MerCruiser 5.0 MPI diagnostic connector

[ZafSC]

i would start by changing the distributor cap , while you are in there check the cam sensor , if its not that expensive replace it , those two things can be questionable at the best of times ,
although the cam sensor usually just dies and gives no readings they have been known to cause erratic spark @ high RPM which is IMO what 'is going on..

your motor also has a crank sensor , that also usually just dies and again they have been known to cause erratic timing if they are not calibrated correctly with the proper tool.

timing must be set with the correct tool , if not done this way you will never get correct timing.

has the motor been checked with a diagnostic tool , , if so were any codes showing ?.

Hello. Sorry but where is the diagnostics connector? I am posting a picture of my engine, can't locate the 10-pin connector :-( Pretty much looked all around it. Maybe there is none?
Thanks

 

[southkogs]

@ZafSC I moved this to a new thread for you. - I left the quote in to direct people to the thread you asked your question in initially.

Welcome aboard.

 

[badfish29]

It's going to be under that large plastic cover on top. Here's a picture of mine and it's labeled diags/depth finder.

 

[Scott Danforth]

Hello. Sorry but where is the diagnostics connector? I am posting a picture of my engine, can't locate the 10-pin connector :-( Pretty much looked all around it. Maybe there is none?
Thanks

Boat motors do not use the automotive ALDL connector or OBD software

You will need Rinda software

Many things can be diagnosed easy without plugging in.

What is the motor doing or not doing?

 

[ZafSC]

It's going to be under that large plastic cover on top. Here's a picture of mine and it's labeled diags/depth finder.

View attachment 377448

Thanks I found the connector exactly at the same point. I was looking for one with 10 pins, this one has only four (just like a trailer connector).
So in order to find the diagnostics codes, I guess I need to short two pins and the engine hopefully goes to service mode and starts blinking a LED connected (or beeping a multimeter) on the other two pins.
Are those the correct pins on the picture for this setup?

 

[ZafSC]

Boat motors do not use the automotive ALDL connector or OBD software

You will need Rinda software

Many things can be diagnosed easy without plugging in.

What is the motor doing or not doing?

I had the engine checked at a mechanic, and he showed me the fuel pump half full, and he said engine wasn't working at full efficiency. He said either air is coming, or fuel is leaking. Then I took it on the water, and he was right, it stalled sometimes, especially when putting into gear. I had to restart it several times, and no problem, always started. I didn't notice a fuel leak in the bilge area, but it does smell heavy in the engine compartment. New spark plugs, new fuel filter. So I am investigating. This is my first boat so there is a lot of learning. I am comfortable with car engines though.

 

[dubs283]

I guess I need to short two pins and the engine hopefully goes to service mode and starts blinking a LED connected (or beeping a multimeter) on the other two pins.
Are those the correct pins on the picture for this setup?

No, anything mercruiser produced after mefi (555 or later) does not have the capability of "winky blinky" technology. At least not without the proper diagnostic equipment

If you want to view fault codes you need at least diacom/rinda or mercs proprietary cds. Neither of which will tell you anything about the fuel pump

Based on posted info you need to first check fuel pressure/vacuum and possibly the lower shift cable actuating the interrupt switch prematurely.

FYI, the distributor cap on your setup is a common culprit for runnability issues and is a routine maintenance item

 

[04fxdwgi25]

I had the engine checked at a mechanic, and he showed me the fuel pump half full, and he said engine wasn't working at full efficiency. He said either air is coming, or fuel is leaking. Then I took it on the water, and he was right, it stalled sometimes, especially when putting into gear. I had to restart it several times, and no problem, always started. I didn't notice a fuel leak in the bilge area, but it does smell heavy in the engine compartment. New spark plugs, new fuel filter. So I am investigating. This is my first boat so there is a lot of learning. I am comfortable with car engines though.

My main concern would be the fuel smell in the engine compartment. That is how majority of boat fires / explosions start.

Can't blame a flooded carb, since it is MPI.