Well. That’s not good

[Greyhorse]

insulation possibly pushed in too far and actually under the terminal screw instead of the conductor or partially??

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[MikeyPee]

insulation possibly pushed in too far and actually under the terminal screw instead of the conductor or partially??

No sir. I was very careful about keeping the insulation out of the joint.

 

[Dr. Norts]

It's good practice to re-torque any copper wire connection after it's first tightening / torque. The copper will relax and you'll be able to tighten / re-torque the screw down more. This is extra important if your using extra flex / thin stranded wire as it will relax more then solid / normal stranded.

The fuse most likely didn't blow because the fuse wasn't seeing more current than it's rated value. The high resistance at each side of the screw down connector was most likely due to copper relaxation / heating. Over time this continually will degrade the connection creating more and more heat until something has to give.

Op what material are the terminals in that fuse block? They look aluminum / stainless?? If they are aluminum and you didn't use some kind of oxide prevention grease that also could be part of the problem.

 

[Jay-rod427]

It's good practice to re-torque any copper wire connection after it's first tightening / torque. The copper will relax and you'll be able to tighten / re-torque the screw down more. This is extra important if your using extra flex / thin stranded wire as it will relax more then solid / normal stranded.

The fuse most likely didn't blow because the fuse wasn't seeing more current than it's rated value. The high resistance at each side of the screw down connector was most likely due to copper relaxation / heating. Over time this continually will degrade the connection creating more and more heat until something has to give.

Op what material are the terminals in that fuse block? They look aluminum / stainless?? If they are aluminum and you didn't use some kind of oxide prevention grease that also could be part of the problem.

They are aluminum, but they came with a black coating on them, but op's melted off the coating. I just took mine apart last night and after 8 months it looks brand new.

 

[Dennisn]

Had a buddy of mine had similar thing happen with a blade style fuse holder. Still haven’t found out if the motor Leaned out and blew or not.

 

[TorqueMan]

Conductors can overheat from too many amps or too many volts. The fuse is to protect against over-amperage; over-voltage will not pop a fuse. You might consider checking the voltage at that connection, although I don't know how you would get over-volts as long as the voltage regulator is working properly.

 

[Dr. Norts]

H

Conductors can overheat from too many amps or too many volts. The fuse is to protect against over-amperage; over-voltage will not pop a fuse. You might consider checking the voltage at that connection, although I don't know how you would get over-volts as long as the voltage regulator is working properly.

Higher voltage won't do anything to the conductor. Voltage affects the insulation and voltage ratings on wires pertain to this. Not sure what automotive grade cable is rated at however I'd guess it to be 50-60 volts possibly even higher. Higher for sure if the car is a hybrid / electric.

Too much current / high resistance will overheat the conductor inside melting it or in this case the weakest link - connections.

Too high of a voltage will melt the insulation on the wire as well as nuke your electronics. If the voltage was high enough to melt that insulation you would have lots of fried electronics and not just localized melting as seen in the pics.

Last place I'd look is a voltage spike. Also I doubt it's over current since if your pumps saw that much current in that magnitude of melting it would probably fry your pump as well.

I would throw my money at high resistance at those connections due to things listed in my other post.

Throw a multimeter on Resistance on those two connections. I'm curious what the resitance is between them / across the fuse. It should be less than 1-2 ohm.

 

[TorqueMan]

Higher voltage won't do anything to the conductor.

Overvoltage can most certainly cause excessive heat in a conductor (a wire, terminal, etc.).

Voltage affects the insulation...

Too much voltage will raise the temperature of a conductor which can melt the insulation. That appears to be exactly what we see in the photo; the insulator where the connectors are mounted has melted.

Too high of a voltage will melt the insulation on the wire...

Which results from overheating of the conductor.

If the voltage was high enough to melt that insulation you would have lots of fried electronics and not just localized melting as seen in the pics.

I agree that overvoltage is improbable, but many (if not most) modern automotive electronics include built-in overvoltage protection. If a check of all the possibilities mentioned in this thread hasn't turned up any likely culprits I see nothing wrong with checking the voltage across that circuit, especially when the pumps are first started. I don't know how the circuit is wired, but it's quite easy to get a 100-200 volt spike by interrupting the load on the alternator, and that can certainly overheat conductors and melt insulation.

