2002 90hp four stroke No signal to bottom coil

[lizard man]

I have a 2002 Mercury 90hp four stroke. It is only firing on two cylinders.There appears to be no signal telling the bottom coil to fire.I know the coils are good because I swapped them around and they both worked.When I unplug the top coil the motor dies and when I unplug the bottom coil nothing changes.Any ideas??
Thank You!

 

[carholme]

Re: 2002 90hp four stroke No signal to bottom coil

What is your engine s/n? If you do not have the service manual, send me a PM, including an email address and I will forward you a copy which has all of the ignition testing.

Gerry

 

[lizard man]

Re: 2002 90hp four stroke No signal to bottom coil

Pm sent. Ser. # is OT449291

 

[Faztbullet]

Re: 2002 90hp four stroke No signal to bottom coil

CPS or ECM...... The crank position sensors tell ecm to fire the coil , failure could be in one or the other..

 

[carholme]

Re: 2002 90hp four stroke No signal to bottom coil

That s/n comes up as:

MERCURY - ( 90 H.P. (2002 ))
Serial No: 0T449291 Model No: 1F90412ZD

Parts and Service Bulletin List for s/n 0T449291:

Search Results - Crowley Marine

Manual on the way shortly.

Gerry

 

[lizard man]

Re: 2002 90hp four stroke No signal to bottom coil

Thanks! Got the manual downloaded.