Mercruiser Electronic Timing Advance Problem

[info@illuminationtech.com]

Bewildered by 1991 Mercruiser 3.0LX with Alpha 1 I/O unit. Has EST ignition system which stopped advancing one hot summer day. To get home, I set the advance manually by twisting the distributor. Engine ran fine at top end, but of course was hard to start.<br /><br />Replaced every component of this ignition system with new parts (except pickup coil) and the thing will still not automatically advance. Primary side voltages are proper, and I have actually replaced the ignition module twice (performs the electronic advance) when I thought that I might have zapped the new one.<br /><br />I set the timing at 6 deg BTDC at 750 rpm and the thing starts and purrs like a kitten. In the water it bogs at about 1800 rpm and the timing actually retards to about 4 deg BTDC. I can then rotate the distributor to about 24 deg and the thing runs like a bat out of hell all day as smooth as silk.<br /><br />Love the engine and am a fan of electronic ignition, but am about ready to pull the distributor and drop a new one in with points and condensor!<br /><br />Anybody had similar problems with this Mercruiser EST ignition - if so any knowledge would be of great benefit - Ia m out of mental capicity!<br /><br />Thanks in "advance" - no pun intended!

 

[12Footer]

Re: Mercruiser Electronic Timing Advance Problem

The only type i have had a wrench to are the old vacumm advance type.<br /><br />But even tho the timing actually retards, I would check the accilerator pump in the carb (if not fuel i8njected).<br />If it was out,it would "show" the advance an idle condition,even tho your pouring the coal to it.<br />Just a thinkin out-loud here, and may be way off base.

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

Wakemaster, you have 2 pluggs connecting to the distributor right below the dist cap....are they BOTH plugged in?

 

[Rex]

Re: Mercruiser Electronic Timing Advance Problem

YES THEY ARE PLUG IN.<br />WHAT GET ME WHY THE TIMING GO TO 4?<br />CHECK ALL WIRES AND HARDWARE.<br />HOW EASY IS IT TO TURN BY HAND?

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Thanks for the reply ODDD1. I am glad to find someone of your caliber to help. Not sure I can send big-******ed women via UPS, but succesful solution to this problem is certainly worth a case of LaBatts Blue longnecks.<br /><br />Yes, both connectors are plugged into the control module which is on the inside/bottom of the distributor. The connectors are push on type with neoprene like gaskets (not the Thunderbolt IV type with connector nuts).<br /><br />The first connector is a two wire connector, (red and purple)which comes from the coil. With ignition ON, both wires have 12V. There is a resistor in line with the red wire (6.8 ohms) and it drops about 1.0 volt.<br /><br />The second connector is a 5 pin version. The only active wire for this connector goes to the shift interupt switch for grounding the primary to make the shifts smooth. I know that this works properly because I just adjusted the shifting cables last week and manually ensured myself that the cut-off switch was working properly. There are two additional white wires that come from this 5-pin connector which are just flying leads that hang in space (female sockets neoprene jackets). I have no idea what they are for, and my manuals do not mkae mention of them. The other two position on this connector are not used.<br /><br />Sorry for the delayed reply - had the boat out for a long 4 day weekend and everything seems to work fine when I manaully advance to about 25 to 30 degrees. Just make starting and accelerating out of the hole less than desireable. More than anything, I hate a problem that I cannot lick!

 

[clanton]

Re: Mercruiser Electronic Timing Advance Problem

Do you have a book on this system? I dont but some of the systems had the advance in the dist pick up coil. and some had a knock sensor, which retarded the timing when spark knocking. May be only fuel injected engines. I just talked to a Tech that works at Merc dealer, he did not know about this engine. I will have a book next week.

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Thanks clanton - that is a great thought. My manual is very sketchy about this particular ignition system. I do remember reading in some book about some systems having a knock sensor - supposedly backs the timing up a couple of degrees once it "hears" pinging. I use high octane (94) and never hear any pinging, but perhaps the pickup coil is giving eroneous signals to the controller making it think that there is some pinging...<br /><br />I have kept from changing the pickup coil because I figured it was either good or bad and there was no "in between". Also to change this coil is a pain! The coil clearly sends signals to the ignition module because the spark is there - but maybe the quality of the signal is corrupted...<br /><br />Do you have any idea if the knock sensor is in the pickup coil, the ignition coil, or in the magnetic head assembly connected to the distributor rotor? Bottom line is that I might just be better off replacing the entire distributor assembly if the later is the case.

 

[clanton]

Re: Mercruiser Electronic Timing Advance Problem

No, but am going to buy Merc book, my next project is a V/6 mercruiser 1995 I think, a shop had it for 3 months still not runing owner ask me to give it a shot so I will pick a set of books.

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Great - will wait to hear from you if you learn more. I would gladly buy a manual that is specific to this ignition system, but have no idea if one exists. If you find one, please let me know the name and where to order it from.<br /><br />In principle this ignition system is probably great, but it is difficult to troubleshoot when not working properly. Ahh, long gone are the good old days of counterweights, points and dwell meters...<br /><br />Good luck with the V6 - I am interested in how you like it. Looking to upgrade boat size and power in a year or so. Like the gas mileage of the 4 banger, but.....more power, GRRRR!

