Points 1976 150hp

[BugF]

Hey guys mercury 150 inline 6 s/n - 4754200. Ok now have intermitting fire, New Dist. cap , plugs, switchbox , Ing. coil, internal and boat side wiring harness. Have not had a compression test yet, fella comming out Wed to do one. My question is does this motor have points? When I try to crank it it will just spin over but as I release the key or even just bump the key it wants to fire. Fella said it sounded like the points bad. Just dont recall seeing any points on the Motor. Oh heard it was bad luck not to have named the boat, So I go in the morning to pick up the new name " SHORE BEATS WORKING " Dont know bout that though working on the motor been full time job. Thanks for any help.

 

[wired247]

Re: Points 1976 150hp

Yeah, theres no points. That switch box "amplifies" the signal from the Variable Reluctance Transducer ( everyone calls them hall effect sensors but the '76 is actually a VRT. There is a difference ) . The VRT is located inside the distributor and is triggered by that plate that travels around under the rotor. Think of the switch box as a big transistor or electronic switch that is triggered by the VRT and then runs the switched signal through a capacitor set and on out to the coil to fire the spark plug.

 

[BugF]

Re: Points 1976 150hp

Any Idea next move for issue with intermitting fire ? Got Boat mech headed out wed. to look it over but have done all the work so far myself and just tryin to get a heads up on what may be the issue. Just hope it aint Dist. 2012 prices for 1976 parts are a shinny pennie.

 

[wired247]

Re: Points 1976 150hp

When you changed the switch box what did you change it with? New to you or CDI new? Could be out of time, could be a bad ignition switch. What you are describing sounds like a bad ignition transducer. The CDI Unit is an actual hall effect switch and they are quite rugged.

FWIW CDI sells a new distributor trigger for about $200 ( black bear ) .


If you want to save a little I know where you can pick up a complete working distributor for about $100.

 

[Chris1956]

Re: Points 1976 150hp

Wired, While researching for another post, I noticed the '72 850 Mercs had what appeared to be a reluctor-based ignition. it had a 4 lobed reluctor and a pickup, where the timing disk usually is. I looked around a bit, but that was the only model I saw that had that ign system.

 

[wired247]

Re: Points 1976 150hp

Wired, While researching for another post, I noticed the '72 850 Mercs had what appeared to be a reluctor-based ignition. it had a 4 lobed reluctor and a pickup, where the timing disk usually is. I looked around a bit, but that was the only model I saw that had that ign system.

The pickup is built into the ignition pickup housing and is triggered off the slots in the bronze plate. Sure as sh!t, Its a VR pickup. You can see it clear as day on an oscilloscope but you don't need that. Just spin the shaft on the distributor. If it spins freely its a Hall effect. If it pauses at each signal trip its a VRT. Keep in mind that while Hall effect pickups for ignition use have only been in use since Bosch pioneered them in the late 70's. Mercury used VRT pickups in the Thunderbolt system just like every other transistorized distributor system made by every other US vehicle manufacturer in the 70's. VRT's are still in use today.

FWIW you get a better low speed signal with a VRT.

 

[Faztbullet]

Re: Points 1976 150hp

You have no points and the problem you describe is a sure sign of a bad trigger assy

 

[BugF]

Re: Points 1976 150hp

Thanks guys well not much left it could have been. Mech. will be here Wed to look at it with experenced eyes, guess I've done as much as I can with just a test light and carb cleaner. Gonna do a little research on Trigger prices, Thanks again guys, I can prob bet wont be last question I come up with. But been a good learnning experince for me.

 

[wired247]

Re: Points 1976 150hp

Gonna do a little research on Trigger prices,

Cough Cough. Black Bear Sporting Goods. Cough Cough.

 

[BugF]

Re: Points 1976 150hp

Got ya ! Have already ordered some stuff from them. Real pleased with shipping and workable with price. Thanks Update after Wed.

 

[BugF]

Re: Points 1976 150hp

Ok just an update on firing issue. Boat Mech came today right off the bat he found a almost broken wire and where sombody had alredy tried to patch the issue on the stator. Said the two wires from stator 1 for charging and the other sending voltage to the switchbox So Stator ordered . Please everybody keep ya fingers crossed for me !!! like my very first post " Almost brand New 1976 Mercury". I think this is the complete orginal problem Just over looked the condition of the wires from stator to the little connecting " Block" what ever that little peice is, Wires from there to rectifer are new, Just didnt look close enough. Oh and pulled Pontoon out today also fixing to start on it, it's got a 65 hp Mercury on it, I know what to look for now !!! Thanks guys for all your help, will try and update with pictures after get stator installed.

 

[wired247]

Re: Points 1976 150hp

Thats not really what those do. Its an alternating current stator running into a rectifier to change it to DC. The DC charges the battery and powers the ignition although the inline mercs will run just fine with the stator completely unhooked until the battery dies. Both wires go to the rectifier. Neither feed the switch box directly.

 

[Faztbullet]

Re: Points 1976 150hp

As Wired posted , the stator has nothing to do with ignition on your model...you might look for someone who has a little better knowledge of that battery ignition system as the fellow you have does not.

Fella said it sounded like the points bad.

Said the two wires from stator 1 for charging and the other sending voltage to the switchbox

 

[merc850]

Re: Points 1976 150hp

Here's the wiring to help clarify what goes where

 

[BugF]

Re: Points 1976 150hp

Ok you guys brought me back to earth, thought that had to be it. Well broken stator wire needs to be replaced anyway I guess . Well last thing on the motor that has not been changed is the Dist. housing and spark wires. with season comming close to an end guess I put in line at local boat shop for once over. Thanks guys, Wish iboats had an annual area meeting where you could have "Show and Tell" sure would make life better for us novice old Mercury owners.