1993 OMC 5.8 EFI and drive system conversion to Volvo Penta

[Rhc]

doesn't look too high, when you trigger the interrupt switch, does it drop the RPM in neutral to about 450?

 

[Rhc]

Good day Lou,
I did the test you suggested. I put it in neutral and triggered the interrupter and yes the RPM drops to about 450.
Then I put it in gear and triggered the interrupter and the RPM drops as above. Maybe if the two Micro switches are not in series but say parallel, the results are quite different. I have confirmed

• My interrupter in neutral the rpm drops if I triggered
• My o/s (overstroke) is NO in gear per ohm meter at infinity
• My o/s when in neutral is a closed circuit.

We need a schematic drawing showing the arrangement of these two micro switches. Do you have such? Where can we find this?
Tracing, the wires is not an easy option.
What are your thoughts and suggestions?
Thanks Bob

 

[Rhc]

View attachment 1727401944435.jpeg

 

[Rhc]

The EFI seems to hold the info we are missing dealing with a NDS and SAS micro switches.

 

[Lou C]

Well the only thing I have as far as that goes, is the wiring diagrams for the original style ESA which was actually part of the ignition system. So I don't think what I have is going relate to how yours should work, but I still think the interrupter should not activate with the drive in gear. Maybe that overstroke switch isn't functioning. Looking at the last image you posted I can see how far beyond the tech on your engine is compared to mine. Mine is like a '66 Chevy, yours is like an early 90s Mustang. I think you need a factory shop manual, with factory wiring diagrams and troubleshooting steps....

 

[Rhc]

Well the only thing I have as far as that goes, is the wiring diagrams for the original style ESA which was actually part of the ignition system. So I don't think what I have is going relate to how yours should work, but I still think the interrupter should not activate with the drive in gear. Maybe that overstroke switch isn't functioning. Looking at the last image you posted I can see how far beyond the tech on your engine is compared to mine. Mine is like a '66 Chevy, yours is like an early 90s Mustang. I think you need a factory shop manual, with factory wiring diagrams and troubleshooting steps....

Thanks for all your help. I will keep you updated if I find anything.

 

[Lou C]

Original outboard product and service manuals for Johnson, Evinrude, Gale, and OMC

Ken Cook Co. sells Original Product Literature Supporting 1996 and Older Outboard Marine Corporation Products, limited supply of original printings of Johnson, Evinrude, Gale, and OMC manuals are still available. On older literature, we may provide a machine copy reproduced from a master file...

www.outboardbooks.com

OK found the link I was looking for, this is for factory OMC manuals, they may not have your exact model number but if you call them you might be able to get a manual that is close enough, and if you look at what's available, they also do have troubleshooting manuals for the EFI, etc.
I feel fortunate that mine is a stone age simple one with a Prestolite points distributor and a 4 bbl Quadrajet, both of which I grew up with on cars of the '70s.

 

[Rhc]

Original outboard product and service manuals for Johnson, Evinrude, Gale, and OMC

Ken Cook Co. sells Original Product Literature Supporting 1996 and Older Outboard Marine Corporation Products, limited supply of original printings of Johnson, Evinrude, Gale, and OMC manuals are still available. On older literature, we may provide a machine copy reproduced from a master file...

www.outboardbooks.com

OK found the link I was looking for, this is for factory OMC manuals, they may not have your exact model number but if you call them you might be able to get a manual that is close enough, and if you look at what's available, they also do have troubleshooting manuals for the EFI, etc.
I feel fortunate that mine is a stone age simple one with a Prestolite points distributor and a 4 bbl Quadrajet, both of which I grew up with on cars of the '70s.

Thanks so much again. I have Selco book which is where I found the photo top view of the motor and micro switches will different names. There is a whole lot of information on EFI and fuel systems. I’ll do some reading on this over the weekend and perhaps maybe enough there to help. Cheers Bob

 

[Lou C]

Good luck with it and let us know what you find out!

 

[Rhc]

Good luck with it and let us know what you find out!

I found this info using AI to review OMC documents.
Here’s a breakdown of the differences between the two switching systems used in the OMC Cobra drive:

1. Neutral Switch and Overstroke Switch (Pre-1993)​

• Neutral Switch: This switch ensures that the engine can only be started when the drive is in the neutral position. It acts as a safety feature to prevent the boat from starting in gear, which could cause sudden movement and potential accidents.
• Overstroke Switch: This switch is part of the shift assist mechanism. It helps to manage the shifting process by ensuring that the shift cable moves correctly and prevents over-extension, which could damage the drive system.

2. Neutral Safety Switch (Post-1993)​

• Neutral Safety Switch: In 1993, OMC simplified the system by integrating the functions of both the neutral switch and the overstroke switch into a single neutral safety switch. This switch still ensures that the engine can only be started when the drive is in neutral, maintaining the safety feature. However, it also incorporates the shift assist function, streamlining the system and reducing the number of components that could potentially fail.

