Blowing fuse in 5.7 HELP

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imported_Nathan_

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Nov 21, 2003
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Heres the deal It’s a 89 5.7 King Cobra. I bought it in Nov. of last year and have put a bunch of hours on it with no problems.. Sunday we spent all day at the lake with no problems. Well Monday I got a wild hair up my *** and thought it would be nice to go out by my self… well I’m cursing around at 3,500 RPM’s and every once and a while bumping it up.. After about an hour or so The boat just dies …. <br /><br />It turns out it’s the ignition fuse on the dash. I let it cool for about 10 min and push it in and start the boat.. With in 10 sec’s the boat dies again and the fuse popped out. … Ok something’s wrong with the motor… I’m thinking maybe the charging system… So after 10 min or so I start the boat again … that’s when I noticed that the ALT is not charging at all …. Hmm ok … So maybe I’m thinking it’s the ALT gone bad and shorting out or something … SO while the fuse is cooling off I start taking off the ALT belt… I figer this will disable the any type of charge coming from the ALT causing the short. WELL the wire is cooled and I have the belt off… <br /><br />Well here the part that’s getting me ..I turned the key on ON and let it sit for a few sec. And it popped … The motor was not even running…. IS it’s a dead short somewhere on the boat and I have no idea where to start …. I have been having a slight headache with the batteries and the ground… They sometimes get wet, and the ground was getting kind of nasty looking, I added a second ground to the set up Sunday and it worked just fine … I cant help to think that what I did might have something to do with what happened … <br /><br />Heres a like to what my battery set up looks like , <br /><br /><br />Nathan.<br /><br />Austin Tx<br />89 Beretta 23ft. <br />King Cobra 5.7<br />
batteries.bmp
 
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ricky102178

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Re: Blowing fuse in 5.7 HELP

What you did with the ground should have no effect on your problem. Ok here is what I would do 1st make sure the fuse is not defective.2nd Check all the connections make sure there good.3rd I would trace down the wire connected to the ignition fuse both ways. Look for the obvious like a burnt or frayed wire. Make sure the wire is not grounding out. <br /><br /> Hope this helps
 
Boatin Bob

Boatin Bob

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Re: Blowing fuse in 5.7 HELP

I assume you mean you have a breaker and not a fuse if you are pushing it back in. The diagram shows the pos wire out of the switch going to the alt? It should be going to either the starter or solenoid. Do you have a manual with a wiring diagram. When the key is turned to on it supplies power to many things such as the coil (eventually), gauges etc, this will be a process of elimination but should't take too long if the problem is solid. Best to get a meter and start disconnecting the purple wire that goes from the switch. Slim chance possibly that your breaker has gone bad, I think that circuit is around 20 amps, you could jumper around it with an inline fuse just to test.
 
Scaaty

Scaaty

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Re: Blowing fuse in 5.7 HELP

Bad ground will fry a Alternator real quick. You say water getting at the cables. Bet you have also let the A-B battery switch get damp too. And its 15 years old. Although sealed, I could show you one that corroded inside and outside the switch. This paticular boat was bought used. Green cables coming off it and just a mess. Hidden from view to the previous owner, and had a bad alt. Duh! Get a OHM meter and start checking ALL grounds. But I would bypass the Batt switch...go to 2 good cables and try it with the Alt belt off. Still clicks off, do the inline fuse/bypass test that Boatin Bob suggest. BUT I WOULD START WITH THAT A-B Batt switch being the source of your short. And be prepared for serious sticker shock at the price of Alternators...good luck!
 
Scaaty

Scaaty

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Re: Blowing fuse in 5.7 HELP

And also disconnect the alternator wires! If it aint fried by now, it will be with all the fooling around with the wires!
 
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imported_Nathan_

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Re: Blowing fuse in 5.7 HELP

UPDATE .... <br /><br /><br />Had the ALT tested at Advanced Auto Parts and they did not seem to sure on hooking it up to test it.. but they tried it and said it was bad .. With that said I went ahead and wired it back up to the motor but with out the belt and started the boat.. I let it run for about 10-15min and the fuse never popped or did the wires ever get hot ... So the next step is to hook up the ALT-belt and see what happens .. I really have a hard time believing it's the ALT ... I keep the boat dry and it's never sitting to long nor is neglected .. I probably has 200hours on it .. <br /><br />I did test the switch and it tested good.. It is in a spot that will get wet ( not my idea, and is being moved.)) .. I'm hoping that that maybe the switch was way to wet .. I'll keep you posted ..
 
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imported_Nathan_

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Re: Blowing fuse in 5.7 HELP

Well guys I replaced the ALT and check out the AB Switch and put it all back togeather. Ran it in the drive way for about an hour ( on the hose) and had no problems ! <br /><br />I get to the lake and I open her up and she bogs down ( feeling like the 4 barel is not kicking in.) not 10 sec later the freaking fuse pops.<br /><br />I push it back in and start it back up and run about 2000 RMPs back twards the ramp and I made it there fine so open it up again and POP it blew... <br /><br />Well now it was so hot it would not reset and I check to see if maybe the CARB linkage might be in the way and bumping something and it was fine. <br /><br />What do I do ? If the key off after this the fuse still pops .. I'm guessing it's becouse it's still pops.<br /><br />I have left the key on in the boat for hours to see if it will pop and it has not... So this might be water orented ... I checked the bilage and there are no wires that look wet and not much water in there .. <br /><br /><br />Nathan <br />Autin Tx
 
Bondo

Bondo

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Re: Blowing fuse in 5.7 HELP

The Absolute Best way to Find a Dead Short is,<br />Jumper the circuit breaker,+ Look for Smoke.............. :D
 
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imported_Nathan_

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Re: Blowing fuse in 5.7 HELP

smoke .... lol .. Nice ... I'll ust do it at night so I can follow the glowing light coming from the wire. <br /><br /><br />---- After that day when I pulled it from the water the fuse keeped blowing even after 30 min when the motor not running... makes me think of a wire getting wet ... <br /><br />I gues it's time ot pull the garden hose out :-}
 
O

outboardguy

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Jan 16, 2004
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262
Re: Blowing fuse in 5.7 HELP

I've heard that a good way to find a short is by using a compass.Supposedly if you push your breaker in and run along the harness with a compass, when you get to the short the compass should start spinning. Maybe others have heard of this method and can confirm it's truth.Or maybe it's just an old boatsman tale.
 
C

Chum Slick

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Aug 7, 2001
Messages
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Re: Blowing fuse in 5.7 HELP

My friend has similar problems with same engine setup. Lost power to everything. Batteries are good. Battery switches are good. The boat ran fine when he pulled it out of water in fall. He replaced the alternator and now he has no power to any main fuse panels or ignition switch. He does have power to power trim actuator and trim tabs. Could he have hooked up the wiring to alternator incorrectly? I thought it may be a bad ground but I don't know that much about inboard 5.7 engines. Too bad it's not an OMC o/b then I could help him more.
 
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