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B112
USA
5230 Posts |
 Posted - 04/26/2010 : 07:05:04
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| Charles, excellent! Thanks for contributing those links. |
Michael |
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richardpoconnor
1 Posts |
Posted - 05/14/2011 : 21:24:21
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I need help. Here's the situation:
My Mercruiser ECM went south.
My Mercury ECM Part #861926T3 no longer available. My unit was built by Delphi Automotive Services, Kokomo, IN with part number 16236999 it has a bar code 833999KA00037571 (I think the first 8 digits are model, the last 8 are the serial number for this unit).
My ECM runs a Mercruiser 5.7 EFI (MEFI-3), 350 cubic inch, 310 hp, GM engine (Chevy 8 cylinder converted by Mercury for marine use). The boat is a 2000 Searay 26’ Sundancer, so the ECM dates back to 2000.
Problem:
Engine starts right up, runs perfectly for hours. After shutting down engine, it will start right up again, then immediately stall. It will continue to start right up then immediately stall until I give up. If I wait couple hours (I assume when the ECM cools off), it starts right up and runs perfectly. My good mechanic thought it might be faulty ignition coil, but that checked out OK. He then noticed when he ran diagnostics on the engine, there were no reported faults, but the engine hours reported by the ECM would add an hour of engine run time for every ten minutes of actual time. Mechanic called Mercury who said I had a bad ECM (stalling and goofy engine hours) and needed a new one for $2,660! The original ECM (861926T3) is no longer available (it use to cost $1,500), replaced by new unit with a conversion harness kit for older boats. Replacement unit Part #892798A01 with conversion kit from Mercury costs $2,660!
My first option is to find a competent, daring techy who will open up my unit and see if “cleaning” it (or whatever they do) will give it a couple more years of life. I know ECMs can be “re-built” and/or re-programmed, but none of the companies I called will work on a marine ECM (but it is a GM engine). I don’t know how to get info on re-programming it, but I’m hoping that it might be just a bad connection that could be soldered or cleaned.
My second option is to find a used one on EBay. I have looked but none being sold now. One was sold on Ebay couple years ago for $450! Does anybody have a Mercury Part #861926T3, also know as Delphi 1623699? Will a Delphi 16237009 which looks identical to mine (Mercruiser MEFI-3 for a 1999 Mercruiser GM 502 Vortec Gen VI Mercury engine), or similar ECMs, work on my engine?
My last option is to buy new ECM for $2,660 …. bummer, or just quit boating.
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B112
USA
5230 Posts |
Posted - 05/15/2011 : 15:22:19
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I'm going to suggest more testing of the ECM you have. I actually have two ECM's one I am going to reprogram (already matched my program) and the other is the orginal which I will not touch (it will be my constant or control). I eventually may disect one to see what the circuit boards are, but I probably will never get that time.
Before you gave up boating, you may just consider a carb. Though everyone tells me the reliability of the electronic ignition is much better and that's why I am staying with it. My engine dyno guy when we ran my engine generated more HP/Torque with a carb and was insisting for me to switch to a carb. |
Michael |
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got2boat
5 Posts |
Posted - 03/27/2012 : 17:08:52
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I'm not getting spark for ignition and my mechanic tells me he thinks it's the MEFI-3 ECM. It's a 1999 5.7 EFI for a bravo3.
Is there anything else to test? I found this a SB on a sensor failure here www.boatfix.com/merc/bullet/99/99_04.PDF
Any ideas on fix would be appreciated.
Still looking hard for a replacement.
We have only found new a mefi4 kit that is supposed to work, but is crazy expensive. |
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B112
USA
5230 Posts |
Posted - 03/27/2012 : 22:04:24
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My mechanic years ago diagnosed this as a bad computer. He was wrong. I had a bad wire going to my distributor which was intermittent. I setup my harness and tested every wire on a test bed. I'd suggest tracing back from the plugs to the computer any parts which can be bad and replace those first.
Look at the Red/Black, Tan/Black and White wires. They are probably these three(but I am not sure - I need to look at my harness or another manual):
J1-3 Ignition Control (Ref. Low)
J1-10 Ignition Control Signal
J1-24 Ignition Control Bypass
Those would have electronic drivers in that computer which would control the distributor. Don't put a meter on those what ever you do unless the repair manual tells you you can. You don't want to burn the driver circuit in the computer. Check those wires from the computer when it's disconnected all the way to your distributor for breaks and if it's not connected to the computer use a ohm meter to check for breaks.
Your problem can be in the distributor, the coil, the computer or in the wires. That's it. I'd bet against it being your computer and look at swapping out the cheaper parts and check the wires first. Good luck and let me know what you find.
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got2boat
5 Posts |
Posted - 03/30/2012 : 17:08:56
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quote:
Originally posted by B112
Your problem can be in the distributor, the coil, the computer or in the wires.
The distributor and coil were replaced already because they were cheap, including a little sensor that was inside.
The mechanic says that the wires can't be replaced, that they can only be purchased as part of an upgrade with a Mefi4 kit. I think I'll try the multimeter on the wires myself, do you have a link to a manual, or a video? I'm hoping that the colors are consistent on the wires at least.
I'm assuming "no user serviceable parts inside" for the mefi3.
Is there ever an issue with cleaning the contacts, bent contacts?
Thanks for all the help.
