1973 85 hp Merc,, Lost spark while idleing

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

The 2 yellow wires that leave the rectifier and go under the flywheel were in horrible shape,,, once repaired with silicone and black tape, I'm about to replace them with new,,

silly me,, I didnt pay attention to what yellow went to witch terminal,, both are yellow wires and connect to yello terminals,, does it matter?

 

[Wingedwheel]

Re: 1973 85 hp Merc,, Lost spark while idleing

Looking at my wiring diagrams, it shows two yellow wires going to the two outside leads on the rectifier, with a red wire in the center. Hope that helps

 

[Chris1956]

Re: 1973 85 hp Merc,, Lost spark while idleing

The stator wires do not have anything to do with the ign on that motor. Sorry. They connect to a full wave rectifier and serve to charge the battery. It doesn't matter what AC terminals on the rectifier they attach to.

You need to run the distributor ign test. Look on the CDI Electronics.com web site or in the FAQ on this forum. it will tell you if your coil and switchbox is OK.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Cris,, from your statment ,, even if the two yellows are contacting each other
it in no way effects the running of the motor,, just wont charge the battery
Correct?

I'll check out the links you proposed

Thanks!

ussskydvr has a different thought of it affecting the running of the motor

see above^^^^^^

 

[Moody Blue]

Re: 1973 85 hp Merc,, Lost spark while idleing

Stator has one purpose, and that is to charge the battery. Is not directly related to the ignition system. The battery is what is needed to run the ignition system. Does not matter which yellow wire connects to which yellow terminal. There is one (+) terminal marked on the rectifier and that should be connected to a red wire to the battery.

When you pulled the plugs and turned the engine over, were the plugs grounded?

You really need to perform the switchbox test as mentioned in an earlier post. That will determine if the switchbox or trigger may be at fault. You WILL need either a voltmeter or a test light to determine if you have the required +12V on the appropriate switchbox terminals. Without the +12V, you will not get spark.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Hey guys,, I'm still in trouble, but I have a thought. My 1st car was a 65 mustang,, next was a galaxy both had silinoids like the one on my merc.
I could hotwire both from the silinoid to eliminate the ignition switch I remember running a wire from the positive post to one of the smaller wires,, run a screwdriver accross the pos to a small terminal and i was off and running.

Could I do that with my merc?

 

[Chris1956]

Re: 1973 85 hp Merc,, Lost spark while idleing

Yes you may hotwire it, however, you need to do a bit more. Put a jumper wire from the red wire on the switchbox, to the white (non-distributor) wire next to it on the switchbox. Now you will have bypassed the voltage from the ign switch. Now use a jumper from the red heavy wire on the starter solenoid to the small yellow wire on the solenoid. That will crank the motor.

USSkydiver wants you to disconnect the mercury switch. The mercury switch kills the spark if the motor is tilted too high. If you still have one, it will be right above the switchbox, on the distributor side. They are blue plastic, about the size of a large tootsie roll candy, and have one wire grounded and the other runs to the switchbox. Disconnect it.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

using a 12 volt light,, I have full time power to the red,, power to the white when key is on. This is on the switchbox.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

the green plastic base of switchbox connection has two cracks in it. I asume its to insolate the threaded stud coming out,, problem? also switchbox makes noise when I make contact with white wire when key is on

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Looks like maybe you all lost interest in this thread, but heres an update for any that havent

I replaced the switchbox,, rectifier, all bad wires,, roter spins while turning engine. I tried a diff set of controls,, same problem

When I have the plugs out,, but in plugwires and grounded I get a sharp spark on 1 plug when I turn on the key if i rotate the flywheel a lil, I'll get a spark on a different plug,, please dont give up on me fellas,,

The stater is my only hope and only thing I can think of any more thoughts
?

Thanks guys!

 

[usskydvr]

Re: 1973 85 hp Merc,, Lost spark while idleing

Ok, so now you are getting spark. Where is the timing mark when you get spark on the #1 plug? (with the throttle fully open to the throttle stop)

 

[trihull59]

Re: 1973 85 hp Merc,, Lost spark while idleing

this just happened to my same exact motor it was the switch box sadly they are extremely costly new or used, the coils on those engines dont go bad often what does often go bad is either the trigger or the switch box the switch box is behind that plate on the front of the motor with all those wires hooked up , the trigger is underneath the distributor cap

 

[asm_]

Re: 1973 85 hp Merc,, Lost spark while idleing

I just got done working on a 1974 85HP and can probably help. However, this is my second attempt of trying to understand your description. Frankly, I'm still not quite sure what you are saying.

When I have the plugs out,, but in plugwires and grounded I get a sharp spark on 1 plug when I turn on the key if i rotate the flywheel a lil, I'll get a spark on a different plug,, please dont give up on me fellas,,

Did the above statement mean you got spark on number one cylinder or spark on one cylinder?

