Electronic ignition conversion

[codyandamber]

I just just put an electronic ignition on my 1985 351w. The boat ran perfect before, but the points were in need of replacing. After I put the kit in three things happened:<br /><br />1) There is now a slight hesitation when I start off slow. <br /><br />2) The tach is not correct. 36 mph and 2200 rpms now according to the tach. Of course, it is obvious it is running more rpms. <br /><br />3) It will not start when you are turning the motor over. I have to turn it over and let off the key and it will crank right up. <br /><br /><br />I added a coil with an internal resistor as required.<br /><br /><br />Any help would be greatly appreciated.

 

[elpaso]

Re: Electronic ignition conversion

If it will not start, until you release the key - something is wired wrong.<br />Turn key to run position - with a test light - you should have 12 volts at + side of coil.<br />Turn key to start position - with engine rolling over - you still should have 12 volts at + side of coil.<br />If not - check the wiring. <br /><br />On the back of most tachometers, there is a small adjusting screw.<br />With engine running, hook a rpm-drell meter to minus side of coil. <br />At any rpm, turn screw until both tachs. read the same. Turn screw very slowly.

 

[codyandamber]

Re: Electronic ignition conversion

Thanks for the help Elpaso. What I am not understanding is why it would start correctly before and not now. I only added the conversion it and the coil. The wiring is still the same.<br /><br />Also, how would this effect the Tach?

 

[Fishermark]

Re: Electronic ignition conversion

You need to bypass the resistor wire that fed your points. It lowers the voltage -- good for points, bad for electronic ignition. Simply splice into the wiring harness (not sure where on your boat) before the resistor wire. (It may be possible you have a ballast resistor instead of a resistor wire, but I doubt it. Regardless, you simply need a "switched" 12 volts to your module).

 

[codyandamber]

Re: Electronic ignition conversion

Fishermark, <br /><br />Will this correct my #3 problem, too? <br />I am going to check now about the resistor wir. I know there is no external resistor.<br />Thanks,<br />Cody

 

[codyandamber]

Re: Electronic ignition conversion

One more question, Fishermark. When you say "You need to bypass the resistor wire that fed your points" are you talking about the wire that runs from the coil to the points or from the ignition to the coil? When I added the elecronic ignition they had the wiring that runs from the distributor to the coil in it. It is not resistor wire.

 

[elpaso]

Re: Electronic ignition conversion

Fishermark is right - you may have a <br />resister - and a resistance coil, in<br />line to the distributor.<br />Lets start over - give us "all" information.<br />What ? engine-outdrive-year-electronic <br />ignition - wire color to what - everything ?<br />And still do the coil test that I asked.

 

[codyandamber]

Re: Electronic ignition conversion

It is a 1985 mastercraft with a PCM 351 inboard and Borg and wagner 1.1 tranny in it. <br /><br />Purple wire to -<br />Black to +<br />Gray from + to wiring harness and another from - to harness...(It is raining now and I can't check for sure)<br /><br />I just changed the coil to an internal resistor coil 3.7a<br />The coil I had before was about 1.9a, the instructions recommended at least 2.5a<br /><br />From the distributor to the coil there is not a resistor of anykind. I am not sure from the ignition to the coil. I will check that tomorrow .<br /><br /><br />Before I changed it over it ran perfectly, just needed points so I thought it was a good time to upgrade. It still runs great after it starts (startup has the one glitch but takes one try.) It just has the little hesitation when easing up to speed. Plus the tach is wrong.<br /><br />Thanks for your patience...

 

[Fishermark]

Re: Electronic ignition conversion

Yeah, it's the wire that runs from the wiring harness. On my dad's Mercruiser which I switched over to electronic ignition for him, the power came from the back of the alternator, then split from there to the automatic choke, and the resistor wire. (If you didn't know it, you would think it was just a regular wire). <br /><br />As to your problem #3, the fact that the problem only showed up after your conversion is a bit of a puzzle, because typically when you are starting, your ignition gets its power direct from the starter solenoid - a full 12 volts. I would suggest getting it set up as it should be as noted above and see if that solves the other problem.

 

[codyandamber]

Re: Electronic ignition conversion

Thanks for all the help. I remember seeing that gray wire from the alternator. It was all rolled in electrical tape, but I will check it to see how much resistance it has and change if need be. Is that 14 gaige wire?<br /><br /><br />Cody

 

[codyandamber]

Re: Electronic ignition conversion

I also wanted to ask what you mean by bypass? Can I not just run a regular 14 gauge wire in its place???<br /><br />Thanks

 

[elpaso]

Re: Electronic ignition conversion

Purple wires do not go to coil neg. With this old a boat, who knows how many hands have played with the wiring. If you have had problems such as burning up points, your wiring may have never<br />been correct. <br /><br />Start with basic wiring - sometimes it is easier to replace than to<br />diagnose and repair, old unknown wiring. <br />Your 12-volt feed to coil does not come from alternator or starter.<br />It comes from the key switch. There may be a resistor "wire" spliced<br />into this wire. You may never find it. <br /><br />Simple fix - With a helper to use key switch - and a test light - Remove all wires from coil - turn ignition switch on - find wire with<br />12 volts - ( should be purple ) block it off. - hit starter - find wire that<br />is only hot when starter is rolling engine - block it off - ( you do not<br />need this hot start, wire with electronic ignition ) It goes from key switch to neutral switch on transmission - and then to starter solenoid. <br /><br />Run new wire from key switch terminal marked - I- ( ignition ) to coil<br />plus. You have now removed any unknown resistance in original <br />wiring. And new coil with internal resistor will protect sensor. <br /><br />Wire new distributor to coil as factory recommends. At this point do<br />not hook up any other wires to coil. ( gray ? )<br /><br />Try to start engine - if it runs - touch gray wire to minus side of coil -<br />tack. should jump. If it does, stop engine - hook up wire. And adjust<br />screw on back of tack as explained earlier. The same setting on a<br />tack. will not read an electronic - and a point distributor.<br />Sometimes you have to replace tack. <br /><br />On an old inboard this should work - <br />5 minutes of thinking - can save hours - and dollars - good luck.