Any idea how this wire shorted out?
08-12-2011, 02:59 AM
#1
Any idea how this wire shorted out?
On one of my mercury 250 efi motor for some reason the positive wire that goes on top of the fuel pump got burnt all the way to where it ends, which it goes all the way to the starter selonoid (it goes from the + top of fuel pump to the starter selonoid). Nothing else got burnt just that red positive wire which is very odd. Does anyone know how this could have happened? Where the starter selonoid is, it has a fuse which didn't blow, I would think if a wire get's shorted out it would blow the fuse? Maybe I'm overreacting but could this cause it to fry the ecm? Or do I just need to replace that positive wire? I am really worried that it somehow messed up the ecm on one of the outboards? Please if anyone can help me I would really apprecite it. I have never had something like this happen before. Here are some pictures of it
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08-12-2011, 06:58 AM
#3
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On one of my mercury 250 efi motor for some reason the positive wire that goes on top of the fuel pump got burnt all the way to where it ends, which it goes all the way to the starter selonoid (it goes from the + top of fuel pump to the starter selonoid). Nothing else got burnt just that red positive wire which is very odd. Does anyone know how this could have happened? Where the starter selonoid is, it has a fuse which didn't blow, I would think if a wire get's shorted out it would blow the fuse? Maybe I'm overreacting but could this cause it to fry the ecm? Or do I just need to replace that positive wire? I am really worried that it somehow messed up the ecm on one of the outboards? Please if anyone can help me I would really apprecite it. I have never had something like this happen before. Here are some pictures of it
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08-12-2011, 07:40 AM
#4
If it were drawing more amps, it should have blown the fuse.
BUT......... it appears to be burnt all the way to the solenoid, not sure where the fuse is, I would have to look at mine.
If it were a short, it would only be melted between the short and the pump, not all of the way to the solenoid.
Almost looks as if it overheated, and just melted the whole wire. You got twins right?? If so I would make up a replacement wire, and just run it outside the harness for testing on this motor. If it is fine, then tie it into the harness and assume the old wire just got old, and touched something. If it melts again try switching pumps with the other motor, and see if the issue follows before replacing the pump, they are pricey.
BUT......... it appears to be burnt all the way to the solenoid, not sure where the fuse is, I would have to look at mine.
If it were a short, it would only be melted between the short and the pump, not all of the way to the solenoid.
Almost looks as if it overheated, and just melted the whole wire. You got twins right?? If so I would make up a replacement wire, and just run it outside the harness for testing on this motor. If it is fine, then tie it into the harness and assume the old wire just got old, and touched something. If it melts again try switching pumps with the other motor, and see if the issue follows before replacing the pump, they are pricey.
08-12-2011, 07:51 AM
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If it were drawing more amps, it should have blown the fuse.
BUT......... it appears to be burnt all the way to the solenoid, not sure where the fuse is, I would have to look at mine.
If it were a short, it would only be melted between the short and the pump, not all of the way to the solenoid.
Almost looks as if it overheated, and just melted the whole wire. You got twins right?? If so I would make up a replacement wire, and just run it outside the harness for testing on this motor. If it is fine, then tie it into the harness and assume the old wire just got old, and touched something. If it melts again try switching pumps with the other motor, and see if the issue follows before replacing the pump, they are pricey.
BUT......... it appears to be burnt all the way to the solenoid, not sure where the fuse is, I would have to look at mine.
If it were a short, it would only be melted between the short and the pump, not all of the way to the solenoid.
Almost looks as if it overheated, and just melted the whole wire. You got twins right?? If so I would make up a replacement wire, and just run it outside the harness for testing on this motor. If it is fine, then tie it into the harness and assume the old wire just got old, and touched something. If it melts again try switching pumps with the other motor, and see if the issue follows before replacing the pump, they are pricey.
08-12-2011, 09:03 AM
#6
no... not unless the fuse was actually in that wire. if that wire starts hot at the solonoid and goes straight to the pump, no fuse in the middle then you are talking about blowing the main breaker IF it was a dead short... but a high draw over a long time just heats the wire until it melts.
08-12-2011, 09:21 AM
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I am trying to remember where the fuse is that he is talking about, I am not near my boat right now. I agree that since that is the only burnt wire, it appers that the pump may be drawing too much, but I would make damn sure it is the pump by testing it out with the pump(or other parts) from the other motor, or at least making it burn another piece of wire that is clearly not touching anything else before replacing the pump at almost $600
Last edited by stevesxm; 08-12-2011 at 09:23 AM.
08-12-2011, 09:27 AM
#8
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Since you have twins you can use an ammeter on both and check what the pumps draw. If the pump where the wire burnt is noticeably higher that is your issue. If it is going bad it will draw too many amps and heat the wire, the fuse will not blow until the amps get really high (comparatively) so it just heats the wire and melts the insulation.
08-12-2011, 10:24 AM
#10
So is there a chance it hurt the ecm? I guess I'm just trying to double check, somebody else told me no but I wanted to get on here and ask just to be sure? Also what size gauge wire is that so I know what size to get on the new one?
Last edited by 272bajadriver; 08-12-2011 at 11:07 AM.
