2002 F115 Oil Pressure Warning

[twirk_twirk]

I am just posting to follow this thread. I am having a very similar problem with my F115 and am interested to see how your problem turns out.

[JONSNELL]

Oil pump replaced and 2 trips down and all is good.

I know this has happened before and didn't want to say too much too soon but I do feel confident that we have it nailed this time.

A very frustrating problem and difficult to trouble shoot/ diagnose when it doesn't happen all the time.

Fingers crossed - also replaced the lower crank seal while we had the power head off.

[twirk_twirk]

They attended to this but also reported that they tested the voltage form the battery and standing voltage was over 12v but on start it was dropping to 7v. They replaced the battery cables.

What is the Amp Hours (AH) rating of your battery?

[JONSNELL]

I use an Optima D34M - 55AH 750CCA

[twirk_twirk]

I use an Optima D34M - 55AH 750CCA

I'll tell you what. I believe your battery is not big enough for the F115.

The attached photo is straight out of the owners manual. You'll see that Yamaha tells the amp hours should be between 100-120AH (you have 55AH, I am/was running 60AH).

Now, apparently a lower AH rated battery can crank the outboard over just fine, but as your mechanic noted, the voltage drops from ~12V to ~7V and that is when your ECM shuts down and that's when anything con*****ed by your ECM can be damaged (think: high pressure fuel pump, oil switch, intake air pressure sensor, etc etc.). Add to that if you have a chartplotter, fishfinder, VHF hooked up to the same battery thats sucks even more power. You are in for some trouble.

I just realized this a few days ago, so I have not had time to buy a battery spec'd as Yamaha suggests yet. But I will bet that is the problem.

I've had VERY similar problems to you with my F115, and have done numerous things to remedy the problem. This has lasted me about a year now.And honestly, I have tried so many of the same things you have. Fuel line, idle speed control, charged battery, cleaned fuel injectors, changed the ECU, spark plugs, different oil, voltage regulator, oil switch, took apart the throttle control, cleaned changed high pressure fuel pump, changed every filter, atmospheric pressure sensor etc etc. Literally everything I could possibly chase, I chased. Except checking to see if my battery was the right battery size.

And I just couldn't figure out why things seemed to keep breaking down, when the engine seemingly ran like a champ at higher rpms.

If I have time tomorrow I will find a new battery and begin testing.

I am going to link to my thread on The Hull Truth, just so you can follow along there. Will Yamaha diagnostic software point to faulty ECU? - The Hull Truth - Boating and Fishing Forum

I hope you find this useful. I would like to fix my engine and help others who are experiencing the same puzzling problems.

[JONSNELL]

5 trips down and no Oil Pressure warning so I'll make the call that it is fixed.

Now I have a squealing noise - I'll start another post.....