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Still stalling

T

triton

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"Hello I have been dealing wit

"Hello I have been dealing with a stalling problem since last season. At this point I have narrowed the problem to ignition troubles.

I have: changed points, condenser, plugs, wires, dist. Cap, resistance wire.

During my previous posts these were some of the suggested replies in addition to fuel issues. Therefore I completely went over the fuel system, filters, tank p/u tubes, water in the gas, proper tank venting, fuel pressure etc even ran using auxiliary tanks – no change in performance. Recently, I double checked the for proper timing using a light, noticed the spark was sort of inconsistent this lead me to my concerns about my ignition system.

Currently I am not getting a spark from the ignition coil (it’s very hot). I would just change the coil but I’ve done that before while it was in “stall mode” with absolutely no better result i.e. the engine would start but once in gear it would cut off. So now my concern is why are the coils burning out? Am I using the proper coils for this engine…I did purchase them from a marine supplier. In addition, if this is a 12v coil which needs an external resistance wire, then why when the resistance wire is cold it allows 12v to the coil + terminal? These 12v are in addition to the 12 coming from the slave solenoid at start up/cranking… do you need both voltages for start up with a 12v coil? Once the motor has started the resistance wire reduces the voltage going to the + side of the coil to 6 volts the boat will run for apprx. 30 minutes and then shut down until cool off period ends. I think I’m burning out coils, but I don’t know why! HELP PLEASE!"
 
"What engine, carb and year?

"What engine, carb and year?

That is how a points ignition works. The coil gets 12 volts from the starter and when it disengagaes the resistor wire is supposed to provide 9 volts. Yours is only getting 6 volts. What is the voltage where the 12 volts meets the resistor wire?"
 
1976 formula 233c - mercruise

1976 formula 233c - mercruiser 351w - rochester 2 barrell carb.(rebuilt w/less than 20 hrs. due to stalling).The voltage at the choke (where the resistance wire meets thwe 12v) is 12.37.
 
"The voltage between the +

"The voltage between the + battery post and the + coil post should not drop more than 3.2 volts w/the points closed and the ignition on. Your voltage drop is nearly twice that amount. Carefully inspect the connections of the resistance wire at both ends for corrosion. Even if you think they are clean, use fine sand paper to polish them to reduce resistance and improve current flow. Do the same for the negative terminal of the coil.

If the voltage at the coil does not reach 8-9 volts then the resistance wire may be the problem."
 
"The voltage drop between the

"The voltage drop between the battery is not greater than 3.2 volts. When the ignition is on the voltage at the battery is about 12.8 volts, at the choke its down to 12.37 volts. Now after the new resistance wire heats up it reduces that 12.37 to 6 volts entering the positive side of the coil."
 
"The voltage between the &

"The voltage between the + battery post and the + coil post should not drop more than 3.2 volts w/the points closed and the ignition on. Your voltage drop is nearly twice that amount."

You just said it was 6 volts at the coil. That drop equals 6.8 volts. Connect a jumper from the battery to the + terminal on the coil and see if it will run w/o stalling.

If you don't have a points ignition coil then it will cook the coil every time because there isn't enough voltage to run it.

ANYONE; STEP IN IF YOU CARE.
 
"I apologize Guy, I misunderst

"I apologize Guy, I misunderstood your statement concerning where the 12 volts "meets" the resistance wire(at the choke). Yes the voltage from the choke through the resistance wire to the positive side of the coil there is nearly a 50% voltage drop when the engine is running.Yet with the ignition in the run position (engine not running)I get 12.37 at the positive side of the coil.

"If you don't have a points ignition coil then it will cook the coil every time because there isn't enough voltage to run it."

Is a "points ignition coil" different from a marine coil that needs a external resistor? Should I order a mercruiser OEM coil for this engine ? - It does seems like i'm frying coils like eggs
lol.gif
.

Thank you for your insight on my problem!"
 
No apology necessary.

"

No apology necessary.

