350 Mag -Wont't start - No buzzer or guages working but has power to keyswitch

[dolemite_1]

Re: 350 Mag -Wont't start - No buzzer or guages working but has power to keyswitch

The saga continues!!!

Ok, So I got all excited hearing about that hidden fuse and looked for it but it doesn't look like I have it. I searched all over and pulled open every wire connection I could find on the engine looking for it. A matter of fact the only wire connection that I came across that had a fuse was the one next to the two connected to the ECM. ( check the Pic, all looked good). Are there more that I am missing?

Next; I swapped the slave solenoid and Circuit breaker between the two engines---- No Good. I have no clue where to go from here. I have attached some photos and a wiring diagram that you posted awhile ago elsewhere don that I believe is for my engine. Trouble is I don't know what half the things are for. Post #7 has diagram ( http://forums.iboats.com/mercruiser...rcruiser-350-mag-mpi-blowing-fuse-558662.html)

 

[Fun Times]

Re: 350 Mag -Wont't start - No buzzer or guages working but has power to keyswitch

It's time we find out if you need to be working on the boat side or the engine side. To do that, first let's unplug and inspect the main harness (10 pin) connector. The 10 pin is in your last pic, http://forums.iboats.com/attachment.php?attachmentid=190810&d=1366857359) between the engine and boat harnesses. Next plug it back in, now with the key on, wiggle and slightly twist the 10 pin connector while watching for the gauges to fire up, etc. If that don't work then your going to need to unplug the harness, substitute a shop harness and key switch assembly and re-run the boat. If the problem disappears, then the problem is in the boat harness, not the MerCruiser engine harness. A suitable test harness can be assembled from the following components:
A. MerCruiser 3 foot instrument harness cable ? part number 84-812475A3 or here's a better price, MerCruiser Style Wiring Pigtail - Mercury Plug, Instrument Side 12" - Hardin Marine
B. MerCruiser ignition switch assembly ? part number 54212A7 or any new 3 prong marine ignition switch will work.
C. Use suitable machine screws and nuts to join the switch?s ring terminals to the harness?s ring terminals, then cover the connections with heat shrink tubing.
D. A standard piezo warning horn can also be added to provide audible warning of cooling system
overheat, low crankcase oil pressure and low drive oil level (or high transmission temperature). No need for warning horn at this point.

Or if you don't want to order the above parts then have a look at this thread and watch the video in post #16,
http://forums.iboats.com/mercruiser...ng-mercruiser-engine-stand-update-368994.html If you're comfortable with making this work, give it a shot because either you or a service shop would be in need of doing this step as a test to help isolate the problem.

Also before you do all that above, See those two black relays next to the ecm in your photo http://forums.iboats.com/attachment.php?attachmentid=190808&d=1366857358 ? Try installing the two relays from your good engine in there and see what you get.

 

[dolemite_1]

Re: 350 Mag -Wont't start - No buzzer or guages working but has power to keyswitch

For purposes of closure and anyone who followed the thread the issue ended up being a faulty killswitch. Thank you to all those who helped.