Mercruiser 888 Mallory YLM Electronic Distributor No Spark

[Gerbs686]

I recently purchased a pair of the YLM512 distributors for my 1976 Wellcraft Nova. I?ve got twin 302 (rebuilt Mercrusier 888), and decided to upgrade to the electronic distributors. I installed them last weekend and was unable to get the engines to turn over. After diagnosing the entire electrical system with a marine tech, we were able to find that the coil is not discharging ? there is no spark coming from the coil. We used a multimeter to ensure all grounds were good, the coil was getting ample voltage, and did just about every trick in the book to diagnose and isolate the issue.

I?ve double checked and ensure that the engine is properly wired against the wiring diagram in the Service Manual #2, and can verify that the engines ran last year prior to putting it in storage (winterized the engines last fall with the old points style distributors).

I?ve heard from some boaters out there that while these distributors are a direct drop in replacement, there is sometimes the requirement to modify the wiring associated with the shift interrupter switch. The issue is on both engines, so I?m leaning towards a wiring issue before jumping to conclusions that I?ve got bad parts. Wondering what the possible solutions are, and if there is a way to check and see if the distributors are faulty.

Thanks for the help!

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

the dist`s are bad or hooked up improperly. the 2 wires from the dist go to the coil. thats it.
could reinstall a old dist for testing.

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Thanks - that's what I'm hoping against (figured it wasn't the case being they are both not working). Checking the wiring on the distributor to the coil - its simple red/green and ground (and hooked up correctly). I've got the old distros and will give that a try this weekend to ensure its not another problem somewhere in the wiring.

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Remember K.I.S.S If it Ain`t Broke.......................
The batteries were disconnected first, right?
points are the easiest to service and replace .screwdriver and matchbook.
will function perfectly to over 9000rpm.NASCAR used them for years, J boats too. Everybody wants nothing to do with their toys but turn the key. They refuse to learn how to service them or operate them or even start them. Some don`t even know what points or a carb look like.
Unless your goning to carry a spare module or Ignitor your getting towed .most likely by a boat that has a points ignition.
Boat Safe.

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Yea- batteries were disconnected. I agree with the KISS theory, but I was having issues with the old distributors, and decided that after 36 years they were to be replaced. While I appreciate the replies, I'm looking for some advice on how to diagnose or if there is something I'm missing. Maybe someone else has used the same set up and run into issues.

Yes - I want it to be turn key, but the difference here is I built the engines and know them in and out. I'm not some run of the mill weekend boater. I take great pride, just as everyone else out there does, when it comes to my boat.

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

using the 3 wire diagram is pretty easy. I would begin by verifying you have 12v at the + side of the coil and that the brown wire is hooked to a good ground.These optical or magnetic?

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Its magnetic. I checked, and have 12v at the + side of the coil, and a good ground to the engine. Just cant seem to get the coil to discharge - not sure if its the distributor not sending the signal/breaking the phase, or if its something in the wiring.

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Is the rotor turning? red to power, brown to ground, green to - coil

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

yes to all - Rotor turns, red to power (+ side of coil), green to negative (- side of coil) and brown is grounded to engine block. checked ohms on the ground to confirm its a good ground.

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

All i can suggest is using jumpers ,hook the old dist up to the coil and spin it with your fingers to verify coil output.
black wire to coil - and ground the dist body.If coil now sparks then the module is bad in the new dist.

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Just got a response from Mallory:

Stan, Apr 29 16:18 (EDT):
Thanks for the email. Some of these require modification and some do not. If you use a meter on the negative side of the coil and turn it over you will see if it is being triggered. If you don't have a trigger signal on the negative side, then you probably need to view the shift assist file I attached to the email. Let us know if you have any further questions.

I've attached the diagram they are referring to - has anyone seen this modification or ever made it? Success?

 

[Bt Doctur]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

yours grounds out the neg side of the coil to aid in shifting. if that switch is bad or if its activated it will ground the - side of the coil and no spark will be produced.did the old dist make spark in the above post??

