Ready to sink the flippin thing.......

[Smacken]

I have an 87 3.0 mercruiser with traditional ignition. I have replaced starter, coil twice, points, condenser, plugs and wires, still not getting a consistant spark through the distributer? Battery is new and working fine. Checked connections throughout the boat, All seem fine. Been out 4 times, each time ran like a dream for 1-2 hrs, come home to flush it and no go. everytime I tried something different and I seem to get it going, now it's pretty much decided it will not fire. Spark does come out when i connect plug to coil wire. Anyboby have anymore suggestions?

 

[jtmarten]

Re: Ready to sink the flippin thing.......

Check your shift interrupt switch. It may be sticky causing no/intermittent spark.

 

[Smacken]

Re: Ready to sink the flippin thing.......

I bypassed it to see if that was it. Didnt make a difference>

thx

 

[45Auto]

Re: Ready to sink the flippin thing.......

The only things that you didn't mention as being replaced are the rotor and distributer cap. If you are getting spark from the coil, the only place left to lose it before it gets to the plug is the coil wire, distributer cap, and rotor. At least one of them is bad.

 

[Smacken]

Re: Ready to sink the flippin thing.......

Yup, rotor and cap we're changed as well. Do you know what the options are for switching to electronic ignition? I'm a little concerned that someone might have put the wrong wires on at some point as I heard that using wires from an electronic ignition on a conventional one can cause simular problems. This is way too confusing as it doesn't get any easier than conventional ignition?

 

[79arabian]

Re: Ready to sink the flippin thing.......

Was coil getting overly hot? It could be the ballast resistor. I dont know if yours is internal or external but it is wort a look as they are cheap.
If the coil is getting to much juice it will run fine until it overheats then run like crap or just shut down completely.

 

[Smacken]

Re: Ready to sink the flippin thing.......

It is external, It has a resistor wire I believe. Doesn't appear to hot, but the wires get warm on the positive side.

 

[TheSheesh]

Re: Ready to sink the flippin thing.......

I had a similar problem last season. The boat would run like a champ for several hours. After sitting for a little while (eating lunch, etc.), I'd try to start it and no joy. It would crank all day and the voltage was there, but it just wouldn't start. Some helpful boaters needed to give us a tow. It happened again, but after a rest it was able to be restarted. Had the marina mechanic take it and do some diagnostics. $500 later and a new 'sensor' (a $40 part), and we took it out... and had the same problem. I was NOT happy.

Turns out it WAS the coil. I pulled the old one out and did a resistance test on it. It failed. What happens is the oil in the coil evaporates/burns off over time. The oil exists to cool the voltage step up wiring. It takes some time to overheat , and just like a car engine, the engine bay/coil will get a bit hotter after running since there is no airflow. Once it cools, you're back in business.... and confused.

 

[Smacken]

Re: Ready to sink the flippin thing.......

Thanks, I've never done the resistance test on the coil, I'm just assuming it is good cause it's new. Think i'll try that. My only difference is that even when it cools, It still wont start.

 

[Chaparralboater]

Re: Ready to sink the flippin thing.......

Car related but, my vette had the same symptoms and I threw parts and money at it adding to over a grand. And landed up being the ignition control module. (icm). Don't know if you or boats them self have them but I'm trying to help..sorry if what I said does nothing for you

 

[Doernuth]

Re: Ready to sink the flippin thing.......

Most of the electronic conversions I have seen use the original Distributor Cap, Rotor Button and wires, so no prob there. The conversion usually requires that the ballast resistor be removed from the system, at least mine did as the recomended coil has a built in resistor.

Also check the fuel system, your symptoms also sound like a vapor lock. As the engine gets hot the fuel vaporizes and the engine won't start, when it cools the fuel recondenses and your good to go.

Have you tried running the blower? You didn't mention it earlier. Move the air in the engine compartment, may do the trick.

 

[TheSheesh]

Re: Ready to sink the flippin thing.......

Thanks, I've never done the resistance test on the coil, I'm just assuming it is good cause it's new. Think i'll try that. My only difference is that even when it cools, It still wont start.

Ah, I missed that you replaced the coil TWICE. Hmm, so it doesn't start when cool, but when you throw a new part at it.... Weird one.

 

[6meter]

Re: Ready to sink the flippin thing.......

Remember one thing, new parts don't nessicarly mean good parts. How about a neutral switch? Go to the Adults Only sticky section. Determine correctly if fuel or ignition problem.

 

[bruceb58]

Re: Ready to sink the flippin thing.......

How about a neutral switch?

A neutral switch only prevents the starter from cranking.

1) What is the voltage at the coil with ignition on and points closed?

2) Are your spark plugs gapped properly? Too large a gap is harder on a coil.

 

[6meter]

Re: Ready to sink the flippin thing.......

Gotchya. I was just throwing anything out there and thinking with my mouth open.

 

[potatoe]

Re: Ready to sink the flippin thing.......

i had same problem and changed distributor and problem went away. but it could be anything, if its coming and going it could be as small as a bad or lose connection.

 

[Smacken]

Re: Ready to sink the flippin thing.......

Sorry for the extended absence as I have been away for a bit. Problem is fixed! Still not 100% sure what did it, but in checking the voltage coming out of the coil, it was running at 12.5 v at all times which means either I didn't have a resistor wire or the coil should have been a internal resistor. Fix was a $5.00 ballist resistor for a Dodge engine wired into the system. Figure I was burning out my plugs each time. Also had a small hole in the manifold so I think I was getting some water in the cylinders, and maybe fouling the plugs that way. Next thing I did was bought a 2004Campion 505s. Nice little boat (Canadian made) with 60 hrs on the 3.0 Merc! Other one is now for sale but at least in good running order. Thanks for everyones help on this.