ignition sensor assembly and coil questions

Joined
Jun 3, 2009
Messages
15
Anyone have a history with one of these failing or going bad?

I am having a problem with my boat running strong and then NOT restarting. Just cranks. Then the next day starts great.

Could this be the culprit? What about the coil, can it create this issue?

5.7 Mercruiser with Digital Ignition
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: ignition sensor assembly and coil questions

You will have to be ready to test everything when this happens. Check for spark, if none then test the coil, you have to be ready with some jumper wires for that. If the coil can be made to produce a bright spark manually then it could be the pickup inside the distributor. It will be hard to diagnose the next day because there are too many components that can add to the mix....battery connections, battery itself, tachometer component or wiring, igniton module, ignition pick up component or wiring, etc.


I had a hot-restart problem like that with a car. I had restored it with new wiring harness but had upgraded the ignition and used a harness from a newer car to supplement the part that was not available with the Repro/OEM harness. I did not take all the wrapping off of the used harness because it looked untouched, but should have, someone had spliced the wires that went from the distributor pickup to the ignition box and done a very poor job, like 2 or 3 strands hanging on for dear life on 2 wires. Once I found that and fixed it the hot start problem went away. This is just an example of what can affect older installations.
 
Joined
Jun 3, 2009
Messages
15
Re: ignition sensor assembly and coil questions

Mercury 5.7 with EFI om024970

I will order the manual. Just grasping at straws!

Any history with ignition sensory assembly?

I did have carb on a 5.0 that had choke issues. You could just crank it wide open and it would eventually start. Not this one. Just cranks
 

scruffytoad

Recruit
Joined
Jun 19, 2009
Messages
1
Re: ignition sensor assembly and coil questions

I have a 2000, Mercruiser 5.0L EFI that died on me as I was idling out of the marina and then wouldn't restart (not even the next day). It ended up being the ignition sensor. This was found by first checking for a spark.

If it restarts the next day OK - you may want to think about vapor locking & possibly installing a check valve to solve it. There are lots of threads on that topic as well.

Best of luck!
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,986
Re: ignition sensor assembly and coil questions

I will order the manual.

Ayuh,.... The factory manuals are Free, up in the Adults Only section of this forum....
 
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