Risk of not using a 90 amp starter solanoid fuse

shankos

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Nov 22, 2010
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Hi all.

motor is a 2003 mercruiser 350 mag mpi.

My 90 amp starter solanoid fuse has gone and i was looking at an official replacement part and the cost is around $70-90 in australia for the official fuse which is hefty price tag for a fuse. I was wondering what risk i might be taking if i do not run the boat with this fuse ?

There is a circuit breaker in the ignition line so was thinking it may not cause too much of an issue if i dont replace the fuse. Plenty of motors do not have this fuse. Otherwise might make up a non official 90amp fuse cause it will only cost about $10

Thanks
 

Bt Doctur

Supreme Mariner
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Aug 29, 2004
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19,092
Re: Risk of not using a 90 amp starter solanoid fuse

it`s nothing special, was being called a "lawer fuse" but most older boats never had one.Plus you already have a 50A CB in that line.
 

shankos

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Re: Risk of not using a 90 amp starter solanoid fuse

Ok. I think i will just not bother replacing it. The cost is too expensive for the genuine part.
 

Don S

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Re: Risk of not using a 90 amp starter solanoid fuse

it`s nothing special, was being called a "lawer fuse" .

That's Bond-o's term for it.

Just remember to disconnect the battery before you work around the starter. No doubt you shorted it out with a wrench when working on the engine, just imagine what would have happened if it wasn't there. That 50A breaker wouldn't have protected anything.
 

Bondo

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Re: Risk of not using a 90 amp starter solanoid fuse

Ok. I think i will just not bother replacing it. The cost is too expensive for the genuine part.

Ayuh,.... It seems that the Lawyer Fuse was added 'bout the time 'puters were added into the engine management systems....
To All their motors, 'puter efi, or not..

My motor ain't got a 'puter, 'n I didn't put in the Lawyer Fuse either...
 

shankos

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Nov 22, 2010
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Re: Risk of not using a 90 amp starter solanoid fuse

No doubt you shorted it out with a wrench when working on the engine, just imagine what would have happened if it wasn't there. That 50A breaker wouldn't have protected anything.

I was asking what risk i run without the lawyer fuse being in the circuit and a mistake happens ? What exaclty might i imagine could happen ? I had thought the circuit breaker would be sufficient.
 

Fishermark

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Re: Risk of not using a 90 amp starter solanoid fuse

Without the "lawyer fuse" there is no protection for the main battery cable. If you short that out without disconnecting the battery first... sparks will fly and something will melt or burn. :eek: That's why you always want to disconnect the battery whenever working around the starter.
 

achris

More fish than mountain goat
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Re: Risk of not using a 90 amp starter solanoid fuse

.. That's why you always want to disconnect the battery whenever working around the starter.

Nah, it's more fun 'live'.... :D :D :D
 

Bt Doctur

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Re: Risk of not using a 90 amp starter solanoid fuse

except it has nothinbg to do with a battery cable. thge 90A connection is what supplies power to the 50A breaker, then thru the harness to the dash.
 

Fishermark

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Re: Risk of not using a 90 amp starter solanoid fuse

I actually learned that the hard way - working on my 56 Chevy years ago I was lazy and didn't want to disconnect the battery. I was using a box end wrench on the starter solenoid and touched the other end of the wrench to the metal brake line.... of course then ended up disconnecting the battery AND replacing the metal brake line. At least it wasn't the fuel line. ;)
 

Fishermark

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Re: Risk of not using a 90 amp starter solanoid fuse

except it has nothinbg to do with a battery cable. thge 90A connection is what supplies power to the 50A breaker, then thru the harness to the dash.

Fair enough... that's true. I guess the point is to always disconnect the battery when working around the starter
 

Bondo

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Re: Risk of not using a 90 amp starter solanoid fuse

Fair enough... that's true. I guess the point is to always disconnect the battery when working around the starter

Ayuh,... The Lawyers have done all they can to save the stupid, from themselves....
That's why step-ladders weigh Twice what they should, with All the safety stickers all over 'em....

Common Sense, still rules,... disconnect the battery....
 

achris

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Re: Risk of not using a 90 amp starter solanoid fuse

Ayuh,... The Lawyers have done all they can to save the stupid, from themselves........

I say "let Darwin take control"... :D :D :D
 

Don S

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Re: Risk of not using a 90 amp starter solanoid fuse

Does a 90A fuse blow all by itself? No, Therefore, the fuse did it's job. Obviously, the battery was not disconnected and it prevented further damage.
Had it not been there, we might be reading a thread of the battery blowing up, or the battery terminals melting off, or whatever. Without that fuse, that wire would have been hooded to the starter directly, and very well could have melted the battery cable. Depending on where it was shorted.
That fuse is there for the un-trained backyard DIYer. Not the Mercruiser certified tech.
 

stonyloam

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Re: Risk of not using a 90 amp starter solanoid fuse

Always disconnect the GROUND cable first!!!!! Or you'll be sorrrrry:eek:!!
 

stonyloam

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Re: Risk of not using a 90 amp starter solanoid fuse

Because if you are unbolting the positive (from the battery or starter) with the ground still attached and the wrench touches grounded metal you will get lots of sparks and a very hot piece of steel in your hand.:eek: If cable had been removed from the battery negative, nothing would happen.:)
 

achris

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Re: Risk of not using a 90 amp starter solanoid fuse

I like that answer... :)... But it's a little too 'safe' for me :D :D :D

If you're not living life on the edge, you're wasting space.... ;)
 

Bondo

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Re: Risk of not using a 90 amp starter solanoid fuse

I like that answer... :)... But it's a little too 'safe' for me :D :D :D

If you're not living life on the edge, you're wasting space.... ;)

Ayuh,.... I think, That's why I like you,.... ;)
 

littlebookworm

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Nov 30, 2007
Messages
574
Re: Risk of not using a 90 amp starter solanoid fuse

That's almost as much fun as checking the 120v AC breaker panel with the shore power cable connected and live! A few years ago, while waxing our boat before its splash, I heard a scream and cursing from a nearby, docked boat. The marine mechanic's "assistant" was checking and tightening the screws on the AC circuit breakers without disconnecting the shore power cable. Dumb!!! Hy
 
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