B

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Thanks for responding USS..#1 plug sparks in the white zone of the timing marks. I just noticed,, with key on,, When i wiggle the quick connect, I get my spark.. though i repaired all wires going to it,, seems there is a short inside the rubber molding on the male side of the quick connect I now have a good source of old merc parts on the cheep, so i'll exchange that tomorrow and let ya know how it works out.

Thanks again

Doug

BTW my local boat shop wanted 540.00 for the switchbox,,460.00 for the stater. I paid 40 for the switchbox.

 

[asm_]

Re: 1973 85 hp Merc,, Lost spark while idleing

Not sure what a "quick connect" is, but I'm guessing you are may be referring to the wire harness with thick cable attached to the side of the engine. If wiggling produce any respond from motor, you have a lose connection there. For harness this old (40 years) it's not uncommon to have lose contact. You can replace the entire harness or see if it's possible to use needle nose piler to squeeze the female end.

BTW my local boat shop wanted 540.00 for the switchbox,,460.00 for the stater. I paid 40 for the switchbox.

Same around my area, the dealers in town are our high price and low inventory leader.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Morning guys! just got up ,having my java and checking this thread.

Thanks for responding ASM
What I'm trying to get across in my post is,,
I get spark to the right plug depending where the flywheel is at the time.
With key in on position,,and only when I wiggle the quick connect.
I know its the male side that has the problem, because I tried a different set of controls on the female side. Im about 85-95 % sure this is my problem.

I'll let you all know how it works out this afternoon

Thanks guys!! your support means the world to me!

Doug

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

Another question fellas,,,once i get motor running,,,can I use a maint free car battery along with my deep cycle battery pos to pos,, neg to neg,, or will the maint free battery screw things up?

 

[asm_]

Re: 1973 85 hp Merc,, Lost spark while idleing

Another question fellas,,,once i get motor running,,,can I use a maint free car battery along with my deep cycle battery pos to pos,, neg to neg,, or will the maint free battery screw things up?

When running two batteries in parallel, it's very much recommended that both battery to be the same type, same capacity and same age. This is every battery have different internal resistance, which will contribute to un-even load between the two batteries. Making sure the two batteries are the same will minimize this problem.

Now, if you are only doing this for the purpose of testing, you'll be fine as long as the cable between the two batteries are thick enough.

 

[nomorefords]

Re: 1973 85 hp Merc,, Lost spark while idleing

ok guys, this is what i did yesterday,

Knowing I had a bad male side of the quick connect and knowing if I could find one, and it would cost me $1,000 , 3 cows, and my 1st born child, I decided to wire direct.I took out the motor side (male),, cut off boat side (female) ,,striped back rubber coating, put new terminal connectors on all color coded wires and attached them to the following places

thick red---+ side of silnoid
thick black---Grounded to bolt on bottom pan of engine cover
grey--- Electric choke
brown---- brown contact on switchbox
small black----right side of silnoid
2 sm whites, not sure if it makes a dif but,
1 white to white contact on switchbox
2nd---- to left side of silnoid
Small red to red contact of rectifer,
then I ran a wire from that to the red on the switchbox, as my existing wiring had a union in the red with main wire going to red switchbox and the splice going to pos on rectifer.

I did however end up with an extra wire ( I'm going to call it peach color) Dont know where that might go. As there is no peach coming out of the male side of the plug.

Boys,,, I cant tell ya how excited I was to have licked this problem.
I hook up the battery,, turn the key,, and nothing,,zilch,,, nadda

last question,,,Bullet,,hanging,,jump off building,,,play on the freeway???

Haha just kidding!!!

yes,, battery has full charge

Can someone please go through my wiring to see if i missed something?

Note: I do have power to main pos and neg

Thanks guys! 1973 850 merc 3746584

 

[usskydvr]

Re: 1973 85 hp Merc,, Lost spark while idleing

thick red---+ side of silnoid OK
thick black---Grounded to bolt on bottom pan of engine cover OK
grey--- Electric choke OK
brown---- brown contact on switchbox OK (Not the side that goes to the Dist)
small black----right side of silnoid (side closest to the RED wire)
2 sm whites, not sure if it makes a dif but,
1 white to white contact on switchbox OK
2nd---- to left side of silnoid (should only have 1 white)
Small red to red contact of rectifer,
then I ran a wire from that to the red on the switchbox, as my existing wiring had a union in the red with main wire going to red switchbox and the splice going to pos on rectifer. OK

I did however end up with an extra wire ( I'm going to call it peach color) Dont know where that might go. As there is no peach coming out of the male side of the plug.
You should have a yellow wire that goes to the solenoid (on the same side that goes to the starter)

See attached pic