7.4GL no spark problem

[hawkeye9802]

Hi everybody. New guy here so go easy! I am trying to sort out a no spark issue on my 7.4GL Volvo. It has run fine with no issues and after running for a few hours pulling the kids on the tube I shut it off for about a half hour and when I went to restart it cranked normally but didn't fire. I have checked the ignition switch and kill switch and they are not faulty. There is 8.5 volts at the positive terminal on the coil with ignition on. I had an extra coil in the garage and switched that in out of desperation but of course it didn't help. The coil high tension lead fails to spark to ground at all. I can't seem to get the links in the 'adults only section' to open. Can anyone point me to a discussion of trouble shooting the no spark condition for this system?? Serial number on engine is 3868102 as best as I can tell (the numbers on the sticker are faded and hard to read...) Thanks in advance for any thoughts

 

[hawkeye9802]

Additional info: the full model is7.4GL FMDM or PMDM. can't tell if it's an F or a P on the sticker

 

[bruceb58]

You likely have the same ignition system as mine. Is there a large module that sits under the coil? I have been warned that this system was only used for a few years and they weren't the most reliable. i have actually purchased A Delco EST distributor to replace it and will do so sometime in the next few months.

 

[hawkeye9802]

I did not notice a large module under the coil - what does it look like?

 

[bruceb58]

#9 in this picture

 

[hawkeye9802]

nope - i dont have that, unless i am missing it. during my continued searching i have become pretty sure the engine is an "MD" model if i'm reading the numbers correctly which puts it at 1993-4 year which is appropriate for the boat which is a 1994. it seems that the electronic control module is contained within the distributor for these models? (prestolite) I am wondering if it can be tested to see if it is bad without specialized equipment other than a digital multimeter...

 

[bruceb58]

That picture I posted was for an MD model.

 

[hawkeye9802]

crap. i thought i was starting to get this figured out. i was able to get the volvo manual printed off for the MD models and it shows a prestolite distributor which looks like mine with an internal ignition control module. I followed the troubleshooting sequence in the manual and it seems to confirm a short in the ignition control module based on the readings i got. but the coil is mounted in a bracket vertically behind the port side cylinder head, not horizontally over a box like what you showed. ???

i was just about to post and see if anyone knew where to find a replacement sensor/circuit board

 

[bruceb58]

If you get to the point where the replacement parts get too much, this is what I just bought for mine:
http://www.michiganmotorz.com/delco-voyager-marine-electronic-distributor-p-142.html

Not bad when you consider it comes with a new cap/rotor and wires.