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Haven't had a chance to check it - did all the work this weekend, working now (gotta make the $ to spend on the boat!). I also talked to Summit Racing about the issue, and just to be safe they are sending me a new set of distro/coils (great customer service!). So, to be safe, I'm going to first check if the old distro makes spark when plugged in as you've suggested, then check the negative side of the coil when trying to crank, and if all else fails I'll then swap to the new/replacements parts. IF I get the same outcome (which for some reason I feel will be the case) - I'll have those parts on hand from radio shack to make the improvised switch.

AND at the end of all of this, if it still fails to fire - its back to good ole points!

 

[haulnazz15]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

If it's any consolation, the Pertronix billet distributor (uses Ignitor II) and Flamethrower II coil have been flawless and simple to install/set up on my 351w. Only two wires to hook up, no points/gap to set, auto shutoff even if you leave the key "on". Just a thought if you can't sort out your issue with the Mallory setup.

 

[FreeBeeTony]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Aren't those PDF files refering to an OMC ESA system?
Does that apply to a Mercruiser also?

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

I've used Pertronix in the past, and had little to no issues with them - but I only used the conversion kits (replacing the points/condensers), not the whole distributor. I'll research those a bit more if this continues to go south. At the end of the day, I'm not looking for earth shattering performance, the motors are only putting out around 225-250 ea, I'm just looking for reliability and some decent econ (oxymoron with boating, right?!).

Freebee- I asked Prestolite (the tech help that provided that response for Mallory) if that makes a difference. I think there is a difference, as I only have a black wire (tach) going to the negative side of the coil. I've done some more research, and from forums and testing, it looks as if its either the modules in the distributors, or there is an issue with the coil. As I was able to manually discharge the coil - I think I've isolated it back to the distributors. Although, when I put the multimeter on the green (negative) wire coming from the distributor and turned the engine, I could observe the phasing in the circuit - there appeared to be a signal going back to the coil, so with that I'm scratching my head.

 

[dgg190]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

I have this exact engine old merc 888 and I put in a YL512CV dist in a few years back (wow just checked it was 6 years ago). It was drop in for me other than getting a very good ground. I had issues with this and in fact wired the ground from the dist directly to the engine within a foot. Once I did this all my problems went away. Even though the multi meter said y existing ground was fine.

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

dgg - thanks for the info! What exactly do you mean wired "directly to the engine within a foot"? I'm pretty sure I have a good ground - its grounded to the engine as well (checked with multimeter like you said). I'll try switching the ground to maybe a better spot.

Wish I had other good news, but after going out this evening to grab the old distributors I noticed I had a TON of fuel in the bilge. at least 5 gallons +. After draining and venting and ensuring I had no electronics anywhere on the boat hooked up or otherwise, I took the cover off the fuel tank (wooden flooring), and believe I've isolated it to somewhere on the starboard side near the aft. Doesn't matter where - just I now know its going to come out and be replaced. Will be starting a new thread - possibly piggy backing off of : http://forums.iboats.com/boat-restoration-building-hull-repair/removing-fuel-tank-528013.html

going to be a long spring...short season this year - ah the joys in owning an older boat! I'm just very thankful I found this now, and had the distributor problems preventing me from getting in the water last weekend. possibly avoided some HUGE issues out on the water. Everything happens for a reason -

 

[dgg190]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

I think I responded to you PM, but couldn't figure out how to add a picture.

I originally connected the ground form the dist to a wire that went to one of my connect boxes that had a number of ground connected in it. This didn't work even though my Multi meter said the ground was fine. I then routed the ground wire directly to a bolt on engine, i.e. gave it its own ground.



In the bottom left corner you can see a yellow wire connector. This is the ground from the dist.

 

[Gerbs686]

Re: Mercruiser 888 Mallory YLM Electronic Distributor No Spark

Thanks Dgg- that was exactly it. Had to bolt the ground directly to the engine block. I ended up pulling a bolt from the water pump and put it there. Ran it for about 3 hours up river last weekend- runs perfectly. Starts without pumping gas or having to crank on the engine, and idles spot on.