Need help with timing 1987 90 inline 6

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Is it possible that the stator red, blue, red/white, blue/white wires are labeled backwards. What difference would it make which box they go on any way?

 

[daveswaves]

Re: Need help with timing 1987 90 inline 6

Is it possible that the stator red, blue, red/white, blue/white wires are labeled backwards. What difference would it make which box they go on any way?

Anything is possible and I have heard of incorrect colored wires however, it worked before......
All things being equal it should not matter which box fires which coils. In a running system that is. You have a system with an anomaly and somehow it is making a difference. I mentioned before about ground wires. It is important that each coil is grounded properly, each switch box is grounded properly, and the stator is grounded properly.

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Pull up a chair and get ready for the latest update. Today I was able to get the static timing set, but only by connecting #1 plug wire to a plug in a different cylinder. With The plug in #2 and #1 wire hooked up I was able to get both idle and WOT timing to work. So now I put the plug into #1 hole and I get spark and idle but not above. I move the plug and wire back to a different hole and it works.

Here is where it gets really strange, with the plug in #2 hole and #1 coil and wire connected to that plug it works, now just add a plug to #1 hole with out a wire, # 1 stops firing above idle. Remove the plug from #1 and it works again.


SOMEBODY PLEASE TELL ME THEY HAVE SEEN THIS BEFORE.

I think I am going nucking futs.

Why will it fire unless it is under compression?????

 

[daveswaves]

Re: Need help with timing 1987 90 inline 6

Glad you got the static timing set. I think what you are seeing is a couple of things ganging up on you.
1. Your timing light is not sensitive enough to pick up the spark properly, its OK when the plug is firing in air as there is more emf to pick up around the wire. Under compression the spark is somewhat weaker and perhaps your light just cannot pick it up. It is sparking but you don,t know it.
2. You could be cranking it too slow, the engine will be tight after the rebuild and you may not have enough rpm to carry the flywheel past TDC fast enough. The flywheel may "stall" momentarily. When you advance the throttle the flywheel simply is not there yet, it was held up or slowed down.

At this point if you are happy with the static timing I would double check all the connections and then run it on the hose, low speed, don,t rev it, just give it a chance to work out all the oil etc that is in there.

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Thanks Dave, your words are better then a strong cup of coffee, very soothing.

I did find that I had 5.8 volts on my kill circuit so I have a new switch on the way for that and two new switch boxes just to be safe.

So you are saying that the spark is effected by the compressed air around it, could you explain a little further.

 

[daveswaves]

Re: Need help with timing 1987 90 inline 6

Thanks Dave, your words are better then a strong cup of coffee, very soothing.

I did find that I had 5.8 volts on my kill circuit so I have a new switch on the way for that and two new switch boxes just to be safe.

So you are saying that the spark is effected by the compressed air around it, could you explain a little further.

Sure, air is a dielectric at atmospheric pressure. If the voltage is high enough the air will ionize creating a path for the charge to follow, hence the spark. Under compression the air is an even better dielectric (insulator) it takes more energy to create the ionization and then the spark. Thats the short answer.

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Dave I never thought about it that way but it kinda makes cents especially since there is no fuel in the combustion chamber.

Did some research as to where the 5.8 volts is coming from and found too many circuits tied together under the console. There is a seperate hot and neutral run fron the battery to the console for lights, gauges and etc. . . but for some reason the previous owner tied some neutrals into the ground wire from the engine and even one to the kill wire for the ignition which gives me voltage on the Black/yellow wire to the switch boxes. He was even using the red wire from the engine to power some of the circuits. I plan on splitting them and leaving just engine functions to be run off the red wire from the engine, ie.. start, and choke.

I was planning on a rewire job in the future but I guess the future is now. I have two new switch boxes and a new ignition switch on the way. Thanks for you help and encouragement.

Durwood

 

[daveswaves]

Re: Need help with timing 1987 90 inline 6

Dave I never thought about it that way but it kinda makes cents especially since there is no fuel in the combustion chamber.

Did some research as to where the 5.8 volts is coming from and found too many circuits tied together under the console. There is a seperate hot and neutral run fron the battery to the console for lights, gauges and etc. . . but for some reason the previous owner tied some neutrals into the ground wire from the engine and even one to the kill wire for the ignition which gives me voltage on the Black/yellow wire to the switch boxes. He was even using the red wire from the engine to power some of the circuits. I plan on splitting them and leaving just engine functions to be run off the red wire from the engine, ie.. start, and choke.

I was planning on a rewire job in the future but I guess the forture is now. I have two new switch boxes and a new ignition switch on the way. Thanks for you help and encouragement.

Durwood

You have solved a future problem if not part of your initial problem. Accessories must have their own supply and return. The wires back to the motor are not large enough to handle all the current that the total boat requires. Your ignition system was acting like the voltage was low, perhaps that was due to the wiring. Either way you have taken the steps to eliminate a long paddle back. Did you get the switchboxes from Wayne? Just curious.

 

[daveswaves]

Re: Need help with timing 1987 90 inline 6

Dave I never thought about it that way but it kinda makes cents especially since there is no fuel in the combustion chamber.



Durwood, actually its not because of the fuel, the same thing will happen with a completely dry cylinder. The air molecules are heavier under pressure, the heavier molecules require more energy to get them excited to the point where they release an electron to start the ionization process. Effectively raising the resistance of the air path. If the ignition system is weak you will not get current flow, no spark.

However, Once the electron IS released it does not like to be (loose) and it combines with another oxygen molecule, forming O3 (ozone) which conducts the electricity very well. The spark energy is then dissipated through the ionized air path. Ignition, Lots of other stuff happens as the fuel mixture ignites, resistance wise, but for this discussion we don,t care and the merc ignition does not care.

 

[tashasdaddy]

Re: Need help with timing 1987 90 inline 6

http://forums.iboats.com/showthread.php?t=168855

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Thanks Tashasdaddy, I was working from my shop manual which is almost word for word to that link.

Is there a way to make that link a sticky at the top of this forum since so many people seem to need the information contained in it. I see you are a Moderator, so any thing is possible, right?

Durwood

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

UPDATE:
Switch boxes check out good, Starter was turning over slow, tightened connections and recharged battery.

I pulled it out of the garage and hooked up the water hose and in about 5 minutes it was running for the first time after the rebuild. Sounds great, hitting on all 6 cylinders, but idling a little to high( 1300 rpms). Smoking more due to 25:1 oil ratio. Wired up a new hour meter and now have .6 hours on it.

Reading through the manual I am suppose to adjust the idle stop screw to lower the idle. My question is since the throttle cam is just barely touching the carb roller, if I back off the idle stop screw it appears the only thing I am doing is moving the timing. Is this correct?

How much gap between the throttle cam and carb roller is too much.

 

[turbinedoctor]

Re: Need help with timing 1987 90 inline 6

Bump