6.2 MPI Cranks but won't start.

[Merc4ever]

Correct me if I'm wrong but one thing I just checked since I had the coil out was to do this:
https://www.youtube.com/watch?v=rJYJ3KvPhhY


No spark from the coil wire but a big one on the battery, like the coil was shorted out or something when I grounded it.

 

[Merc4ever]

Some say the + and - resistance typicaly reads around 1.2 to 1.5 ohms and that if you get a reading under 1 ohm then your coil is probably damaged mine was 0.8 ohms. Yet again some say it should be under 1.0 and that means mine is OK?

I'm having a hard time finding a replacement for my original Mercruiser coil part 392-8055701 I'm onlly finding 392-805570 A2 not sure if it works or what the difference is.

So I contacted Mercury and they said: "The original part number for the ignition coil on this engine is 392-805570A2. This part in no longer available and has been replaced by part number 8M0079202." So I ordered the Sierra version here from Iboats to see if it helps.

 

[alldodge]

For the most part this is correct but, and there is always a but, there could be other things in play. My thought is to go through the steps laid out in the manual and it will tell you what has failed. A coil is a coil and they all do the same thing but there are differences, this is why the coil originally put on your engine has now been replaced. I hope the coil is the problem, but stepping through the Merc manual is just the way I try to accomplish the task. If the coil works great, if it doesn't we will be here to help some more

 

[Merc4ever]

For the most part this is correct but, and there is always a but, there could be other things in play. My thought is to go through the steps laid out in the manual and it will tell you what has failed. A coil is a coil and they all do the same thing but there are differences, this is why the coil originally put on your engine has now been replaced. I hope the coil is the problem, but stepping through the Merc manual is just the way I try to accomplish the task. If the coil works great, if it doesn't we will be here to help some more

Thanks again, and I agree and appreciate your help. I'm just shooting from the hip and throwing parts at it to get it running before summers over.

 

[Merc4ever]

Come to think of it I'm not really shooting from the hip because I did follow the:Testing Thunderbolt V Ignition System.
My 2001 has the MEFI 3 ECM that uses the old style Mercruiser distributor and coil. I think they changed it over sometime in the 2001 year and scan tool testing is very limited on the MEFI 3. I'm in line with the trouble tree at the point to substitute the coil even though the resistance in ohms tells me it might be good. Next step if still no spark would be > replace ignition module. UGH!

I will be back with results of fixes.

 

[Merc4ever]

While waiting for my coil to come I thought I would jump to the next step on the trouble tree and test the ignition sensor. So for those with similar problems I unplugged the white/green and white/red wires that come out of the distributor and checked the resistance between them. It's suppose to be not less than 100 ohms and I was in the Mega ohms so I guess that means it is OK? While unplugged, the pink wire had 12 volts as it should, and the purple white wire had 5 volts comming from the ECM as it should.

So now I'm back to the coi,l or the white wire coming from the ECM because I have the 12 volts needed on the red wire. There's no usable test for the white wire that passes through the J1-2 pin and into the ECM according to the diagnostic supplement service manual 24. So if the new coil don't fix the problem it's looking like it comes from inside the ECM and that is a nightmare for me.

 

[alldodge]

What is your engine serial number?

 

[Merc4ever]

0M030333

 

[alldodge]

0M030333

This does not add up, this serial says you have a 1998 5.0, your thread says you have a 6.2 which should put you in the serial range of 0M300000 and up. If you have a 5.0 and the serial number is correct then manual 24 is correct I need to rethink. If it is a 6.2 then your in the wrong manual

 

[Merc4ever]

Here's the serial number range for my 2001 6.2

0L680003 THRU 0M299999 At least that's what a parts look up link shows and the parts are the same numbers as mine.

 

[Merc4ever]

This does not add up, this serial says you have a 1998 5.0, your thread says you have a 6.2 which should put you in the serial range of 0M300000 and up. If you have a 5.0 and the serial number is correct then manual 24 is correct I need to rethink. If it is a 6.2 then your in the wrong manual

Now I see what you found, I used the supplement to 24 manual it's for 377 CID (6.2) They must have just added the 6.2 to the line then that's probably why I got the early MEFI 3.

Here is the one that I used: http://www.blainehanson.com/Manuals/...0377%20CID.pdf Also the distributer is the same as the one in the main manual 24 for the Thunderbolt ignition I believe, it has only one coil.

