Spark from the coil but no spark at the plug

[Kenny224]

Hello all,
First timer here. I am the third owner of a 2002 240DA 305 MPI Bravo III I thought this would be a perfect project boat for me. In my mind it was really neglected and just needed a lot of TLC. Just about all the chrome was pitted inside and out, the interior had bad damp stains and the deck is badly sun beaten. The one thing that I did like about the boat was that the owner before me had a 3/4 engine installed (new block and heads) 2 seasons ago. I was told he ran the last one low on oil. Anyway to get to the point the marina that installed the engine was very sloppy. Didn’t run the wires the right way, some just hanging and some just not connected to anything. Last Sunday when getting ready to go out, she started up fine, I got her up to Temp. (170) I have a long "no wake zone" approx. 15 min of. I get out, hit the gas she starts moving and dies. We get towed back. ( thank you Sea Tow ) I check for spark, I have no spark at the end of the spark plug boot but when I pulled off the coil line it had spark? I pulled the cap off it looked good so did the rotor I even made sure that the rotor didn’t have play. What I did notice is in the back of the distributor it looks like some thing should be plugged in to it??? ( some thing for a Ignition module??? ) I looked and looked for any plug from the harness to be just hanging there but nada.. Any ideas????

Kenny.

_________________________________
2002 Sundancer 240 305 MPI B III
" My Problems " Lower New York, NY

 

[Captain Crispy]

If you have spark at the coil output which is not making it to the plug, then you should check the spark plug wires. Sounds like they are grounding out, or you have the wrong wires on it.

 

[JediJD]

The reason a distributor is called a distributor is that it "distributes" the spark from the coil. The coil is part of the primary circuit, and the plugwires are the secondary circuit. If you are getting spark from (as opposed to simply power to) the coil, then the distributor and secondary ignition system are worth a look. First...take the cap off and be sure the rotor is actually spinning when the engine is turning over.

If it is spinning, f you have an electronic ignition distributor, just pull the module (its a little electronic piece under the rotor) and take it in and replace it. You can test the damn things but they are about $15...try replacing it with a known good one.

 

[Lazy Daze]

Are you sure you're checking for spark at the plug correctly? In close enough contact with metal (engine)? It won't just park inside the plug unless you're completing the circuit.

If this is indeed what you did, don't take offense - I just wasn't sure based on what I read.

 

[Kenny224]

Hey Guys
When I tested for spark I did stick a screw driver in the boot and held it to one of the risers. I just don’t understand how I have spark coming from the end of the coil wire that’s going into the distributor but not at the end of the spark plug boot? I did try to spin the rotor by hand to see if any play was there but I didn’t try to crank it and look at the same time. I’m going down to the marina in a little bit and fart around again. As for an Ignition module do all Ignition systems need them??? Like I said, I see something that looks like one in the distributer housing but nothing is connected to it. There are no loose wires coming off the harness. Also if you try to look up the part number for an ignition module "www.selocmarine.com" it lists it as a sensor assembly ( not sold separately ) ?? One other thing... Would the coil still give off a spark if the ignition module was disconnect? I need help!!!

Kenny

 

[sprink56]

Good call on testing the spark but I'm guessing the distributor module. When I had an electronic distributor on my Formulas in the '80s I used to carry a spare.:thumbsup:

When you loose that module you are done...no warning..it just stops.

 

[Lazy Daze]

What's odd is it started up and ran fine in his driveway?

 

[sprink56]

What's odd is it started up and ran fine in his driveway?

I skipped over that part...:smt021...might be a "heat sensitive" coil...or module.:huh: These are fairly cheap things to replace...that need to be changed periodicaly any way.

 

[Lazy Daze]

I skipped over that part...:smt021...might be a "heat sensitive" coil...or module.:huh: These are fairly cheap things to replace...that need to be changed periodicaly any way.

But then we're back to.... how did it start up w/o the ignition module being plugged in? Ghosts? Gremlins? Maybe that last mechanic converted the engine to gerbil power? :huh: I'm totally at a loss for what's going on.

 

[Kenny224]

Hello All,
　
Well I’m back from the marina and the rotor is turning when I crank the engine. What I did notice is the spark from the coil wire was a orange color and not a sharp blue. Do you thing the coil is going and not strong enough to send a spark all the way to the plug??? I have a theory, I notice two or three weeks ago that the Mercathode system was disconnected. With the boat in the water all season I can’t see any of the zincs and all I can do is feel for the one by the prop. Of corse that one was missing. I replaced that one about two weeks ago and I check it tonight and it’s gone again. Does anyone think that Galvanic Corrosion started eating away at my coil?? I just don’t know what to think.

Kenny

 

[Kenny224]

Re: Spark from the coil but no spark at the plug **Update**

Hi All, ** Back With Update**
　
Well I ordered some parts. New Cap, Rotor & Coil all this stuff was kind of cheap and if it wasn’t the problem at least I know there are new parts on the engine. I am receiving major galvanic corrosion probably from a stray current in the area. I replaced zincs for a second time in two months and now I shut off the batteries and unplug from shore when not needed. All this has stopped the corrosion. I still worry what my drive is going to look like when I put it out for the winter. Anyways I replaced the coil and FYI on most MPI’s the ignition module is mounted on the same bracket as the coil, the one in the rotor housing is a dummy. I did get better spark from the coil but still didn’t start. I replaced the cap and rotor and boom she started right up. I was told that because I had a crab style distributer it would be possible the corrosion ate away at the metals in the cap sense it’s not a straight post connection... Sorry I didn’t post my update sooner but I’ve been out on the water alot lately.. And thanks for all the replies.. Kenny

 

[Hampton]

Excellent. Congrats. Thanks for closing the loop!

 

[Lazy Daze]

Thanks for the update, Kenny! Sorry I missed your update on 9/12. Good to know about the ignition module, too.

What type of anodes are you using? At least you know, they're doing their job! Look at it this way... if it was taking longer to wear them away, even more galv corrosion would be happening elsewhere... your drive and engine.

Did you get your Mercathode system working?

Depending on what your drive looks like, maybe you want to consider adding a secondary Mercathode? Or, maybe your anodes are doing their job and everything's fine. Be sure to remove props and check around the carrier bearing (the area beneath the forward edge of the forward prop).