OMC 5.0 Stalls coming off gear

Martti

Cadet
Joined
Oct 9, 2018
Messages
6
Hello fellow boaters,

I have got a problem with my OMC 5.0 (at Bayliner 1952 1989) with OMC cobra sterndrive. When coming off gear it stalls.

Lower shift cabel seems to be ok and I have adjusted it. It shifts nice by hands. Video is taken coming of R by hands. If ESA is unplugged, I can't get out of gear at all (as it is supposed to be), and if ESA is plugged I can get out of gear, but it stalls immediately.

I have read and watched all the info about this problem, but can't seem to solve it. I think the issue is that the motor stalls. I believe it is supposed to only run rough, but not stall. I think the ESA works fine, and it is doing it's job as it is supposed to.

I also have the MSD box, coil, and distributor.

Do you have any ideas what to do for the engine not stall? I don't know what the rpm is at idle, because I haven't been able to make the tachometer work yet. It idles great though.

I bought this boat couple of years ago as a total wreck just for a project to build, and now it is in the water, with this only problem stopping me for enjoying it. I myself am more as a carpenter than a mechanic, so my understanding about this is pretty limited, but I am eager to learn.

I am writing from Finland, so sorry about my possible bad english.

So many thanks in advance, for any help.

Br, Martti
 

Martti

Cadet
Joined
Oct 9, 2018
Messages
6
I have done more research, and I am pretty sure it is about that connection to the MSD 6A which is causing the stall.

The shift assist swich is connected straight to the MSD 6A box, with it's white wire. Here is video what happens, when switch is pressed:

https://youtu.be/aAPeKGrCL3A

So it cuts out the ignition straight away.

I have read about that "diodefix", people have made to fix this. Now I am wondering where should I put it. I made this picture of the wiring, and would like to ask your opinions about where to put the diodefix. Black lines are how it is connected right now.

Do you know what is the right way to connect the diodefix? Red, blue, or green, or something else?

Grateful for all the help, thank you.

Br, Martti
 

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Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
Ok your engine originally came with a points style ignition and the OMC electronic shift assist module (ESA). When properly adjusted this setup will not stall when shifting, what happens is that the engine idle rpm drops from 600 to approx 450 rpm. The issue is that the engine must be in good enough tune to run at 450 at least momentarily. My 88 4.3 V6 with the Rochester Quadrajet is able to do this, it’s never stalled when triggering the ESA. I’d get a tach/dwell/volts/amps multi meter you have to know your idle rpm to get this fixed. About the diode fix, look on the Petronix website, they have info on the diode fix for use with their electronic ignition system conversions. This is why I am an advocate for keeping the old points type system on these engines and not converting to electronic, when the points are maintained it works just fine. Converting to electronic introduces more unknowns...
 

Lou C

Supreme Mariner
Joined
Nov 10, 2002
Messages
11,802
However there are other options, you might try contacting CDI electronics in Huntsville Alabama USA. They make ESA units for OMC engines and might’ve able to advise you on which one works with electronic ignition...
 

Martti

Cadet
Joined
Oct 9, 2018
Messages
6
Thank you for your reply.

I really don't know the reasons why there is this MSD ignition installed. It was like this when I got it.

Engine runs really great, though. I managed to get the tach to work, but I am not very sure about how accurate it is, since my multimeter doesn't have Hz in it. It now looks like the idle speed is about 600-650, and it starts to stumble at about 400-450 rpm (when adjusting idle from idle screw).

The petronix diode fix says to put the fix between ESA and coil -. This is the red choice at my drawing. All though the MSD manual says 'the only two wires going to the coil should be from the ignition box". So I am thinking could I possibly fry something by trying that fix, if it is totally wrong?

I know there is people out there who has done these with OMC and MSD. I just can't find these people. I even found one who has done it here in Finland at this one boating forum, but he didn't tell how exactly the wiring went and I can't get any replys from anybody at that forum (because there is something like 5 active people at the forum).
 
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