melted fuel pump

sweebs

Seaman
Joined
Aug 4, 2007
Messages
61
so the big day taking the family out on the river for the first time on a beautiful saturday after wrenching on this new to me boat all summer long came to an end before I even got disconnected from the trailer... Murphy's Law strikes yet again and as soon as the Illinois DNR gets around to issuing my title it's going up for sale, just tired of having a boat that is nothing but a PITA.

symtoms were as follows: boat started right up, idled for 20 seconds then I hear a single click under the dash, engine quits and all the gauges go dead, nothing then happens when key is turned. Wait 30 seconds and it comes back to life, starts up, then 20 seconds later, same thing, over and over. The purple wire at the back of the key switch seemed hot.

Upon inspection - and I can only guess this is related, but I don't how, and definitely don't know why or how this could happen - I see that the fuel pump at the wiring connector is burned up to a crisp and the positive side of the fuel pump terminal is literally broken.

Any ideas on what's going on here? I've literally spent my last dollar on rebuilding the motor and outdrive and can't afford to go buy a new fuel pump right now so my hopes of getting out on the water in my new boat are pretty much sunk, however, if I did somehow get a new pump on there, I certainly don't want to have this happen again.

I can't seem to either load a normal picture as the 2 mb limit prevents it, or the compressed pictures are too tiny to see? Anyway, the 90 degree plastic part of the pump that contains the pos and neg contacts is charred and melted and obviously got way too hot, but the wires feeding the pump do not have any melted insulation and the connector itself is ok.
 

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sweebs

Seaman
Joined
Aug 4, 2007
Messages
61
after removing remaining charred electrical connector remains, exposing the pos and neg leads/prongs coming out of the pump, I connected to 12v and pump still works fine. I soldered leads to the metal prongs of the pump and soldered the other end to the plug in connector (soldering iron not working so used map gas torch), covered all exposed metal and solder joints with liquid electrical tape and am reinstalling on boat to see if the intermittent and repeating problem at the key switch is still apparent. One day asap I'll get replacement pump but for now I'm hoping this will get boat running again.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
The on/off issue you had is an auto reset circuit breaker that opens due to excess current. When it cools it resets for a bit and then cycles again.
 

sweebs

Seaman
Joined
Aug 4, 2007
Messages
61
Thanks Silvertip,, with the circuit breaker tripping then resetting then tripping again and with the melting of the fuel pump at the pos terminal of the pump from apparently pulling too much current through that connection point (yet the pump isn't seized up or otherwise malfunctioning) would you have any idea what is going wrong for this to have happened? Test run for an hour yesterday the boat ran just fine, no issues
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,090
and with the melting of the fuel pump at the pos terminal of the pump from apparently pulling too much current through that connection point

Ayuh,.... Corrosion equals resistance,....

Resistance equals heat,....

That connector failed,....
 

sweebs

Seaman
Joined
Aug 4, 2007
Messages
61
well, after soldering leads to the pump pos and neg prongs and to the connector that previously was attached to the prongs within the black plastic L shaped part of the pump (where the electrical connector from the boat plugs in) so as to be able to plug pump back into connector and connect power and ground, the engine fires up and so far on the muffs, runs just fine,,, ??? Don't know why or how the meltdown occurred/why it was pulling so many amps to cause the leads to melt in half, the plastic connector around the leads to melt/burn/char, the rubber grommet holding the pump to the bracket to partially burn, causing the breaker at the key switch to kill power,, but I sure hope it doesn't happen again, esp out on the river.
 

achris

More fish than mountain goat
Joined
May 19, 2004
Messages
27,468
Ayuh,.... Corrosion equals resistance,....

Resistance equals heat,....

That connector failed,....

And the exact amount of heat can be calculated with P=I2R....

Heat (in watts) is the current (in amps) squared, multiplied by the resistance (in ohms)..

So if you're bad connection has a resistance of 3 ohms, and it's the fuel pump, which draws about 2 amps, then that connection is going to be heated by a 12w heater.... Yep, it's going to burn up pretty quick.

It's massively worse on things like starter motors, as they draw HUNDREDS of amps... Let's say 100amps. A 1/4ohm connection is going to produce 2.5kW, more than the average kettle element... :eek:

Chris......
 

sweebs

Seaman
Joined
Aug 4, 2007
Messages
61
thanks for the help,, I am heading out again today after my bush fix with a few inches of wire, solder and liquid electrical tape, it can't be any worse than it was yesterday and at least today I have a buddy going out that can tow me back if breakdown occurs!
 
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