New Mercruiser 5.7 Vortec - EST - No spark

Hello, I recently purchased a boat that needed a new engine. This was the only way I could find a boat that looked nice enough to take the family out in, so I knew I would have plenty of elbow grease to go in to it. I purchased a new 5.7 Vortec 4 BBL with a Delco EST ignition. This is the first time I've tried to start the engine. The problem I am having is that I am not getting spark.

I checked the following:
--I have 12v to the purple wire on the coil
--I have 12v on both of the wires (pink and brown) that come straight from the ignition module (terminals + and C) to the coil
--I have 12v into the black wire that plugs into the ignition module (one without the shunt loop - terminal B)
--I disconnected the tachometer to make sure it wasn't grounded causing a loss of spark
-------No spark in this configuration-------

--I have spark when I plug in the shunt plug (the one with the little white jumper wire for setting the timing -terminals R+E), the black wire (terminal B) has 12v.
--I also have spark if I disconnect the terminal GBRE plug.

I hope this makes sense to someone, and you can provide me some assistance. Thanks!

Re: New Mercruiser 5.7 Vortec - EST - No spark

What year was the old Mercruiser engine. What distributor and ignition system did it have before. What outdrive?
None of the 5.7 Mercruiser carbed engines ever used the EST distributor. I would bet you have a wiring conflict around the shift interrupt system, but not sure yet.
IF, you have an Alpha outdrive, leave every thing wired as you have it, but try disconnecting on lead to the shift interrupt switch and see if the engine will run.

Re: New Mercruiser 5.7 Vortec - EST - No spark

Old engine was a 1998 Merc. 5.7 non-vortec 2 BBL. It had an ECM mounted separately to the back of the distributor (thunderbolt V).

Outdrive= alpha gen 2?

I purchased a new merc engine which included the new 4 bbl carb (edelbrock) and the EST distributor.

I currently have the shift interrupt system (both wires) disconnected.

I just don't understand why I get spark with the shunt timing wire inserted. Thanks Don for the assistance!

Re: New Mercruiser 5.7 Vortec - EST - No spark

Here is how the wiring should be hooked up. While it's for a 3.0L, the wiring for the distributor is the same.

Re: New Mercruiser 5.7 Vortec - EST - No spark

Don, thanks so much for the help.

yes, that is the way I have it wired, with one exception, the white/green wire comes from the old ECM which was eliminated. So essentially there is no longer a shift bypass (although I will add one back in). Instead of the white/green which provided +12v from the old ECM, I am sending +12v straight there from the alternator to the new ICM. I have not tried to start the engine yet as I am trying to confirm that I have spark before I put the risers, etc back on the boat. The only way I see spark is with the two white jumpers connected together.

Interestingly enough, I was looking through some of my wiring diagrams, and I see that on a throttle body injection model, the IC module is wired differently. Thoughts?

Re: New Mercruiser 5.7 Vortec - EST - No spark

A carbed engine does not have an ECM, they have a ICM (Ign. Control Module) don't confuse the two, they are completely different animals. Only EFI engines have ECM's and it controls all the engine functions by comparing sensors on the engine.
A carbed engine has none of that.

Re: New Mercruiser 5.7 Vortec - EST - No spark

Thank you. so here is what I see then,

yes, that is the way I have it wired, with one exception, the white/green wire comes from the old ICM which was eliminated. So essentially there is no longer a shift bypass (although I will add one back in). Instead of the white/green which provided +12v from the old ICM, I am sending +12v straight there from the alternator to the new ICM. I have not tried to start the engine yet as I am trying to confirm that I have spark before I put the risers, etc back on the boat. The only way I see spark is with the two white jumpers connected together.

Interestingly enough, I was looking through some of my wiring diagrams, and I see that on a throttle body injection model, the IC module is wired differently.

Am I sending the +12v to the wrong place?