Fuel Solenoid Issue?

[Jerome Billett]

Weird problem just started on my 6CTA 8.3s in a Sea Ray 420 AC. Both engines start immediately for past 4 years. Neither engine would start yesterday. Turned over and fired but only ran for a second or so on multiple attempts even with increased throttle. Switched to new racor filters but no change. Primed vigorously with the thumb pump but no change. The fuel solenoids engage with the starters but snap closed (open?) when ignition switch released.
Inexplicably, they both started one right after the other on a subsequent attempt and ran fine for 3.5 hours on a cruise. One other symptom was crazy engine data readings intermittently on the cruise. The dash gauges looked fine and reliable. Also I have the Seaboard EGT dual engine gauge at the helm and was getting no reading on the port engine but what looked to be an inconsistent reading on the starboard gauge.
Today, same thing with no start. Then all of a sudden I get a low oil pressure alarm on my recently installed Maretron alarm system. Both engines then fired right up.
After a 15 minute cruise to the fuel dock and back today, I shut them down and they started again no problem. But tomorrow….who knows?
I am guessing a loose wire connection, common to both engines (maybe a ground?) that controls the fuel flow.
Do you guys have any ideas where to troubleshoot for that? Or have a wiring harness diagram that might show a cross-over point from one engine to the other?
Any insights are appreciated.

Topic

[Rob Schepis]

Well you were on the right track with your original post subject line, your fire shutdown was screwing with your fuel solenoids … nicely done and thanks for posting the resolution, it adds great value when threads are not left open-ended.

[Jerome Billett]

It's the Sea-Fire Module!

Finally solved this one. When the genny started behaving the same way as the mains- start but won’t run, it led us to the Sea-Fire Halon control module. When bypassed, genny started and ran fine. Replaced the module. Everything good now. Thanks for the help guys.

[glenn111]

Soo many weird things going on….batteries OK? or loose grounds.

[Jerome Billett]

Rob,
Thanks very much for these diagrams. I spent a few hours today identifying wires, freshening up a bunch of negative buss bars and engine connections thinking that a common neutral location is the likeliest cause of the problem affecting both engines . One engine connection to the main buss bar was not as tight as I would expect. I will see what happens going forward.
The connectors I could access looked great when unplugged. So many wires disappear into the nether regions of the boat though so this may beat me. Would a Cummins service tech ever know something about an issue like this or have some sort of diagnostic process or is it a needle in a haystack for him too?
I disabled my air heaters a while ago by just removing the main hot wire coming from the starter post to the wire harness. Something still clicks (relay?) in the assembly though when the start engine button is clicked to the run position (not start). Could this have some affect on this problem?

[Rob Schepis]

Below is the link to the wiring diagrams available here. This must start with checking, cleaning, spraying, unplugging/re-plugging etc etc every connection. Yes, you will be doing more than what is needed to eventually find this gremlin but consider it time well spent as to preventative maintenance and understanding of all involved.

Cummins Marine Diesel Engine Wiring Diagrams

[Author]

Replies