Overstrock or interupt switch,

[merit131]

I have a 1989 4 winns 302 ford OMC Cobra, My problem is when I shift into forward or reverse, everything is fine, goes into gear, but when I give it a little gas (trottle up) the engine dies. could it be one of these switches of the ESA.

 

[merit131]

Re: Omc cobra overstroke and interuptor switch

Re: Omc cobra overstroke and interuptor switch

You state the intrrupt switch and the overstrock is a NC switch, ( what does NC mean) I have a weired problem. I have a 1989 4 winns 302 ford OMC Cobra, My problem is when I shift into forward or reverse, everything is fine, goes into gear, but when I give it a little gas (trottle up) the engine dies. could it be one of these switches of the ESA. This only happens when the boat is in the water, weired.

 

[merit131]

Overstrock or interupt switch,

I have a 1989 4 winns 302 ford OMC Cobra, My problem is when I shift into forward or reverse, everything is fine, goes into gear, but when I give it a little gas (trottle up) the engine dies. seems electrical, could it be one of these switches of the ESA. That only happens when the boat is in the water. When it's in my driveway, it seems fine. weired. problem after problem, all I want to do is get on the water and go. any advise please. I checked out some old post and got some dia and problems w/ tramson gear shift and it all makes perfit sense. I'm thinking overstrock switch. and what does this ESA box really do? thanks. Jack Murphy

 

[bruceb58]

Re: Omc cobra overstroke and interuptor switch

Re: Omc cobra overstroke and interuptor switch

You need to start a new thread.

 

[merit131]

Re: Omc cobra overstroke and interuptor switch

Re: Omc cobra overstroke and interuptor switch

I just did.

 

[bruceb58]

Re: Overstrock or interupt switch,

I doubt it's your ESA but there is an easy check for that. Just unplug it and see if your problem goes away. Just be aware that you may find it difficult to get it out of gear so do this in a place where you won't run into anything.

The ESA is supposes to stumble the engine when going out of gear while in the water. When you are on muffs it should never operate because there is no load on the prop. If your lower shift cable is sticky, it may operate it. The reason you need to stmble the engine when going out of gear is so the dog clutch can release easier.

The purpose of the overstroke switch is to disable the ESA one you move your shifter fully into gear. Starting in 1990 or so, they got rid of the switch and replaced the ESA with one with a timer so you didn't need the overstroke switch.

 

[bruceb58]

Re: Overstrock or interupt switch,

Have you done a full tune up on your boat including fuel filters, points(setting dwell with a dwell meter), timing, rotor, cap...?

 

[merit131]

Re: Overstrock or interupt switch,

Yes, did a full tune up, filters, timing, rotor, cap, condenser, points, new plug wires, plugs, new coil. It shifts pretty smooth into both forward and reverse. No problem when I do this in my drive way, it all seems great. As soon as it goes in the water, I shift in reverse no problem but when I give it a little gas, it dies. Seems Electrical to me. So I assume it may have something to do with a load on the prop as you stated above. Maybe some type of adjustment, maybe to the shift cables or the inturuptor switch. But again only when it's in the water I have this problem. Jack Murphy

 

[bruceb58]

Re: Overstrock or interupt switch,

Doesn't sound electrical at all to me. Sounds like a carb issue.

What it does on the muffs doesn't matter since there is no load.

What is your timing and dwell sitting at out of curiosity? You adjust them to spec? Set dwell with a dwell meter?

 

[merit131]

Re: Overstrock or interupt switch,

I did the timing, would need to look up to let you know the setting it is at. The Dwell I have not done and don't know how, but will look up and have it done by a friend. Will get back to you. Thank you. Also while in the water. Engine runs great. I pull out the shift handle and I can give it gas, no problem, carb sounds good and the engine as healthy. I will let you know. Jack M

 

[bruceb58]

Re: Overstrock or interupt switch,

You always set the dwell and then set the timing as the dwell adjustment will affect the timing.