 

[BlackandBlue]

Overvoltage can most certainly cause excessive heat in a conductor (a wire, terminal, etc.).



Too much voltage will raise the temperature of a conductor which can melt the insulation. That appears to be exactly what we see in the photo; the insulator where the connectors are mounted has melted.



Which results from overheating of the conductor.



I agree that overvoltage is improbable, but many (if not most) modern automotive electronics include built-in overvoltage protection. If a check of all the possibilities mentioned in this thread hasn't turned up any likely culprits I see nothing wrong with checking the voltage across that circuit, especially when the pumps are first started. I don't know how the circuit is wired, but it's quite easy to get a 100-200 volt spike by interrupting the load on the alternator, and that can certainly overheat conductors and melt insulation.

Almost everything you just posted is garbage. Amperage is all that matters. Voltage means nothing until above 250v.

 

[TorqueMan]

Almost everything you just posted is garbage.

Given that everything I said pretty much agrees with what you said, then I guess we're both full of $hit.

 

[BlackandBlue]

Given that everything I said pretty much agrees with what you said, then I guess we're both full of $hit.

I don’t think you understand what you are saying. I could explain but you think you already know and unicorns are not real.

 

[sigintel]

I don’t think you understand what you are saying. I could explain but you think you already know and unicorns are not real.

As a career electrical engineer I must clarify any misunderstandings in this thread:
Unicorns ARE real.

I worked with one recently on a project and she was AMAZING. Taught me that V=IR, I=V/R.
She also shuffled her hooves on the carpet and generated thousands of volts of potential and shocked me with her horn!
Lol.
It made me flinch but no burns or anything.
She also showed me how to weld with a car battery and jumper cables. 1/16 rod and a 100’ roll of romex as a variable resistor for current in the 30-50A range on a 12V battery. Lols.

Edit:
Yea, with current(I) proportional to voltage (V), it seems confusing. Heat/energy generation depends on how much current is available to actually flow at a certain voltage.

You cant weld with two 9 volt batteries plugged in series (18 volt total). But a single 13 volt car battery can blow holes in sheet steel easy.

You can shock yourself with a 40,000 volt lawn mower spark plug and maybe just pee your pants or sneak a fart and a gasp out.
If you grab a live 13,800 volt local pole line while grounded with thousands of amps backing it up..well you are done. Even a 120V line w sweaty hands and you are lucky to be alive.

 

[wproctor411]

Almost everything you just posted is garbage. Amperage is all that matters. Voltage means nothing until above 250v.

You can’t have amperage without voltage. Amperages can increase in a few ways, more load or resistance. A locked rotor on the pump motor, poor pump performance, a bad electrical connection, lower voltage from under performing alternator or voltage drop from undersized or longer wire runs. Voltage drop on 14V systems is brutal which is why we use 24V batteries on most aircraft through a 28V regulator. I would test the system voltage under full load. If the alternator provides 14V at the engine but only 8V at the pump a 40amp load essentially becomes a 60amp load.

 

[wproctor411]

As a career electrical engineer I must clarify any misunderstandings in this thread:
Unicorns ARE real.

I worked with one recently on a project and she was AMAZING. Taught me that V=IR, I=V/R.
She also shuffled her hooves on the carpet and generated thousands of volts of potential and shocked me with her horn!
Lol.
It made me flinch but no burns or anything.
She also showed me how to weld with a car battery and jumper cables. 1/16 rod and a 100’ roll of romex as a variable resistor for current in the 30-50A range on a 12V battery. Lols.

Edit:
Yea, with current(I) proportional to voltage (V), it seems confusing. Heat/energy generation depends on how much current is available to actually flow at a certain voltage.

You cant weld with two 9 volt batteries plugged in series (18 volt total). But a single 13 volt car battery can blow holes in sheet steel easy.

You can shock yourself with a 40,000 volt lawn mower spark plug and maybe just pee your pants or sneak a fart and a gasp out.
If you grab a live 13,800 volt local pole line while grounded with thousands of amps backing it up..well you are done. Even a 120V line w sweaty hands and you are lucky to be alive.

All it takes is .1 to .2 amps to kill a person... Edit - from my school! https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html

 

[sigintel]

All it takes is .1 to .2 amps to kill a person... Edit - from my school! https://www.asc.ohio-state.edu/physics/p616/safety/fatal_current.html

Unicorns can deliver that for sure!

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