spark problems in a converted electronic distributor.

[geiger1374]

ok guys this one is really got me boggled. i'm running a 305 chevy/merc 898 engine. origanally points but the owner before me installed a mallory electronic distributor. for some reason i can start when cold, and i can run on idle forever but when i get it up to speed and it heats up i have 1-3 min before i loose spark and the boat dies. i have changed coils and the external resistor going to the coil. same results everytime. i have also tried changing the coil with an aftermarket coil with and internal resistor. same results. i was out yesterday and it happend again. so i switched the hot coil with a cold one still no spark. and voltage is getting to the coil so its not that. my only guess from here is something in the distributor. but its brand new about a year old with about 10 hours. so i don't know. any help would be greatly appriciated.

 

[Maclin]

Re: spark problems in a converted electronic distributor.

I am not sure of the model of Mallory you are running, but it could the module inside the distributor. I know several car guys that ran Mallory Unilites and carried spare unilite modules with them as they tended to go out often and strand them.

 

[jomamma1]

Re: spark problems in a converted electronic distributor.

Geiger, leaving the key in the run position(for extended periods) can harm electronic ignition parts. I carry a spare ignition module in my boat for that very reason. JG

 

[Coors]

Re: spark problems in a converted electronic distributor.

My engine came with points, and I keep it simple.
Spare set in tool kit.

 

[MikDee]

Re: spark problems in a converted electronic distributor.

You did say an electronic distributor, right? I've never seen an electronic distributor that needed a resistor? (this is used only to keep the ignition points from burning up prematurely) You don't have points anymore, right? If so, then, another thing is, the ignition wire on your boat normally is a resistor scrap it, and run a full 12volts wire to the coil, for an elect. dist.

Going into your coil you also have a 12Volt wire activated by your starter to provde a full 12volts only for cranking, don't remove this. On the outgoing side of your coil, is usually your Tach, & Dist. wire.

Also, somewhere in here maybe extra wires for your momentary kill switch for shifting into gear.

 

[Don S]

Re: spark problems in a converted electronic distributor.

You did say an electronic distributor, right? I've never seen an electronic distributor that needed a resistor? (this is used only to keep the ignition points from burning up prematurely) You don't have points anymore, right? If so, then, another thing is, the ignition wire on your boat normally is a resistor scrap it, and run a full 12volts wire to the coil, for an elect. dist.

Haven't looked at Mallory and Pertronix have you. They do use the resistor wire.

 

[thumpar]

Re: spark problems in a converted electronic distributor.

Haven't looked at Mallory and Pertronix have you. They do use the resistor wire.

My Pertronix ignition only uses the resistor wire with the stock coil. I switched to a Pertronix coil that does not use the resistor wire, so I guess it depends on the coil used. The Pertronix that I bought was the ignitor II so that if I want to leave the ignition on it won't burn up the module.

 

[Maclin]

Re: spark problems in a converted electronic distributor.

+1 for Don S response.......It is the coil that determines whether or not ballast is required, not the type of trigger.

 

[Maclin]

Re: spark problems in a converted electronic distributor.

What Thumpar said too

 

[MikDee]

Re: spark problems in a converted electronic distributor.

Haven't looked at Mallory and Pertronix have you. They do use the resistor wire.

geiger, I apologize if I steered you wrong here, I concede to a more knowledgable, experienced, authority, Don :redface: I'm glad he's here to offer his expertise when needed

 

[fixb52s]

Re: spark problems in a converted electronic distributor.

Electronic ignition modules do go bad. The first indication of this is wnen they die when they get hot. That is what yours is doing.​

 

[Zero Balance]

Re: spark problems in a converted electronic distributor.

What was your reason for the conversion? What type of conversion kit did you use?
I too switched over to Mallory conversion ("Unilite") on my older V8 a couple seasons ago. To date I have had no issues however many years ago I ran this same system in a pickup truck that displayed the shut down/no spark scenario you described. It was not the modual as it was tested and found to be fine. I even replaced it anyways to no avail. I ended up replacing the distributor as the "plates" or something or rather were bad. I would recomend trying another distributor (possibly a used one) and see if the problem continues. At least if you run without failure on another distributor you may isolate your problem. I realize that a marine distributor may be recomended however (although many may object) using the gasket in an automotive dist. temporarily under troubleshooting conditions may give you the information you need. You can probably get one at the junk yard or borrow a donor from an old motor.

When I purchased my conversion I was told it was not the unilite module however when it arrived I was a bit dismayed as I never trusted that sytem. I carry a spare module in case of failure and like I say have had no problems so far.

 

[geiger1374]

Re: spark problems in a converted electronic distributor.

thanks guys. i've posted a new thread on this with more info. sinceit is still not working. check it out if you think you can help.