sensor and the wiring are both good (if the wire grounds out it will trigger the alarm), it would then appear that you have a faulty ECU. Rather an expensive part. There aren't any oil lines to purge. They are likely thinking of the oiling system for a 2-stroke.
 
Thank you, would you happen to know the part number and cost for the ECU? Would there be any other areas to assess some sort of blockage etc. be it a line or some other area?
 
Another update, I spoke to a Tohatsu dealer and he asked aboiut the oil I used, I used the right viscosity but Quaker State automotive oil, he indicated that this could quite easily be my issue and to do a full oil and filter change again but using marine oil. Any thoughts on if this could actually cause my issue?
 
The preferred oil for that motor is 10w-30 type FC-W mineral (non synthetic) oil. The NMMA rating of FC-W means that it has anti-foaming and anti-corrosion additives. I doubt that automotive oil would cause such a low pressure.
 
[email protected] said:
Thank you, would you happen to know the part number and cost for the ECU? Would there be any other areas to assess some sort of blockage etc. be it a line or some other area?
Click to expand...
If you used a mechanical gauge and the reading was in the normal range, the only items that might be an issue are the sensor and the [expensive] ECU, and of course the associated wiring.
 
If a mechanical gauge shows good under the hole shot conditions, and you not have changed the sender twice, verify that the wire to the sender cannot ground out anywhere. At this point, something is causing the low oil indicator under acceleration only, so you either get a drop in pressure at that time, or the wire gets grounded out... or the ECU has a malfunction.
 
Thanks for all of your help with this Paul, I seem to be having not the greatest luck with this lately. When running it the other day the screw that holds the throttle/tiller handle on fell off and I can;t find it in the boat. I've also left my manual at the cottage and don;t have the ability to look the part number up. Would you happen to know the part number or the size and thread of the screw/bolt?
 
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