1990 3.0 Mercruiser ignition -no spark

[buzkill]

I have a 1990 3.0 Merc with a conventional prestolite ignition that will not start. I had replaced all tune up components (points,cap,plugs, etc.) 3 weeks ago. Boat was running fine until the other day when I was messing with the temp sending unit and gauges and think I must have screwed something up. I checked the voltage at the coil and get 7.5V. I understand that it has the purple resistive wire to reduce the voltage but what is the white block resistor for between the distributor and the neg side of coil? Also I checked the coil's primary and secondary resistance which seems to be in spec. Under the dist cap everything looks normal. Any ideas?...was thinking about gutting the points and installing the pertronix electronic kit.

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

what is the white block resistor for between the distributor and the neg side of coil?

There shouldn't be anything in the wire between the negative side of the coil and the distributor.<br />Look at page 4E-2 in the link below.<br /><br /> http://www.boatfix.com/merc/Servmanl/13/13E4R2.PDF

 

[buzkill]

Re: 1990 3.0 Mercruiser ignition -no spark

Thanks Don, that's what my manual showed as well, however there is a black wire that comes out of the distributor and goes thru this 1 ohm resistor. I bought the boat last November and it appears as if its always been there. The ign coil is a borg warner and it states on the outside "use with external resistor". Is that refering to this white 1 ohm resistor or does it mean use with the purple resistive wire?

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

No, that is not where a ballast resistor goes.<br />It's time for a picture of what you are trying to explain. <br />It very well could be hooked up all wrong. Hard to say without being able to see anything.

 

[buzkill]

Re: 1990 3.0 Mercruiser ignition -no spark

I can work on getting a picture over to you if that will help. Everything is wired just like the diagram you referenced except add the 1 ohm resister in line with the black wire going to the neg side of coil. I can't find anywhere in my manual that mentions the resistor and I'm not terribly familiar with a conventional ign system. Do you think it would hurt anything to try and run it without the resistor? <br /><br />Thanks

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

It's not supposed to be there, so what could it hurt.

 

[Mile-High Mariner]

Re: 1990 3.0 Mercruiser ignition -no spark

Buzkill - do you really have a 1990 Mercruiser with breaker points ignition? I was under the impression that Mercruiser had dropped the points-type ignition by 1990 and started using the DDIS and Delco EST ignitions in the 3.0s. I do know that they subsequently ditched the DDIS in favor of the EST, and now all 3.0s are running only the Delco EST HEI ignition system (I know Don will correct me, here, if I'm wrong).<br /><br />Maybe 1990 was the transition year. If you continue to have problems with your breaker points ignition, you could do like a number of forum members have done and convert to the EST ignition with no trouble at all.

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

You're right Mile High, 89 was the last year of points. I just assumed he has a 1990 boat with an 89 engine/drive package which is quite common since GM's model year changes don't coenside with boat model year changes.<br />And engine SN will verify.

 

[buzkill]

Re: 1990 3.0 Mercruiser ignition -no spark

Yes it is a 1990 model. Here is the engine S/N 0D377494. David, I was wondering just that if I could upgrade the system. What all would be involved in upgrading to the EST ignition?

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

Here is the new parts you would need. I put the Merc list price on each. <br />New distributor ($308), new coil ($85), small wiring harness between the distributor and coil ($12), and the main wiring harness ($271) so you have the proper ends to go on the new style coil, new plug wires ($33) and spark plugs.

 

[Mile-High Mariner]

Re: 1990 3.0 Mercruiser ignition -no spark

Don, my faith in your knowledge of things marine is constantly reinforced! <br /><br />Buz - Don's the man. If you intend to keep your boat for awhile, I would invest in the EST upgrade. Then again, I'm currently involved in a major reman/upgrade project on my Merc 3.0L that some guys would call silly, so $700 worth of upgraded ignition doesn't seem that bad to me. On the other hand, the bullet-proof reliability of the EST ignition is why GM uses it so broadly and why it made the cut when Mercruiser decided to use just one ignition system for the 3.0L and various V8 motors. Don't know why they don't use it on the V6 (Thunderbolt IV), but they do.

 

[buzkill]

Re: 1990 3.0 Mercruiser ignition -no spark

Yea, I agree Don's not human! I have searched previous posts the guy is always right on. I appreciate all the input that both of you have provided, I may have to put off the EST upgrade until after the summer season. But would definitely do it. I'm gonna work on her tonight and may go ahead and replace the points and condenser if I don't see anything else wrong. What is your all's take on the pertronix kit? Is that anything worth considering?

 

[Don S]

Re: 1990 3.0 Mercruiser ignition -no spark

I'm not super human, or a Borg, all this is nothing more than years of experience.<br />The #1 reason for a "BOAT" engine that has points in the ignition, to not have spark is because of the points. They get glazed over after sitting for a few months and being exposed to the marine enviornment. Get rid of that "resistor" in the neg. coil wire and hook it up properly.<br />A boat with a conventional points ignition should have a COMPLETE tuneup every spring before first launch, after a proper winterization the previouse fall.<br />Of course if that happened, it would be real dead here at the iboats forums.

 

[Mile-High Mariner]

Re: 1990 3.0 Mercruiser ignition -no spark

And a picture of Don comes a bit more into focus: he is a closet Trekkie (TNG, nonetheless!). And, don't worry, Don - I, for one, don't think you're any more or less than human. Borg, cyborg and androids don't get annoyed at the retarded things people do and say! <br /><br />Okay, Buz - get those dang points squared away and make a note to get rid of them at the end of this boating season. To answer your question, I don't think I've heard much bashing of the Pertronix system around here, so knock yourself out.

 

[buzkill]

Re: 1990 3.0 Mercruiser ignition -no spark

Don, you are right again. I checked the points which I had just replaced about 4 weeks ago and found the breaker arm is shorting over to the breaker plate at the pivot shaft. The insulation between the 2 is pretty poor. I'll replace those. I do have another question regarding the external ballast resistor that is on the neg side of my coil. With the resistor in place I get about 8 volts at the + side of coil, without the resistor in place I get 6.5 volts. Does that sound about right? I checked the purple resistive wire and get 1.5 ohms....Thanks