Key Differences​

• Component Reduction: The newer system uses fewer components, which can reduce the likelihood of mechanical failure and simplify maintenance.
• Integrated Functionality: By combining the functions of the neutral and overstroke switches into one, the neutral safety switch provides a more streamlined and efficient operation.
• Improved Reliability: The newer system is generally considered more reliable due to its simplified design and reduced number of moving parts.

 

[Lou C]

AI isn’t that smart lol; they mixed in the neutral safety switch which is mounted on the remote control with the interrupt switch! One has nothing to do with the other. What I read was that they encorporated a timer into the ESA module and eliminated the overstroke switch; yet yours has 2 switches!

 

[Rhc]

AI isn’t that smart lol; they mixed in the neutral safety switch which is mounted on the remote control with the interrupt switch! One has nothing to do with the other. What I read was that they encorporated a timer into the ESA module and eliminated the overstroke switch; yet yours has 2 switches!

Here is a more detailed version of change per AI. We still would benefit with schematic drawing.

Sent by Copilot:​

Certainly! Here’s a comparison of the shifting methods before and after the changes OMC made in 1993:

Shifting Method Prior to 1993:​

1. Forward or Reverse Gear Engaged:
   • The engine is running, and the boat is moving either forward or backward.
   • The interrupter and overstroke switches are in place.
2. Initiating Shift to Neutral:
   • You move the control lever towards the neutral position.
   • The shift cable moves the shift mechanism in the lower unit.
3. Interrupter Switch Activation:
   • As the shift mechanism moves, the interrupter switch is momentarily activated.
   • This briefly interrupts the ignition, reducing engine RPM and easing the shift.
4. Overstroke Switch Activation:
   • The overstroke switch ensures that the shift mechanism has fully engaged the selected gear.
   • If the shift mechanism does not fully engage, the overstroke switch will prevent the engine from running properly, indicating an issue with the shift.
5. Neutral Position Achieved:
   • The shift mechanism reaches the neutral position.
   • The neutral safety switch closes the circuit, allowing the engine to start again if needed.

Shifting Method After 1993 Changes:​

1. Forward or Reverse Gear Engaged:
   • The engine is running, and the boat is moving either forward or backward.
   • The shift assist solenoid and neutral drive switch are in place.
2. Initiating Shift to Neutral:
   • You move the control lever towards the neutral position.
   • The shift cable moves the shift mechanism in the lower unit.
3. Interrupter Switch Activation:
   • As the shift mechanism moves, the interrupter switch is momentarily activated.
   • This briefly interrupts the ignition, reducing engine RPM and easing the shift.
4. Shift Assist Solenoid Engagement:
   • The shift assist solenoid may momentarily engage to help complete the shift into neutral.
5. Neutral Position Achieved:
   • The shift mechanism reaches the neutral position.
   • The neutral drive switch closes the circuit, allowing the engine to start again if needed.

Key Differences:​

• Components: The interrupter and overstroke switches were replaced by the shift assist solenoid and neutral drive switch.
• Functionality: The shift assist solenoid provides additional assistance during the shift, which was not present in the pre-1993 system.
• Reliability: The updated system with the shift assist solenoid and neutral drive switch offers smoother and more reliable shifting, reducing the likelihood of incomplete gear engagement.

These changes were aimed at improving the overall shifting experience, making it smoother and more reliable. If you have any more questions or need further details, feel free to ask!

 

[Lou C]

I’d love to see what the official factory shop manuals says!

 

[Rhc]

Yah so I will ask OMC dealer to see his manual!! I will do pics for us all

 

[Rhc]

A lot of the EFI information is available in a manual I have. It is SELOC — OMC Stern drives 1986–98. I also have OMC COBRA manual for models MED & MEF. Earlier versions of my engine. That is where I found new names NDS & SAS - I sent you pic of engine earlier.
Cheers more to follow.

 

[matt167]

Seloc manuals generally hold up the broken leg of a coffee table. They have accurate specifications but repair procedures are often incorrect. Critical points like shift adjustment is totally wack, for sure on Mercruiser. I’m sure OMC/ Volvo is similar

 

[Rhc]

Seloc manuals generally hold up the broken leg of a coffee table. They have accurate specifications but repair procedures are often incorrect. Critical points like shift adjustment is totally wack, for sure on Mercruiser. I’m sure OMC/ Volvo is similar

Thanks for your input. Could you tell me if you have the manual for my model #58FAPRJVN. ( 1993 OMC COBRA 5.8 EFI AND ESA features) . If so could you provide a picture of the written operation of the so called EDS (neutral drive switch) and SAS (shift assist solenoid). Previous to 1993 these were called Interrupter switch and overstroke switch. Perhaps the manual has the wiring diagram?
Thanks