No spark 1986 150 mercury

[elbob54]

New stator. Have checked all wiring and grounds. Has a 2 wire Volt/reg and Rectifier. Plus it has a Idle Stab/advance Module.

 

[Maxz695]

Re: No spark 1986 150 mercury

disconnect the pigtail on the engine and then see if you get spark. Could be bad key switch or throttle saftey switch as well as a lanyard kill switch worn lanyard key or disconnected

 

[CharlieB]

Re: No spark 1986 150 mercury

Disconnect the Black wire w/yellow trace line that connects the ignition switchboxes to the engine wiring harness then retest for spark. This is the 'Ground-to-Kill' wire, any short to ground in the wiring, ignition switch or lanyard switch will kill all spark.

Second, cranking speed, minimum 300 RPM for the stator to generate sufficient voltage for the ignition to function. Poor battery, cable connections, starter brushes, all eventually reduce cranking speed until the ignition fails to fire.

Lastly, that Idle stabilizer module, discontinued by Merc. Remove it, they ground the Bias to advance timing to maintain idle speed, when they go bad and advance timing indiscriminately they cause rods to come out the side of the block.

 

[elbob54]

Re: No spark 1986 150 mercury

Disconnect the Black wire w/yellow trace line that connects the ignition switchboxes to the engine wiring harness then retest for spark. This is the 'Ground-to-Kill' wire, any short to ground in the wiring, ignition switch or lanyard switch will kill all spark.

Second, cranking speed, minimum 300 RPM for the stator to generate sufficient voltage for the ignition to function. Poor battery, cable connections, starter brushes, all eventually reduce cranking speed until the ignition fails to fire.

Lastly, that Idle stabilizer module, discontinued by Merc. Remove it, they ground the Bias to advance timing to maintain idle speed, when they go bad and advance timing indiscriminately they cause rods to come out the side of the block.

I bought this motor from a fellow that said his friend had tried to (hot wire it) as he put it?? prior to the loss of spark. He was told that the stator was burnt up now, so he replace it with a NEW one. Still no spark. The motor over all looks great for a 1986. The compression is 120 in all cylinders. Lower unit fluid clear of metal and not milky. Trim up trim down works great. I figured this ol boy still has some life left. This is all I know about the motor.

My first thoughts was switch boxes since the stator is new. However I want to first rule out broken or burnt wires and bad grounds. Secondly I wonder about the Volt/Reg or Rectifier. The Idle Stab is going to be trashed but I wonder if being hooked up right now, could it be bad and some how stilling my spark?

Is there a way to by pass everthing but Stator, Trigger and switch boxes just to see if the boxes are working? V/R Bob

 

[CharlieB]

Re: No spark 1986 150 mercury

Disconnect the Black wire with the thin Yellow trace line that connects the switchboxes to the engine wiring harness, now test for spark.

This wire is the 'Ground-to-Kill' wire, grounding this kills spark.

If someone 'hotwired' this motor he may have connected 12V to this wire at the ignition switch and fried both switchboxes.

The ignition switch is actually two seperate switches within the one case. The ignition side simply connects the B/Y wire to the solid B ground wire to kill spark.

The remainder of the ignition switch handles the 12V system to power accy's.

While the B/Y is disconnected and your are checking for spark, also check that B/Y on the motor harness side for any voltage with the ign switch turned on and again off. ANY voltage found then replace the ignition switch with the correct new switch and repeat the test just to be sure.

 

[elbob54]

Re: No spark 1986 150 mercury

Disconnect the Black wire with the thin Yellow trace line that connects the switchboxes to the engine wiring harness, now test for spark.

This wire is the 'Ground-to-Kill' wire, grounding this kills spark.

If someone 'hotwired' this motor he may have connected 12V to this wire at the ignition switch and fried both switchboxes.

The ignition switch is actually two seperate switches within the one case. The ignition side simply connects the B/Y wire to the solid B ground wire to kill spark.

The remainder of the ignition switch handles the 12V system to power accy's.

While the B/Y is disconnected and your are checking for spark, also check that B/Y on the motor harness side for any voltage with the ign switch turned on and again off. ANY voltage found then replace the ignition switch with the correct new switch and repeat the test just to be sure.

Stator and tricker wires coming from fly wheel. This is where the fire begins.. Now, can I directly hook these wires or wire that will cause the Switch Box to fire, if of course the box is good and if it don't fire then I can determine it's bad. I'm talking, By-passing Rec/voltage reg and ignition switch.. harness disconnected. This is a shade tree mechanic approach I know, but is it doable? I could hire someone to check all this and I may end up doing so, but I'm trying to figure this out without the use of meters. What do you think charlieB V/R Bob

 

[Maxz695]

Re: No spark 1986 150 mercury

One thing thst I found out today is, and this was off the wall. The plastic connector that joins the carbs together be it 2 or 3 carbs. (Made a carb to replace and when istalling the shaft fell out of the lower carb)> Ingeniuous. If the plastic clip breaks only one carb will open. You will get spark and it won,t start The way to cure is to replace the joining connector from top to bottom or if more than 2 carbs the broken unit and everything should be hunky dory. Not saying this is your problem but it a thing to look for. Check to see all buterflies are opening at the time of throttle advance even under full choke. If you have no spark which is what you must find out first then I would think stator or switchbox. being No spark could be either of the 2. With no meters and manual it might be imposible to tell which. Being a 150 HP there are probably 2 switchboxes and for both to go bad is rare. I would only assume JMO The stator is dead

 

[CharlieB]

Re: No spark 1986 150 mercury

If there is no spark with the B/Y wire disconnected you CANNOT ASSUME the switchboxes are bad, yet.

First make sure the cranking RPM is at least 300 RPM.

Second, you will need a DVA Meter or a DVA Adaptor to use with any Volt/Ohm meter to test the output of the stator and triggers, if ALL DVA tests are acceptable only then can you rule the switchboxes bad, otherwise it is a crapshoot buying NON-returnable electrical parts before PROVING which parts is at fault.

Third, you still need to test the B/Y wire at the ignition switch to make SURE it never has voltage whenever the switch is turned, otherwise it WILL destroy your new switchboxes.

 

[elbob54]

Re: No spark 1986 150 mercury

Thanks Charlie, for all your help. I'm going to get someone with the equipment and the know how to read these components V/R Bob