No spark from coil or points

[pilgrim32]

Hello All. Sorry I haven't posted anything in a long time. So here goes. I have a mercruiser 228hp GM305 with a mallory points ignition. I was able to get the old girl to start by adding fuel down the carb. But now I can't get any spark to ignite the fuel. Things I've replaced. Ignition switch,coil,points,condenser,cap,rotor also installed new battery. The motor has a 55amp circuit breaker next to the starter solinoid doesn,t seem to be tripped any thoughts out there of what to check next? With the key in the run position I have 10 volts at the starter and solinoid but only 5 volts at the positive side of the coil? Thanks in advance for any help.

[K4282]

if you have points (i recomend changing to electric) you have a white resister, check those connections and probably replace if needed, you can also bypass this to but dont leave it at 12v

[Cmount]

I have Chryslers, and I lost spark over the summer and had to change the ignition control module on one of the engines. I would also try just disconnecting the batteries and letting things sit for 15 seconds if there are no other items to re-hook back up. Because after it was all said and done, I did both and the second actually is when the engine came back to life. They are electronic ignition, so it may mean nothing to your issue.

[Big D]

....With the key in the run position I have 10 volts at the starter and solinoid but only 5 volts at the positive side of the coil?.....

You definitely have a low voltage issue, whether that is the only problem or not is the question. 5 volts to the coil is not enough. By-pass the resister as suggested and see what you have at the coil then. The problem is 10 volts at the starter is too low to begin with. Are you sure it is a known new fully charged battery? If so and you are familiar with a meter, perform a voltage drop test along both positive and negative wiring to see if you can find the culprit. Could be a bad connection like a wiring harness plug at the engine that is corroded or a bad connection elsewhere. Check that all your connections are clean, free of corrosion and tight including the ones at the starter and the battery. Also check the battery selector switch; everything in the circuit should be systematically checked. Also try disconnecting your tach wire at the coil and see if that makes a difference.

[pilgrim32]

Thanks all for the reply's. I will be investigating those thoughts this weekend. Resistor wire I can't seem to find it, I did remove tach wire at the coil no luck also I ran a hot wire from starter battery cable to positive side of the coil still no spark. I will be opening up the wiring harness and checking for bad wires. Yup the old girl has me stumped. I had her starting many times, but when the key switch sprank back to the start position to run position she would sputter and die. I have good fuel pressure at the carb so it had to be a spark problem that would stall her in the run position. Also found the neutral safety switch on the tranny has rotted off and if the two wire are not twisted together theres no power at all to the starter. Thanks again for the help.

[Big D]

......I ran a hot wire from starter battery cable to positive side of the coil still no spark......

did you connect this wire right at the starter or at the battery? I ask because you said earlier that you were only getting 10 volts at the starter. You should ensure you are jumping with 12 volts.

....when the key switch sprank back to the start position to run position she would sputter and die....stall her in the run position.....

Do you have a ballast resistor? Did you replace with an "external resistor required" coil, or one with an internal resistor? It will say on the coil and is dependent on whether you have a ballast resistor or not or a resistive wire to the coil. When you say you have no spark, are you sure the coil is not generating a spark or is it that you are just not seeing a spark at the spark plugs? and how old are the plugs?

Do you know how to use a meter and test voltage, continuity and resistance?

[pilgrim32]

Thanks Big D. The battery is brand new just a marine starting battery from walmart. I guess i will have to give it a charge to bring it up to 12 volts then retest voltage at starter and coil. The only meter I have is a automotive combo tach/dwell/volt meter. I was able to give the local NAPA parts supply company a mercruiser number for the coil and they were able to cross reference the number to one of thier marine coils and yes it says external resistor required on it. The plugs have been cleaned and don't look bad don't know how old they are? I have new ones just haven't put them in yet. Before this trouble started I could take the coil wire from the cap and ground it to the motor and you could see spark while cranking it over. Now nothing, I've had the boat for a few years and it was purchase as a fixer upper and boy does she need fixing! I was told the motor was seized so I filled the cylinders with PB blaster and let it sit,then filled the cylinders with marvel mystery oil hooked up a battery and she turned over. drained the mystery oil by removing all the plugs and cranking it over several time. Cleaned the plugs and reinstalled them then added fuel to the carb and got her to run until the fuel ran out of the carb. I hooked up a fuel supply to the carb now all she needs is spark. I am just trying to get her to run and idle a little just to see and hear if anything is knocking or rapping. Hoping to remove the engine this winter to break it down and repair/replace whats needed. She's been salt water cooled all her life so it should look pretty rusty inside her cooling passages. And yes electronic ignition is in her future. The hour meter shows she has 748 hrs on her so I hoping to get some more time out of her. So thanks again for the advise I 'll keep plugin along.

[Big D]

Do you have a ballast resistor?

Was the no park an existing problem before you replaced the points and condenser? Or did you replace them because she would not stay running with the key in the run position?

It’s not that hard to inadvertently short the points to ground so you never collapse the field in the primary windings of the coil thus inducing a high voltage in the secondary. It would be the same as the points not opening up. This is where a continuity check helps; with the points in the open position, you should get continuity to ground from one side of the points but not the other. If they both ground, that will not produce a spark. Could be the way the points are mounted, if they have a metal strip instead of a wire, ensure that it is not touching the distributor wall. Also ensure that the connecting bolt going through the side if the distributor is electrically isolated and is not shorting to ground. It should have a plastic sleeve to prevent this. You’ll also need to ensure that the primary high tension coil wire and at least one plug wire are actually good to check for whether the system is producing a spark.

[prowlersfish]

Have you checked the dwell ? This could give you a clue as to the points being stuck open or closed . Or if they are shorted to ground

[davidsmith]

pilgrim32 wrote:
....when the key switch sprank back to the start position to run position she would sputter and die....stall her in the run position.....

Have you checked the ignition switch. Just had to replace one for the same symptoms.

[Big D]

.....Have you checked the ignition switch.....

As noted above...

....Things I've replaced. Ignition switch,....

[K4282]

sputter and die is what my Silverton did when the ignition control module quit, totally out of no where, same as my Trojan, Chrysler 318

[9mtrojan]

I had the wire coming from the coil into the dist. and to the points arcking to the dist. housing. The insulation rubber cracked and it wasn't getting electric to the points. It was a rubber insert that goes aroung the wire and in the hole in the dist. housing. Drove me crazy.

[Commissionpoint]

I have the same engines as the OP. I ditched the old Mallory points jobbies for new Mallory YLM's. I was having similar issues getting good spark all the time. Lots of stalling at low revs. I couldn't friggin take it anymore so I got online to Summit and JEGS to see who had the best deals on YLM's. Summit had a deal on so thats where I ended up getting them. I think they were around 375 each. YLM624AV is the model to look for with these engines.

Completely plug and play installation. Came with nice pigtails to attach to ground and +12v which plugged right into the distributors. Took more effort to get the light out and time them after install than it did to drop them in. No more changing points, checking dwell, replacing condensors, etc. I also took the oppertunity to change out the AC plugs to NGK's. (Paul just had a mild infarction from reading that. ) The engines now both fire up very quickly, and run nice and smooth. (They were ok before, but better now.) If I have already run them that day, they ignite so quick on restart that folks have asked me when I repowered. I haven't. 1750 hrs and counting.

As for the 750 bux for the upgrade? I can't even fill my tanks for that. Money very well spent IMO.

[prowlersfish]

I love NGK plugs . They make me money . When I pull them out to get a GM engine running right .