shift interrupter I THINK

[justspeed]

Guys,

I had an issue with ignition in my boat and I thought I had fixed it but its back again. And Now I have discovered something.

I have a 91 GM 3.0 4l Its outfitted with the OMC stuff and has the GM EST igntion

Anyways for some reason I have been beating my haed trying to figure out why the boat would not start. Seemed to try but would not start.

There are two plugs on the Dizzy. One for power and such and the other plug has two wires that you can clearly see go to the shift interrupter area. Funny thing. I unplugged that plug and engine fired right up. While running if I plug it back in engine stumbles badly.

My question is this. Can I run it like this? I know that rpms need to be low enough to shift. I get that. But does this being unplugged have any effect on timing? I have no idea whats going on. I checked both switches and there fine. I lowered RPMS down and shifted into forward and gave it some gas. Seemed to run fine and the shifter felt great of course. But is the engine running normal in this condition? I ask because I dont undertand the advance on this Dizzy and want to make sure I dont take it out on the water and have no power to get on a plain.

 

[jerryjerry05]

Re: shift interrupter I THINK

You can run it like that but the motor might not shift as good.Can be dangerouse when docking.
Be quick on the key,shutting it down.
The switch should read open(I believe) on a bench test.It grounds out the ignition to make the motor stumble so it relieves the pressure on the drive.
Replace it!!!
One switch is the overstroke the others called the cutout switch.Gotta figure out which is bad. Cutout switch????

 

[justspeed]

Re: shift interrupter I THINK

Thank you for response. I tried so hard last night to figure out what was bad with no luck.

With plug pulled from dizzy it starts and runs fine. Plug it in and engine stumbles bad.

I see the module and the two switches. There is a plug between them. I pulled plug and used test light to find all 4 wires were grounded. On that plug there is a wire from each switch and a blue wire that is just looped over. No idea what the issue is. Glad I found problem but now need to solve it.

You are sure leaving unplugged from dizzy has no effect on timing at all? Cause if that's the case then for testing I will lower idle and add a throttle return spring that will bring that idle down to 500 rpm or so which is what the system that has failed was doing.

 

[bruceb58]

Re: shift interrupter I THINK

Sounds like someone changed the distributor to the EST(good choice by the way) and changed how the shift interrupt works(original dist uses the ESA). Sounds like the shift interrupt switch is held closed. This can happen from a faulty switch, out of adjustment switch, or your lower shift cable is failing causing binding which keeps the switch engaged. My bet is on the last one.

 

[justspeed]

Re: shift interrupter I THINK

Sounds like someone changed the distributor to the EST(good choice by the way) and changed how the shift interrupt works(original dist uses the ESA). Sounds like the shift interrupt switch is held closed. This can happen from a faulty switch, out of adjustment switch, or your lower shift cable is failing causing binding which keeps the switch engaged. My bet is on the last one.

Bruce, Its a 91 which came with EST ignition. So I dont think it was changed. I have had boat for many years and never changed anything I am pretty sure it was very much stock when I bought it 10 years ago.

 

[bruceb58]

Re: shift interrupter I THINK

Bruce, Its a 91 which came with EST ignition. So I dont think it was changed. I have had boat for many years and never changed anything I am pretty sure it was very much stock when I bought it 10 years ago.

You are correct. It does have the EST distributor and looks like it also has an ESA.

First thing I would do is still check the switch like I mentioned earlier.

If that looks ok, disconnect one of the wires from the switch to see if you still have the probelem.

If that doesn't work, unplug the ESA.

 

[justspeed]

Re: shift interrupter I THINK

How do you unhook a wire from one of the switches? They dont un-plug. other than the plug that they are both hooked too. I just finished re-wiring the ground hoping that was the issue. Going to test now. I will let you know

 

[bruceb58]

Re: shift interrupter I THINK

On past models you could do it. If there is a plug going to the switch, unplug it.

 

[justspeed]

Re: shift interrupter I THINK

Well guess what. Works now. Works just fine except now I need to figure out how to adjust a few things. I dont remember there ever being an issue with the rpms being lowered and it going into gear but its not right. Maybe because I have muffs on. You tell me.

I was just testing and now engine runs fine and when you go to shift the engine stumbles as it should but as you move shifter til its in gear the stumble stops before it goes into gear. Thats not good. I just tried a few times. RPMS go back up before you even get it close to in gear

 

[bruceb58]

Re: shift interrupter I THINK

If you are doing this on muffs, you shouldn't be getting any stumbling at all. The reason is that you have no load on your prop. The normal operation is that when you have a load on the prop and in gear it should stumble going out of gear because of the force on the dog gears holding them together. Going into neutral, wether in the water or on muffs should not activate the shift assist.

Since you have this problem on the muffs, its your lower shift cable that is binding. You need to replace your lower shift cable.

 

[justspeed]

Re: shift interrupter I THINK

huh Good info. I will have to look into this some more. I also will be testing boat on the water tomorrow so I will see what happens.

 

[justspeed]

Re: shift interrupter I THINK

Funny thing. I thought I had it fixed but I did not.

What I mean is I re-did the ground and tested at home and it was working again. I thought that was great. I launced boat yesterday morning and that was not the case.

I fired it up and all was well. I put it in gear and it died. I thought what the hell? I tried re-starting and it would not start. Turns out the interrupter was doing it again.

I unplugged from Dizzy and it fired right back up. To tell you the truth I dont see where I need it to start with. I had no issue changing gears yesterday while out on the water.

But today I will look at a few other things.