"Yet with the ignition in the run position (engine not running)I get 12.37 at the positive side of the coil."

That's what it should be at that point for starting since the voltage comes from the starter circuit and switches to the resistor wire when running.

"Is a "points ignition coil" different from a marine coil that needs a external resistor?"
No; same.

Should I order a mercruiser OEM coil for this engine ?

First use the 12 volt jumper from the battery and bypass the resistor wire to the coil to see if it will run.
Did you get the correct resistor wire? Maybe that old model uses 6 volts for the coil. I always thought that 8-9 volts was required. In MHO 6 volts is too low for the coil to bump the spark up high enough to jump the plug gap.

I would investigate the OEM coil primary voltage requirement for that model ignition and get an coil if it requires 6 volts. If it needs 9 volts then I would probe the resistor wire in the middle until I found 9 volts and cut the wire there and attach it to the coil.
 
"Okay I changed both the coil

"Okay I changed both the coil and the points to a Pertronix II system. She started right up, ran good but overheated in fifteen minutes of run time? this is new. Cut off the engine, allowed to cool. Restarted - again ran good unless I tried to accelerate which would cause the carburetor to back fire and again much like the overheating this was new to my engine i.e. only started after the ignition change. But on the brighter side the engine ran continuously for over an hour smoothly unless I attempted to rapidly accelerate. Do I need to reset my timing? If so, what degree? Do I need to readjust the carburetor idle mixture? My instructions with the electronic point system did not mention any of these symptoms. In addition all this happened on muffs in the back yard!"
 
"did you feed the pertronix mo

"did you feed the pertronix module's red lead with the resistance wire? if YES, revisit those instructions.

On the old system, based on the above, I'd be inclined to think the resistor wire has gone bad. You could always add a ballast resistor in place of the wire, if needed.

The voltage at the coil with key on, engine off, will change with the points being open (higher voltage) or closed."
 
""Do I need to reset my ti

""Do I need to reset my timing? If so, what degree? Do I need to readjust the carburetor idle mixture?" Yes, 10 deg. BTDC"
 
"MAKOMARK, No more resistance

"MAKOMARK, No more resistance wire! 12v directly to the coil.


Guy, I will reset timing to 10-degree BTDC.and let you know what happens."
 
Will

The coil used for a po

Will

The coil used for a points ignition uses a external resistor

A coil for a HEI or electronic ignition such as the merc thunderbolt uses a internal resistor in the coil.

When converting to a pertronics ingintion and you use the original coil from the point ignition you should have the resistance wire or a ballst resistor in place so you do not over heat the coil.

If you purchase a aftermarket (pertronics coil) then you may be able to use 12 volts all the time.

Please specify EXCATLY what you have done and not done!!
 
I'm with kghost - re-estab

I'm with kghost - re-establish your baseline if the timing adjustment doesn't return things to "normal"
 
"Well... I reset the timing an

"Well... I reset the timing and now she purrs like a kitten, the timing had jumped back from 10* to near 0*.No more excessive heat or backfiring. I will launch this weekend weather permitting. Thanks guys for all your suggestions.

Wil"
 
"Kghost, I purchased both a ne

"Kghost, I purchased both a new coil(flame thrower II)which requires full time 12v, and a Ignitor II Electronic Ignition. The coil requires no external resistance wire as with my o.e.m. to decrease coil input voltage. This pertronix conversion system requires no external resistance wire."
 
Wil

Now that is how to rela

Wil

Now that is how to relay info to us for a correct understanding of your situation...........for once a good answer/response with a positive result!!
 
"Wil

One more thing, if all

"Wil

One more thing, if all goes well, this will be the LAST time you need to F**K with your ignition sytem again for many years and then only a cap rotor and plugs and wires when needed if needed but no more points and timing issues!!!"
 
"I couldn't wait till the

"I couldn't wait till the weekend,took off work thursday to lauch the boat. The boat performed great for over two hours before the crackle of thunder rushed us back to the launch. Stalling problem resolved...Thanks all!"
 
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