I pull out the shift handle and I can give it gas, no problem, carb sounds good and the engine as healthy. I will let you know. Jack M

That actually doesn't tell you much. You could have 2 or 3 dead cylinders and you would still be able to do that. I had 2 spark plug wires crossed once and you couldn't tell by revving the engine in neutral.

 

[merit131]

Re: Overstrock or interupt switch,

I purchased a dwell meter on ebay should have it soon for results, and I will get back to you. Could you tell me a little about the interupt switch. What it does and how to adjust it if possible.

 

[bruceb58]

Re: Overstrock or interupt switch,

As you shift out of gear under load, tension of the cable pulls the "W" shaped cam across the roller of the interrupt switch. When this switch is operated, it turns on the ESA which pulses the negative side of the coil causing the engine to stumble. The interrupt switch should ride in the center of the big detent of the cam. This assumes you are in neutral and the lower shift cable is in good shape and not binding.

The following picture shows where the switch should be at all times except during shifting out of gear while in the water.

 

[Ttigger]

Re: Overstrock or interupt switch,

Great photo.
How much should that "W" cam move when shifting? Mine barely moves and does not always trip the ESA switch. Is it's travel adjustable?

 

[bruceb58]

Re: Overstrock or interupt switch,

Great photo.
How much should that "W" cam move when shifting? Mine barely moves and does not always trip the ESA switch. Is it's travel adjustable?

It will only travel enough to trip the switch when you are IN the water, shifting OUT of gear. If you are looking at it shifting out of the water on muffs, it will only do as you describe.

 

[merit131]

Re: Overstrock or interupt switch,

Thank you for a great picture and explanation on this interrupt switch and the correct spelling, lol, I understand now how the ESA works and what it does. If you don't mind, could you also explain to me what the overstrock switch does. I did find a link on this sight which gave me Hasting or maybe from the OMC Service Training. Hope it pops up.

 

[merit131]

Re: Overstrock or interupt switch,

Now that I posted a picture of a document here are two others for anyone who needs to know the five steps of the Engine Shift Bracket Adjustment. Hope it helps. Wish I still had the link to all these documents I found on this site. I found to be very helpful. But it did not state what the overstrock and the interrupt switches did.

 

[bruceb58]

Re: Overstrock or interupt switch,

What the overstroke switch does is open up the circuit when you are all the way into gear. Like I said before, the interrupt switch shouldn't operate while going into gear. Unfortunately, as the cable ages, the interrupt switch may start operating going into gear and stay on the high side of the cam when you are in gear, The overstroke switch prevents the ESA from operating once you are all the way into gear no matter what the interrupt switch is doing.

Later versions of the OMC ESA, starting in the early 90s, stopped using the overstroke switch. Instead, the ESA has an internal timer that only stumbles the engine for a few seconds once the interrupt switch is triggered. If you buy one of these ESAs, the plug for the new ESA bypasses the overstroke switch so you don't have to do any new wiring. When I had my OMC, I switched to this ESA.

 

[MRS]

Re: Overstrock or interupt switch,

View attachment 216489Now that I posted a picture of a document here are two others for anyone who needs to know the five steps of the Engine Shift Bracket Adjustment.View attachment 216488 Hope it helps. Wish I still had the link to all these documents I found on this site. I found to be very helpful. But it did not state what the overstrock and the interrupt switches did.

This is the five steps people do not do and is very important to the final adjustment for all the cables to work right.

 

[merit131]

Re: Overstrock or interupt switch,

Great information, I think I will pick up that new ESA as you stated, one less switch to worry about. Still waiting on my ebay delivery of my new dwell meter. I'll make sure all that in correct first, the dwill and the timing. Then I'll let you know what the reading are. I do have the specs on the dwell and the timing. Then I'll drop it in the water and see what happens. If it still cuts off as it did before. I'll install that new ESA. If I'm still having problems, I'll need to do that "Five steps of the Engine Shift Bracket Adjustment". Thank you, it seems to be coming together. Now that I know the purpose of these switches and the ESA and how they they all work together. I'll be back as soon as I have the info on the dwell and timing.