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B112
USA
5230 Posts |
Posted - 03/30/2012 : 21:06:14
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| Got2Boat, I was reading my Service Manual which is for the 502EFI. Chart 7 is the Ignition System Check. The complete test does not seem to ever point to the ECM being bad. From my short read of this test, I believe the computer reads the distributor voltages as a sensor input to the computer program. I don't believe you need the ECM to generate a spark or time the engine. I believe the only control the ECM has on the timing/spark is the ability to advance the distributor. Thus, I don't think your ECM is preventing a spark in your system. Now your ECM does control when your injectors inject gas, how long these are open. So if your ECM was bad, you would not be getting gas in your cylinders. It would not be a spark problem. The tests of your engine are detailed and in the manual. While I don't have your manual, you can order it from Mercury and you'll have your exact engine tests. Let me know what your mechanic says. I also know that they can call Mercury and Mercury will help with the diagnosis (only if they are a true Mercury dealer). I had a mechanic contact Mercury with me on the phone and we diagnosed my engine. My biggest problem was an intermittent loose connection on my distributor circuit. After that was solved, my engine was extremely reliable, except for a leak down problem which has since been solved. Hope this helps, let me know what you find. |
Michael |
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B112
USA
5230 Posts |
Posted - 03/30/2012 : 21:25:58
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quote:
Originally posted by got2boat
1) do you have a link to a manual, or a video?
2) I'm assuming "no user serviceable parts inside" for the mefi3.
3) Is there ever an issue with cleaning the contacts, bent contacts?
To answer your questions directly:
1= I don't have an electronic link to a manual for your engine. A while back Mercury left their technical website open and someone published a link to all their manuals, I never found the time to download them which a friend recommended. His thought was that maybe one day I'd buy another Mercury. I will take a different approach to boating.
2= No the MEFI is hardened and you can't service it. I'd bet your ECM is fine, though we'll find out.
3= I personally have not had a connector problem, but I did find two bad wires in my harness. One was the wire going to my distributor (engine stalled) and the other was a sender wire (temperature sender pinned the needle).
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Michael |
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got2boat
5 Posts |
Posted - 04/02/2012 : 22:30:03
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Hi Michael,
That insight about the ECM and the spark really supports your original diagnosis. I'm brining in a different mechanic who does more work with fuel injected engines. His initial thoughts was also that the ECM rarely goes. I'm going to print this out for him too.
I'll let you know what happens.
Thanks again. |
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got2boat
5 Posts |
Posted - 04/20/2012 : 23:18:50
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quote:
Originally posted by B112
3= I personally have not had a connector problem, but I did find two bad wires in my harness. One was the wire going to my distributor (engine stalled) and the other was a sender wire (temperature sender pinned the needle).
Were you able to repair the wire, or did you have to buy another harness?
Since we're not getting spark, I'm thinking it might be the same distributor wire.
To test this, I'd detach J1, I run a continuity test from Pin
3, 10 & 24 to the corresponding wires on the distributor. If I don't get 3 hits it's broken?
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B112
USA
5230 Posts |
Posted - 04/21/2012 : 06:18:26
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>> "If I don't get 3 hits it's broken"? I'd say yes, but I'd also check for shorts between them also.
From what I read, the engine should run (spark) without the computer. A fail safe where the engine just doesn't run well. Thus I'd recheck your distributor, coil and the Ignition control module which is in your distributor.
Take a look at this manual: (see page 4-11 for ohm meter tests)
http://www.pleasurecraft.com/manuals/L510004.pdf
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Michael |
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got2boat
5 Posts |
Posted - 05/17/2012 : 17:40:11
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The diagram you show at the top of the post does not correspond to the "MEFI 3 5.0L EFI and 5.7L EFI Engines" diagram in service manual #24 that was here http://www.maxumownersclub.com/forum/site_files/manuals/mercruiser/24.pdf
It looks like a different harness whether it is Alpha or Bravo.
I can't determine where the wires in question: J1-3, J1-10 and J1-24 connect to the IC module. The distributor is tough to get at, but all I see going into the distributor is White/Gr, White/Red and Black.
According to the diagram, I'm not seeing those wire colors coming out of J1.
Note: I just tried to attach a copy of the page as a jpg file, but it said "this file can not be uploaded". It was about 350K. The diagram in question is page 4E-17 from the manual linked above.
OK, you could browse to this for a full page view:
http://www.freeimagehosting.net/dqsc5
Hopefully this image link works:
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Edited by - got2boat on 05/17/2012 17:56:31 |
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sievert
USA
1 Posts |
Posted - 05/31/2012 : 08:39:28
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| I have a Shamrock with a Mercury engine with exactly the same controller as you have pictures of. The engine works fine up to 1600 rpm, then it coughs. We have changed the distributor and sparkplugs. Is this a controller problem you have heard about? Anybody that can test the controller or should I buy a new one? |
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B112
USA
5230 Posts |
Posted - 05/31/2012 : 10:05:41
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Hum coughs at 1600. I wouldn't think it's the CPU, but a sensor failing to give the CPU the right inputs. Basically the CPU is a set of formulas (remember your algebra days), the inputs are the sensors which are converted to numbers. After the formula is calculated the resulting numbers are used to time how much fuel and when you get it. If your inputs are off, you don't get fuel at the right times. So what you need to figure out is if your spark is failing at 1600 due to the distributor or if your fuel is starving or too much is getting injected. Also, if you have fuel problems, you may need new injectors (which I am told is expensive.)
Bob at MEFI Burn is a great reference. I have all his hardware/software. I wrote my own code also, but he knows the codes for the controllers. Some how he got the codes. He does not have all the codes, though. He also knows how to program these. I intend to experiment based on working with a dyno-shop. Very minor tweaks, and I'll be calling Bob. As long as you buy his equipment he'll support you. |
Michael |
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Mercruiser MEFI-3 ECM Delphi 16237009
