2004 Mercury 115 four stroke EFI code diagnostics

[c maas]

My manual says I can access the diagnostic codes with a two wire test light. The problem is I can only find one wire to plug into.
Can anyone tell me if there has been a change in the set up and my manual is out of date?

I'm trying to figure out why, after 750 hours, my engine has started making oil. Seems like the sensor codes are one place to look.

Thanks!

 

[rodbolt]

Re: 2004 Mercury 115 four stroke EFI code diagnostics

about the only sensor that could have an inrange failure and cause it to make oil is the coolent temp sensor.
usually we find a stuck open thermostat, the boat got heavy and can no longer turn 5800 RPM minimum with that days load, the fuel pump diaphram is leaking or carbon has stuck a ring or rings.
do a leak down test, post the results,if I miss it bump me on the yamaha forum. yes it can be tested with a home made lamp but I cant remember how as it only shows up in the mercury version of the F115 manual.

 

[Bently tri]

Re: 2004 Mercury 115 four stroke EFI code diagnostics

How can i access the diagnostics? I have a 2007 F115 EFI on a Bently with Faria gauges, so there is not a Mercury "trouble light". My boat runs full RPM just fine but misses at idle/ low rpm. My auto mechanic experience leads me to injector spray problems but they test fine. I am thinking TPS or map sensor situation especially as the tps looks exactly like the units that cause a part throttle problem on multiple chevrolets.

 

[1nebel0]

Re: 2004 Mercury 115 four stroke EFI code diagnostics

I have a 2004 115fuel injected four stroke and my miss at idle and off idle were two injectors not performing correctly... I sent the four out to Brucato and they flow them before and after they clean them. You get them back with a spec sheet showing what the clean up did..I believe for the 4 injectors it was $125...Made all the difference in the world..My buddy a marine mechanic says that Merc(Yamaha) four strokes are having issues with Ethanol...So what else is new... In my race boat I send the injectors out every year...cheap insurance from blowing a piston. One of my injectors on the 115 was flooding and one was running way lean...that can cause a detonation problem resulting in a hole in the top of the piston..Sent those out and you will be amazed..Go to their website as they are great people to deal with...Steve