Engine will not start

Todd320

Todd320

Well-Known Member
Jul 21, 2016
1,508
St. Petersburg, FL
Boat Info
2007 Sea Ray 320DA
Engines
Twin V-drive 5.7L 350 Horizon
At the end of the day, after running the engines 3 separate times today, only 500 feet from home, and tried cranking the port engine, after the normal beep, the engine started to crank, then stopped, then the beep would just come on, then off, then on, then off. Cranked the starboard, no problem. When I put the engine switch into the on position, no beep, nothing. Cranked the generator, turned on the the battery charger (batteries should be fully charged, since I just completed a one hour drive (at 4000 rpm, and 13v the entire time) from Egmont back the marina. Still nothing when I put the port engine in on position. So, opened up the hatch, and the fuse on the starter motor is burnt. See pic. Is this common, or pretty rare? Can I just replace the fuse and boot, or is something probably causing the fuse to fry, and that part(s) needs to be replaced too?
These are 2007 350 MPI

D3E6520B-B44B-4484-AD96-C4CF68919728.jpeg
 
That is a 90 amp fuse, you have a dead short; the alternator would be the place to start on that circuit (orange wire).
 
I did find several older posts regarding a service bulletin where the orange wire from the alternator rubs against something and causes a short. So, will check that first.
 
A short will normally cause a fuse to quickly open. That one looks badly corroded and likely the biggest contributor to it's failure. Did you put a larger alternator on when you replaced it? If the wire is only compromised there, I would start with a new fuse with a clean and tight connection. Replace the terminal as well if it is burnt. You may need to cut it back several inches and add a new piece as well. Looks like the connection was the weak link
 
Thornton69 said:
A short will normally cause a fuse to quickly open. That one looks badly corroded and likely the biggest contributor to it's failure. Did you put a larger alternator on when you replaced it? If the wire is only compromised there, I would start with a new fuse with a clean and tight connection. Replace the terminal as well if it is burnt. You may need to cut it back several inches and add a new piece as well. Looks like the connection was the weak link
Click to expand...
Thanks for the help. If the orange alternator wire is shorted, I should be able to detect this with a multimeter. If the solenoid or starter is shorted, I should be able to detect that as well, correct? If neither tests out shorted, just replace the fuse, boot, etc, and try again? If it blows again, I’m out 30$, I could get an ignition protected circuit 90 amp breaker, found several on amazon, could use that until it pops again to determine where short is...
Mechanic installed mercruiser alternator, so if it was larger, it was something mercruiser approved.
The replacement mercruiser fuse includes the mount, and the boot is another 4$.
 
You'll only be able to use a MM to detect a short in the orange wire if it is CURRENTLY grounded to a part of engine (touchign metal). Just follow the wire, it's easy enough to check.

But 'short' of all that ;) sometimes those starter buttons fuses just pop. From the picture, there appears to be rust/corrosion that has set in under the boot. Rust/corrosion will increase resistance, creating heat.

Check that bronze elbow and hose, as well - it's looking like it's getting short on life (the hose, not the elbow).
 
Lazy Daze said:
You'll only be able to use a MM to detect a short in the orange wire if it is CURRENTLY grounded to a part of engine (touchign metal). Just follow the wire, it's easy enough to check.

But 'short' of all that ;) sometimes those starter buttons fuses just pop. From the picture, there appears to be rust/corrosion that has set in under the boot. Rust/corrosion will increase resistance, creating heat.

Check that bronze elbow and hose, as well - it's looking like it's getting short on life (the hose, not the elbow).
Click to expand...
Thanks. The rust/corrosion could be a result of the water pump failures I had at the end of last year spraying saltwater throughout the engine room, or just age + environment, just a guess. I might buy 2 fuses and replace both (along with hose and clamp). Should I coat in something on a regular basis, like silicone or dielectric grease?
 
Yeah, that could've done it. It could be something else going on, but the seawater spraying on the button fuse is a logical explanation.

Coating connections AFTER they are made is well worth it. Use a LIGHT coating before assembly. Dielectric grease (and other products) inhibits the flow of electricity. If you want to up your game, invest in Tef-Gel :)
 
From looking at the picture, that burn is cause from loose connection. After reparing the burned area,make sure you torque it to specs.
 
You should remove the block and replace it with a Maxi-Fuse to protect ONLY the orange alt feed wire. Wire the Red main system power to the starters main post. That circuit is protected by the 50A circuit breaker. You have the alt protected and should you have a alt failure the motor will still have power to operate
 
Bt Doctur said:
You should remove the block and replace it with a Maxi-Fuse to protect ONLY the orange alt feed wire. Wire the Red main system power to the starters main post. That circuit is protected by the 50A circuit breaker. You have the alt protected and should you have a alt failure the motor will still have power to operate
Click to expand...
If I do this, the fuse should be something <= 40 amp?
I checked out maxi fuse, I had found the one pictured below but have not ordered anything yet.
Thoughts on this fuse, it is 90 amp, ignition protected, and waterproof? I’m tempted to simply use this in the interim until the short is identified and then replace with the standard mercruiser part. If I did bt doctur’s rec, I would get the 40 amp version.
Link: https://www.amazon.com/Tocas-Surface-Mount-Circuit-Breakers-Waterproof/dp/B07D7SH9L9?psc=1
Image of link
886AE096-8BA0-4CDB-AB0D-A0966738AF97.png


Mercruiser fuse:
8A20E1F1-6BFA-404F-AE92-02B91D2E2FA4.jpeg
 
I was certain my tech would be booked and we have a trip with friends planned for this Saturday, so I was planning on fixing it myself. Turns out he had my regular maintenance scheduled for this Tuesday, so he will diagnose the the issue and go from there! Timing is everything. I’ll post the root cause once I know more. After that, he was booked out until June 20th.
 
Tech replaced both fuses and everything is working fine. He believes the fuse was possibly damaged when the alternator died back end of last year. He also stated corrosion might have contributed to heat build up. We will see, 3 day trip starting Saturday.
 
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