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

Wakemaster, there is not detonation control on this system....proper name for system is a Delco EST....used on GM products for many years....confusion comes from the number of systems merc used on these motors...delco points, prestolite points,mercs own DDIS [digital distributorless ignition system] and delco EST....now, the reason I was askin about those plugs, the five pin that goes to the shifter switch..those 2 white wires have to be unhooked and NO power coming down that wire from the shift switch or the brainbox [module] will stick in 'service mode' and NOT advance the timing....next time you are in the boat, just pull that plug on the distrib and see if it advances with rpm....<br /> if none of this helps, you will need a new module in the distributor...

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

almost forgot, thanx for tryin on the girls, LOL the Labatts would do fine!

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Thanks ODDD1, that clears some things up. Yes it appears that Merc used a whole slew of different ignitions and I have been reading bits and pieces from books and on-line, but remained very confused. Thanks for the clarification - at least I finally know what I have!<br /><br />If there is no anti-knock then the only thing that seems like it could be the problem is the amplifier or the coil. Is the pickup coil "just a coil" then as first suspected? Meaning it either works or not?<br /><br />I pulled the 5 pin connector as you suggested and it makes no difference - and I have already replaced the amplifier twice now with no success. I got the parts new from NAPA - do you think that the Merc parts might somehow be be different?<br /><br />You also peaked my interest. What is the "service mode"? How does it work and what is it used for? What are the white wires for and how are they used? Do I need to put it into service mode for timing adjustments??<br /><br />Thanks for your continued help...

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

Ok, the pickup coil is just a coil..YES...<br /> next, NAPA parts...are the same? dont know....and wouldn't be using it in a boat anyway....amplifier has pre-programmed spark curve in it, unlike automotive closed loop 'feedback' systems....you getting same spark curve? I really doubt it.<br /> And finally, yes, you better be setting your spark timing in 'service mode' or your gonna be replacing a head gasket soon....service mode locks timing a specific setting so a normal timing light can be used to set initial timing...here is how ....run engine at idle, hook 2 wht wires together, provide 12v from shift cutout switch by manually engageing the switch...an then you can set timing...

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

again, didnt get all in my post.....your welcome, Wakemaster....its always enjoyable helping someone with more than fat between their ears...

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Well that would have been easy to figure out on my own! I guess that is why morons like us have to pay guys like you to keep us a float - go figure!<br /><br />Will try the service mode and set the timing again. Perhaps I have been so far off that the "pre-programmed" spark advance curve is off the map. Maybe all I've got is just a bad intial timing mark at idle. That would be a bonehead manueuver.<br /><br />NAPA carries Mercrusier parts now and the one (two) that I have purchased "claim" to be the same as the Merc parts...hmmmm.<br /><br />Really appreciate the help - will let you know how I fair this weekend which will be the first time that I get a chance to work on it. Taking my oldest daughter to college Thur/Fri - I am just not old enough for this.<br /><br />Upon successful completion you will have to give me a mailstop that accepts UPS shipments with glass containers!<br /><br />Incidentally, I spent a week at a cabin in lac du flambeau (?) in May for some fishing a decade or so ago. The mosquitoes literally picked the meat from my bones - they are like flying pirahnas up there!

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Hello again ODDD1. Thought I would give you an update as to what I accomplished this weekend. Put the ignition in service mode as you recommended. Appears to work as advertised (engine does not die when shift switch is activated)- but the timing mark does not move from the previous "non-service mode" position. It stays locked on the mechanical position first set, and refuses to advance with increasing RPM (when outside of service mode). Is there some magic way to exit service mode that I need to know about!?! Didn't really think so.<br /><br />Guess it can only be the ignition module, but am skeptical because I have replaced it twice. Is there some way that the advance section of the electronics can be zapped, while still functioning properly (providing spark)? Does the module need to be well grounded (there is thermal compound between the module and the base plate of the distributor)?<br /><br />Absent any further revalations, I guess I will order a new module from Mercruiser on-line and try again. Before I do so, is there another ignition system that you would recommend as superior to this one. I am at the point that I do not want to keep throwing good money after bad. If you had a strong recommendation for the DDS ignition system (or another) I would entertain dropping that one in. You have probably seen and worked on a few different types and have a preference. Your recommendation would be greatly appreciated.

 

[clanton]

Re: Mercruiser Electronic Timing Advance Problem

I still think the advance in the dist pickup coil.

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

Wakemaster, stick with what you got...is a durable system, the best alternative to points that Ihave seen yet....I pulled out my books today, the advance is built into the module, you should get 22* of electronic advance, if you dont, get a module. as far as tossin good money after bad, well, try a mercruiser part this time....

 

[info@illuminationtech.com]

Re: Mercruiser Electronic Timing Advance Problem

Thanks clanton and ODDD1 for your continued help. I will stick with the Delso EST as recommended. 22+6=28 which is about what I have been running as a hard set.<br /><br />It seems to me that the new module is sticking in service mode - and that has been on my brain since you mentioned it. I measured the voltage again at the red and purple wires and I get 12V on both. This does not make sense to me. One of them has got to be ground - and all the wiring diagrams shows the purple to be coil ground.<br /><br />Is it possible that I have a short (or leak) on the ground wire that is locking the module in service mode? Does this make any sense?<br /><br />What would happen if I ran a new wire from the module to ground (in place of the purple wire) for testing? I am ready to try this unless I am misreading the facts here.

 

[ODDD1]

Re: Mercruiser Electronic Timing Advance Problem

wakemaster, the coil has power to it all the time...it 'makes ground' through the module to intiate a spark...timing variation done by changing the coil 'grounded time'....it acts kinda like dwell on a points system....