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?

 

[tavacska]

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?

Didn't have time on water until last night. Since last time, I have replaced the oil filter from an FRAM to an OEM filter. Your words reminds me and I did check internet and noticed FRAM oil filter cause a lot trouble on outboard.

However, every things start good until I am trolling for a long time at 600 RPM. The alarm goes off about 5 min when trolling. Then I put it to neutral and turn off the motor then restart the motor, and can keep trolling for another 5 mins. It repeats like this the whole time.

 

[99yam40]

I would hook up the pressure gauge again and monitor what the pressure is when the alarm sounds.
if the pressure is dropping down too low, you need to find out why

since you have run this motor with the alarm in several times,
there is a chance something was harmed due to no or not enough oil.
since you did use a possibly wrong filter, is there a chance you used the wrong oil also?

 

[tavacska]

I would hook up the pressure gauge again and monitor what the pressure is when the alarm sounds.
if the pressure is dropping down too low, you need to find out why

since you have run this motor with the alarm in several times,
there is a chance something was harmed due to no or not enough oil.
since you did use a possibly wrong filter, is there a chance you used the wrong oil also?

It IS wrong oil. It specs as 10W-30. I am using 5W-30 sythetic in Texas. Could that be a problem?

As for the oil pressure gauge, I do have the gauge ready but the position is so tight under the hood and hard to get those arranged out with the standard adaptors available. Maybe I need to remove the flywheel plastic cover but hesitated to do so. I will check closer and figure out a way.

And anther thing to note, the oil pan used to be very dirty. I used fluid diesel to soak for days and clean many times and changed the oil and filter many rounds until the strainer can't find any debris. Are there still any tiny debris clogged the filter again?

 

[99yam40]

I would try using the in spec oil , the 5W 30 is a thinner oil, so using the in spec oil could bring the pressure up some.

but with all the oil changes to clean/flush out the debris out of the oil system, there could be a problem from all that was in there and the lack of proper oil pressure/oil to lube the things that needed to be lubed.

 

[tavacska]

I would try using the in spec oil , the 5W 30 is a thinner oil, so using the in spec oil could bring the pressure up some.

but with all the oil changes to clean/flush out the debris out of the oil system, there could be a problem from all that was in there and the lack of proper oil pressure/oil to lube the things that needed to be lubed.

I changed to 10w30 as spec. Things got much better. Alarm went off only twice yesterday of 7 hours. I was trolling 80% of the time @600RPM. The spec RPM is around 850 as I remember, but I tuned it to 600-700 since it is carb 4 troke engine. Maybe that is another reason why it can have low pressure because of the low RPM at idling. It does not have low pressure alarm ever when the rpm is above 1500.

Do you think it's better to mix the 10w30 with 15w40 50/50?

Edit: speaking of RPM, the gauge shows 600 in water, I believe it is left site of 600. It maybe too low for the engine. I am considering to change prop 17 to 15 and increase the rpm to 700ish. I think the RPM does have an effect on the low pressure issue. I trimmed up the outboard a little up and it will be fine with less frequent alarm.

 

[99yam40]

a different prop or a small kicker motor for trolling might be the answer.
do they make things you can drop over into water to slow down the trolling speed( kind of like a drift sock maybe)