No spark

[handysc]

Working on 5.7 Merc.. Sitting on crate. Can't get spark from coil.. engine cranks but no spark... New coil, new plugs, wires... Is this a bypass issue? Or possibly a ground issue.. Any suggestions would be appreciated.. 5.7 Merc vortex 2001

 

[harringtondav]

"on crate" raises a flag w/me. The factory harness and multi pin connector insure 12V feed to the correct start and run circuits. Also good fuel supply to the (carb?). Not bashing your wiring setup, but a wiring diagram could help. Especially if the engine is TBI or MPI. BTW, how do you plan on keeping this engine cool and glued to the floor once it touches off?

 

[AShipShow]

If it is a carb, I have a video on my youtube channel on how to run a mercruiser on a stand... you might wanna check it out to make sure you're not missing something... if you wire it like I did thru the main plug, you will get power to the ignition system.

 

[achris]

Working on 5.7 Merc.. Sitting on crate. Can't get spark from coil.. engine cranks but no spark... New coil, new plugs, wires... Is this a bypass issue? Or possibly a ground issue.. Any suggestions would be appreciated.. 5.7 Merc vortex 2001

Hello Handysc, and :welcome: to iboats.

In 2001 Merc released 9 models of 5.7... Some had a carb, some EFI and some MPI. Depending on which model you have, the answer to your question will be different. Hint... More of a description, and an engine serial number.

Chris.........

 

[handysc]

Thanks Chris, this is a new long block replacement.. I transferred all the Marine components from my old engine, so not sure serial number will do any good, I do know it has a 2 barrel carb

 

[achris]

Thanks Chris, this is a new long block replacement.. I transferred all the Marine components from my old engine, so not sure serial number will do any good, I do know it has a 2 barrel carb

So what ignition system does it have? TB-IV, TB-V, some aftermarket marine?

If it's a Thunderbolt, then jump into the stickies and have a look at 'How Thunderbolt ignition systems work'. You'll find all you need to diagnose a no spark condition there.

As for serial number, still useful as it identifies all the stuff you transferred.

Chris....

 

[Bondo]

I transferred all the Marine components from my old engine, so not sure serial number will do any good, I do know it has a 2 barrel carb

Ayuh,.... Welcome Aboard,........ You'll need to have the serial number from the ole motor you stole all the accessories from, the number Id's the "Dress" of the new long block motor,.....
Necessary for part identification,.....

Is the little aluminum tag still on the old block,..??
Have ya gotten rid of it yet,..??

I've still got the one from my original motor in my checkbook,..... probably 20 years,....