Need 3 liter help

[jponfrank]

1996 3.0 225 carb,running at 5000 rpm,all of a sudden the motor shut down,got towed back,no spark on the 3 right side cylinders,left side 3 cylinders top two very weak spark.Any thoughts. Joe

[rchevelle71]

Had that problem with a coil before, they have a common ground, and when one shorts out, they all do, check the coils for short to ground.

[ChrisCarsonMarine]

Merc or Omc ?

[jponfrank]

Mercury

[2stroking]

unplug all 6 cdm's(mercs name for an ign coil), and then plug 1 in at a time till u dont have spark(or weak spark) and that coil is bad.. continue with the rest of them 1 at a time(if u lose spark before you get to them all)-- i had 3 bad ones on a motor i bought.. mechanic couldnt figure it out but he was an omc guy and didnt know a thing bout mercs..`
this should get you going-- 1 last thing i had happen with a 3liter, the boat i dropped my 3liter on was wired for a merc 150.. well they had a metal bracket holding the tach in the dash-- with one bolt having the grey tach sender lead on it and the other bolt at the other side having a ground attached to it.. it should not have run at all according to my merc manual?

but it did run for a couple of monthes till i had another coil go bad(i figured it was dying as i could hear a cyl hitting inconsistently), and after switching to a good coil and idling out of the cove it died when i hit the gas to take off-- pullin my hair after the regular checks i learned that if the grey tach lead gets put to ground the motor (supposedly, but mine did run great for couple monthes like this before having it kill the engine)wont run(directly from the factory 3liter merc manual, but was in a different area then the troubleshooting guide to no spark)..
hope this helps-- should unless another part went-- but it bet its a cdm as they are known for going bad....
--pat

[rchevelle71]

unplug all 6 cdm's(mercs name for an ign coil), and then plug 1 in at a time till u dont have spark(or weak spark) and that coil is bad.. continue with the rest of them 1 at a time(if u lose spark before you get to them all)-- i had 3 bad ones on a motor i bought.. mechanic couldnt figure it out but he was an omc guy and didnt know a thing bout mercs..`
this should get you going-- 1 last thing i had happen with a 3liter, the boat i dropped my 3liter on was wired for a merc 150.. well they had a metal bracket holding the tach in the dash-- with one bolt having the grey tach sender lead on it and the other bolt at the other side having a ground attached to it.. it should not have run at all according to my merc manual?

but it did run for a couple of monthes till i had another coil go bad(i figured it was dying as i could hear a cyl hitting inconsistently), and after switching to a good coil and idling out of the cove it died when i hit the gas to take off-- pullin my hair after the regular checks i learned that if the grey tach lead gets put to ground the motor (supposedly, but mine did run great for couple monthes like this before having it kill the engine)wont run(directly from the factory 3liter merc manual, but was in a different area then the troubleshooting guide to no spark)..
hope this helps-- should unless another part went-- but it bet its a cdm as they are known for going bad....
--pat

Zactly,

that is how I finally trouble shot mine, well kinda. I unplugged them one at a time, 'til it did run, then threw out the one that was bad. Good info on the tach wire, i will have to check into that.

[2stroking]

yeah-- i really was pulling my hair, and of course it happened when we were camping-- drove it back to the camp site on 5cyl but wasnt much different then with the 1 cdm that was going bad anyways and cutting in and out...

but it was strange that someone would directly attach the ground to the tach signal grey wire to begin with! and that it ran fine for monthes, and it was hooked up nice and tight form the day i mounted the 3liter on the boat and it ran fine until one day....
hope this helps anyone reading it, good to knwo to be able to get home if and when it happens! i was back up and running within like 3minutes of the motor dying from the bad cdm!
--pat

[otis311]

lmao look how he signed his name at the bottom of this post...PAT !!! scam artist crackhead !!!
unplug all 6 cdm's(mercs name for an ign coil), and then plug 1 in at a time till u dont have spark(or weak spark) and that coil is bad.. continue with the rest of them 1 at a time(if u lose spark before you get to them all)-- i had 3 bad ones on a motor i bought.. mechanic couldnt figure it out but he was an omc guy and didnt know a thing bout mercs..`
this should get you going-- 1 last thing i had happen with a 3liter, the boat i dropped my 3liter on was wired for a merc 150.. well they had a metal bracket holding the tach in the dash-- with one bolt having the grey tach sender lead on it and the other bolt at the other side having a ground attached to it.. it should not have run at all according to my merc manual?

but it did run for a couple of monthes till i had another coil go bad(i figured it was dying as i could hear a cyl hitting inconsistently), and after switching to a good coil and idling out of the cove it died when i hit the gas to take off-- pullin my hair after the regular checks i learned that if the grey tach lead gets put to ground the motor (supposedly, but mine did run great for couple monthes like this before having it kill the engine)wont run(directly from the factory 3liter merc manual, but was in a different area then the troubleshooting guide to no spark)..
hope this helps-- should unless another part went-- but it bet its a cdm as they are known for going bad....
--pat

[87starflite]

There is a way to bench test the coils with a multimeter. It is deacribed in the service manual. I habe a set of older carb 3.0 coils i will let go relatively cheap if you need them. When mine started failing they all started to fail

[vnemous]

Threads 4
Years old.

[87starflite]

Lol wasnt even looking

[otis311]

Threads 4
Years old.

thread might be 4yrs old but the scammer crackhead 2stroker is still at it screwing people over on this site. Sean Bulka aka 2stroke is a coward scumbag. Dont ever do business with him