Shift interrupt switch

[smithrock]

Re: Shift interrupt switch

Don,

Here are some pics. of the Distributor, hopefully this helps. [sorry if they are a little blurry]
The writing says Pertronix where the black and red wires come out. What about replacing the cap with Thunder Bolt cap?

Thanks.

http://i173.photobucket.com/albums/w65/shelbyrae22/distributer001.jpg

http://i173.photobucket.com/albums/w65/shelbyrae22/distributer005.jpg

 

[Don S]

Re: Shift interrupt switch

That is exactly why I wanted to see inside the distributor. It is a Prestolite distributor, and the wires coming out are just like the BID system. Same color, same place. But the insides are Pertronix.
Might check with Pertronix on how to hook it up with the Mercruiser shift interrupt switch. http://www.pertronix.com/

You can get the cap and rotor from a Volvo 430 or 431 engine, or just check at NAPA and tell them you have a V6 with a Prestolite screw down cap. Take your old cap and rotor to be sure. Same with the plug wires. The Merc will not fit, different ends on the distributor end.

 

[smithrock]

Re: Shift interrupt switch

Okay, thank you very much! I'll try and contact them. Hopefully I'll just be able to wire it to the coil or something. I'm curious as to why it matters witch it's wired to if the distrbutor and the coil are both electrical sources?

Is the distributor that I have a good one?

watch for my new thread on my water/fuel separator.

 

[Don S]

Re: Shift interrupt switch

It's not as good as the merc Thunderbolt ign. The pertronix only replaces the points and condenser, but leaves the mechanical advance weights and springs under the plate the module is now mounted to.
It was probably used because it was a cheaper fix than what was wrong with the Thunderbolt.
You will probably find the black wire from the distributor will go to the - side of the coil, and then another wire will go to the shift interrupt switch in place of the white/green wire. But you are going to need the shift interrupt switch if you ever plan on getting the drive out of gear without shutting off the engine first.

 

[smithrock]

Re: Shift interrupt switch

Makes sense! now it's all coming together! Do you think that is possibly why I can't seem to get it in neutral either from forward or reverse when I'm out on the water? At home with muffs on -no problem. Maybe the switch is my problem and not my lower shift cable! Hopefully, I can get the switch working and then go from there as far as the cable concerned.

I want to "Thank you" for all your help and time you've put into my problem!

 

[Don S]

Re: Shift interrupt switch

Do you think that is possibly why I can't seem to get it in neutral either from forward or reverse when I'm out on the water?

I don't THINK it is, I KNOW it is.

I want to "Thank you" for all your help and time you've put into my problem!

Hang in there, you ain't done yet.

 

[smithrock]

Re: Shift interrupt switch

I don't THINK it is, I KNOW it is.



Hang in there, you ain't done yet.

I know, I know

 

[smithrock]

Re: Shift interrupt switch

Don-

I'm having trouble trying to get a hold of anyone in tech support with Pertronix, hopefully they will call back. If you have any ideas let me know.

 

[smithrock]

Re: Shift interrupt switch

Well, the guy from Pertronix called me back and he basically has "no idea" on where the white/green wire should go, says he needs a wiring diagram. He did say the black wire goes to the - on the coil.

He did say it doesn't need the diodes like on the OMC's though. So I just need to find out out where to connect the white/green wire. He mentioned something about maybe connecting to the tach? but that doesn't sound right to me.

Don, looks like I still need your help on this one!

 

[Don S]

Re: Shift interrupt switch

In the drawing above, the white/green wire will now go from the terminal block to the negative side of the coil.
Your distributor wires will still be red to + terminal on the coil and black to the - terminal on the coil.
The ground wires (black) on the otherside of the terminal block will hook up the same and will also ground in the shift plate.

 

[smithrock]

Re: Shift interrupt switch

Okay, so the black wire will JUST hook to the shift plate NOT to the coil at all. White/green just to the -side of the coil. Correct?

 

[Don S]

Re: Shift interrupt switch

Hang in there, I screwed up! be back in a bit with some more info.

