7.4 mpi no spark
 

Another no spark story.. 1997 gen6 with Delco EST ignition and TB injection..

Ran fine last few days on stand (complete rebuild).. came in this am to install into boat - put my jumper wire on plug that turns on system, 3 mins later i see a huge ball of smoke, coil is FRIED.. Checked ohms from manual, all pass..

New coil, and also another icm - nothing, no spark. On Rinda I did notice 8.5v cranking - maybe the batt cables are not good, ill check that in the am but the same setup has been running fine past few days testing engine on stand. New starter AND battery btw-

stumped. I did read here https://www.offshoreonly.com/forums/...k-again-2.html and some interesting points - i am going to load test the battery cables at the end points to see if they can supply the amps..

Any thoughts? Otherwise stock motor, no mods - freshwater boat.. pretty clean looking..

I did have a 40 and 42 error code but after clearing they havent come back - still no spark!

fwiw - i do have a merc 3.0 EST module i want to pull out of a small ski boat I have and test that..

and yes getting 12.7v at the coil + (thick red wire) when power is on..

what the heck would make a coil fry with power on - nuts.. never seen that-

Its rare but coils can short to ground

https://cimg6.ibsrv.net/gimg/www.off...726a4c9765.jpg

You didn’t ground the coil, did you ?
Grounded tach wire could do it too, i believe.

check these is you have them


https://cimg9.ibsrv.net/gimg/www.off...1c45338251.jpg
https://cimg0.ibsrv.net/gimg/www.off...813237efef.jpg

thanks - verified power to square fuse at at starter, fuel pump does make a noise when I power it on.. Ill recheck fuses again- coil not grounded, its all plug and play.

I ran through the EST ignition tests and all passed perfectly, not a single issue there..

How on earth can a coil get so darn hot - im wondering if the ecu might be faulty. I even unplugged the new alternator to see if that made a difference..

Ill update later - thanks..

I believe the module inside dist shuts off power demand thru coil if engine is not rotating. They did this because old points systems would burn out if key left on and trigger lined up.

What plugs are you using? Are you running a cold or hot plug?

What's that got to do with a no spark condition?

if he’s running copper plugs and not something like platinum or iridium the spark will be super weak ( comparitively speaking) won’t get full combustion and foul the plugs.

just trying to look at every potential issue