 

[alldodge]

While waiting for my coil to come I thought I would jump to the next step on the trouble tree and test the ignition sensor. So for those with similar problems I unplugged the white/green and white/red wires that come out of the distributor and checked the resistance between them. It's suppose to be not less than 100 ohms and I was in the Mega ohms so I guess that means it is OK? While unplugged, the pink wire had 12 volts as it should, and the purple white wire had 5 volts comming from the ECM as it should.

So now I'm back to the coi,l or the white wire coming from the ECM because I have the 12 volts needed on the red wire. There's no usable test for the white wire that passes through the J1-2 pin and into the ECM according to the diagnostic supplement service manual 24. So if the new coil don't fix the problem it's looking like it comes from inside the ECM and that is a nightmare for me.

According to the troubleshooting path for a TB-V, if you replace the coil and can strike the wht/grn (in your case white wire) wire to ground and get no spark, the ignition module is replaced. Your systems indicates the ignition module is part of the ECM.

Main Power Relay test. With ignition ON can you get voltage on pin 86 of the MPR?
If so, Check continuity between MPR terminal 85 and ECM connector A-22.
Do you have at least 35psi of fuel pressure at the fuel rail, and does not drop immediately to zero afterwards?
If pressure does not stay up ECM will not cause spark due to ECM will not pulse injectors

 

[Merc4ever]

No spark when striked, I even pulse it 3 times a second and still no sparks anywhere not on the primary wire or the secondary with a spark tester hooked up.
Fuel pressure I assume is OK because the pump cycles and I watch the ECM display tool saying "on" then it apparently gets satisfied and says "off" and my rail is pressurized with fuel. I'm not sure if it's 35 psi because I have no accurate gauge but I can get one if you think it's important.


Yes there's power on MPR pin 86 but not sure about that A-22 or where it is, maybe you mean J2-32?


With only 289 hours on this well maintained, never dock stored 2001 that's less than 23 hours per year and probably only about 8 this year. I wouldn't expect many parts to be wore out yet?

 

[Merc4ever]

Your systems indicates the ignition module is part of the ECM.

I really hate the sounds of those words even though they are so true. My MEFI 3 ECM is no longer available so Merc has a MEFI 4 kit with harness 892797A01 and it's almost 4 thousand bucks! One good thing it has an external coil driver but I still don't have that much extra cash right now.

 

[alldodge]

I really hate the sounds of those words even though they are so true. My MEFI 3 ECM is no longer available so Merc has a MEFI 4 kit with harness 892797A01 and it's almost 4 thousand bucks! One good thing it has an external coil driver but I still don't have that much extra cash right now.

Have only done some short searches and I see the 4K kits but also see the 800 dollar kits. There is a thread about this subject on OSO and the guy that owns BAM and other sites mentioned he has some back then. I would suggest contacting him and see what he can offer. Did find in the thread that repining your current harness might be the way to go.
http://www.offshoreonly.com/forums/drives-lower-units/276268-need-mefi-3-ecu.html

 

[Merc4ever]

Have only done some short searches and I see the 4K kits but also see the 800 dollar kits. There is a thread about this subject on OSO and the guy that owns BAM and other sites mentioned he has some back then. I would suggest contacting him and see what he can offer. Did find in the thread that repining your current harness might be the way to go.
http://www.offshoreonly.com/forums/drives-lower-units/276268-need-mefi-3-ecu.html

Thanks, and you were right the new coil came today...it's not the coil. :blue:

 

[Merc4ever]

There must be some way to check the white - wire coming from the ECM to test the coil driver to make sure it's bad before I take the giant step to replace this ECM? Or maybe not?

 

[alldodge]

My understanding is you tried to get the coil to spark and it did not. Well if you can put 12V on the red of the new coil and touch the white to ground you should get a spark. If you still don't get spark, something in the setup is wrong

 

[Merc4ever]

I sent a E Mail to Mercury, maybe they will help me on this they did with the coil order numbers.

 

[Merc4ever]

http://www.marinemechanic.com/merc/d...i3-nostart.PDF

Hmmm this is interesting maybe there's still some hope in not replacing the ECM.

Not my engine serial numbers but the same ingniton sensor, I wonder...