 

[Don S]

Re: Shift interrupt switch

Normally, when I get into one of these kinds of threads the first thing I do is verify engine SN to make sure of the year........... Well I didn't, and it came back to Bite My Azz.
Seems you have an 84, not an 85. The 85 is probably the boat year, but it has an 84 engine package. Happens all the time since engines and boats have differnt manufacture dates, and manufactures tend to use the old engines in newer boats if they have some left over.
Anyway, turns out Merc used the Prestolite distributor in 83 and 84 on their 3.8L engine. (didn't know merc ever used the 3.8 till today)
Click here and have a look at the 185 (4 BBL.) GM 229 V-6 1983-1984 listing. It also gives you part numbers to use for conversion to Sierra parts if you want.
Now, the wiring, here is the wiriring diagram for the 3.8 with the prestolite diagram you have. Your distributor has 2 wires coming out of it instead of the single wire as shown in the drawing.
Your red and black wires coming from the distributor will go to the + and - terminals on the coil. The rest of the wiring on the diagram stays as is.

 

[smithrock]

Re: Shift interrupt switch

Okay, so you were basically right, white/green converts to grey and goes to the -terminal on the coil, black goes to black wire that goes to wiring harness-correct?

Thanks for the update on my engine--I had no idea:

I was also told that I have a 4.3L V6 not a 3.8, maybe when it was rebuilt the went up to a 4.3, does that seem logical?

Seems I'm missing a SS screw that monts the terminal block to the shift plate, looks like I'm headed to the hardware store!

 

[Don S]

Re: Shift interrupt switch

I was also told that I have a 4.3L V6 not a 3.8

People selling boats don't always tell the whole truth, and may have said 4.3 because they didn't know there was such a thing as a 3.8. Or it was replaced by a 4.3 longblock and all the accessories just changed over from a 3.8. Hard to say what.
Now, if you look just below the gasket surface on the forward starboard head, on the block there is a pad with a stamped engine number in it. That will tell the story if it's Merc. There should also be some block numbers cast in the block that will tell you what it is.

 

[smithrock]

Re: Shift interrupt switch

Don,
I got this number from the back of the block just above the firing order GM14095286 ( does that tell you anything?)

I'll look for the other numbers tomorrow,

Quick question: When I connect the black wire to the harness, there are 2 black wires one looks to be either a 12 or 14 gauge and the other looks to be a 6 gauge. I am assuming I splice and connect to the 12 gauge, correct?

 

[Don S]

Re: Shift interrupt switch

I didn't have any info on the casting numbers for a V6, only V8's so couldn't help you there. Here is a link to the Merc service bulletin with some numbers you can check.
http://www.boatfix.com/merc/Bullet/97/97_06.pdf

Quick question: When I connect the black wire to the harness, there are 2 black wires one looks to be either a 12 or 14 gauge and the other looks to be a 6 gauge. I am assuming I splice and connect to the 12 gauge, correct?

You shouldn't have anything over 16ga in the wiring you have to do for the shift interrupt switch.
Here is how you need to wire it. I wouldn't use any of the existing engine harness wires if you are not sure of them or where they go.
Just make a gray or whatever color wire long enough to go from the switch terminal block to the coil and another for ground. Like this.

 

[smithrock]

Re: Shift interrupt switch

Well, I wired it all up correctly and tested the switch with the muffs on and the motor running-- IT WORKS
So I installed new recirculation pump, shift interrupt switch, water/fuel separator and took apart my carb to clean it. So far everything seems to be working ! The real test will be out on the water--tomorrow!

THANK YOU DON !

I really appreciate ALL the help and for seeing me through this !

 

[smithrock]

Re: Shift interrupt switch

Don,

Took it out on the water today, the switch worked fine EXCEPT shifting from neutral into reverse at low rpm's (such as taking it off the trailer or backing from a stand still) it stalls everytime. A couple times at low rpm's shifting from forward into neutral it stalled. Now if I shift quick from forward into reverse it works. But I'm not always able to shift forward first. Any ideas?

Also, if you could can you take a look at my new thread- Temp rising?

 

[Don S]

Re: Shift interrupt switch

You probably have a bad lower shift cable. Replace it, follow the instructions for adjustment to the letter and it will probably work. When the cable starts corroding and getting stiff, it holds the shift interrup switch on to long causing it to stall. Probably why it was disconnected to begin with.