2000 Yamaha F100 four stroke oil alarm goes off at first and then goes away

[tavacska]

My engine is 2000 Yamaha F100 which is running very good.

The oil alarm goes off immediately upon starting the engine the first time on water. I stopped the engine, removed the filter, and attempted to clear every droplet before reinstalling it. After several cycles of turning the engine on and off and engaging it, the alarm stopped.

After returning home, I replaced the oil filter and performed an oil change. However, a month later when I got back on the water, the same issue recurred. After repeated cycles of turning the engine on and off and allowing it to idle for some time, the alarm ceased once more. I spent the rest of day on the water with no issues.

Could this be a faulty oil pressure gauge? It appears that the system only functions properly once the oil warms up.

Thank you.

 

[dingbat]

Could this be a faulty oil pressure gauge? It appears that the system only functions properly once the oil warms up.

Could be the oil pump, pressure switch or wiring.
Not going to know which w/o some testing.

 

[99yam40]

from what I have read, the alarm is an out of normal range of pressure for the RPM at that time.
could be too low or too high.
I would tee in a gauge to see what the pressure is doing when it alarms and when it goes away

 

[tavacska]

Thanks for the replies. Here is the updates:
As I was to test the oil pressure with a mechanic gauge, I found the attachment screw was loose causing the on-and-off alarms.
Easy fix but cost me days of thinking.

 

[99yam40]

good to here it was an easy fix.
I guess you found a loos electrical connector.
never know what you can find as a problem

 

[dingbat]

As I was to test the oil pressure with a mechanic gauge, I found the attachment screw was loose causing the on-and-off alarms.

Easy fix but cost me days of thinking.

Always start with the simplest possible problem and go from there, i.e. check for a clogged fuel filter before rebuilding the carbs

 

[tavacska]

I know it was too good to be true to solve the problem on first try
.
Last Sunday when I headed out, the alarm went off again when I first started the engine. After half a minute, the alarm was gone.

After idling and trolling for half hour, especially when I tilted up the engine to reduce my trolling speed to 2 mph, the alarm went off again. However, it was perfect whenever it revs up and on plane.

Today, I did an oil pressure test with a mechanic pressure gauge connected. The pressure shows:
RPM 1000-2000, 70 psi and keep at that value
RPM 900, 50 psi
RPM 600 (idling), 40 psi, sometimes fluctuate to 30 psi (idling 10 mins)

I also did a bench test on the oil pressure switch. It discontinues when > 25 psi, it is short on < 25 psi.

My question is, will this driveway test be good enough to confirm that the oil pressure is OK? Is there any chance the read could be different on water.

Anyway, I have placed an order on a new switch, which maybe has some debris block problem or glitch. Any thoughts?

 

[dingbat]

I also did a bench test on the oil pressure switch. It discontinues when > 25 psi, it is short on < 25 psi.

My question is, will this driveway test be good enough to confirm that the oil pressure is OK? Is there any chance the read could be different on water.

Anyway, I have placed an order on a new switch, which maybe has some debris block problem or glitch. Any thoughts?

You can try a new switch, but I don’t think that’s your problem seeing your testing showed it's operational.

As a final test, I’d put a meter on the switch during operation to see if the signal is dropping out on you.

Pressure switches are typically pretty robust. Still think you have a downstream electrical problem.

Using an OEM oil filter?

Where is the power to the pressure switch coming from?