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Part of engine wirering harness melted?

Started by Marck, December 18, 2012, 06:33:30 AM

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Marck

Hey guys..

I've run into a problem, and need your help..  :brickwall:
The last time I drove the Charger, the engine suddenly stopped, and I coasted on to the shoulder of the highway..
I got it home, and discovered that I had no fuel pressure.. When I turned on the ignition, a little bit of smoke came up from under the windshield, and I found some wires, that were "melted" together.. When I pulled them apart, and turned on the ignition, I had fuel pressure again..
I'm a complete electrical imbecile, and this is as far as my knowledge will take me..  :icon_smile_big:

Now, here's the million dollar question:
Why are they melted? Am I looking a radiation heat from my engine? Some sort of fault in the wires? Perhaps the wires are too thin, and grow so hot as to melt the insulation? I'm more or less just spitballing here, so bare with me..

Thanks for any and all help..  :cheers:


Nacho-RT74

definitelly looks like a short or an overload. That wire drives all the engine power.

It sounds like you are using an eletric fuel pump. Did you sourced the electric fuel pump with relay or not ? If you didn't use a relay, that could be a problem. Overload on the blue line, and engine stopped to get power.

However, by the way it melted, looks more like a short. An overload doesn't melt that fast, is a slow process.

it could be overloaded untill get a cleared area on insulation, then shorted accidentally with chassis somewhere
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

nascarxx29

Look at what wire got the hottest and has no insulation.And back track from there for the cause
Ive seen this damage come from alt field wires shorting  :Twocents:
1969 R4 Daytona XX29L9B410772
1970 EV2 Superbird RM23UOA174597
1970 FY1 Superbird RM23UOA166242
1970 EV2 Superbird RM23VOA179697
1968 426 Road Runner RM21J8A134509
1970 Coronet RT WS23UOA224126
1970 Daytona Clone XP29GOG178701

Marck

Quote from: Nacho-RT74 on December 18, 2012, 10:03:54 AM
definitelly looks like a short or an overload. That wire drives all the engine power.

It sounds like you are using an eletric fuel pump. Did you sourced the electric fuel pump with relay or not ? If you didn't use a relay, that could be a problem. Overload on the blue line, and engine stopped to get power.

However, by the way it melted, looks more like a short. An overload doesn't melt that fast, is a slow process.

it could be overloaded untill get a cleared area on insulation, then shorted accidentally with chassis somewhere

Quote from: nascarxx29 on December 18, 2012, 11:47:25 AM
Look at what wire got the hottest and has no insulation.And back track from there for the cause
Ive seen this damage come from alt field wires shorting  :Twocents:

Thanks guys.

Yes I'm running an electrical fuelpump, and I have no clue if it's done with a relay or not.. I'll have to check to find out, but I suspect it isn't..
I should probably add that I've been running this setup for over a year, and I've probably done 8 - 10 hours or so driving in it.. (Not much - I know)
I don't think it's been in contact with the chassis, but I'm not certain..

Good advice about the wires, I'll go about this the way you mentioned, thank you..

John_Kunkel


The blue wire from the regulator goes to one field terminal on the alternator, a dead short in the alternator will fry that wire and part (or all) of the blue ignition wire. Most common cause of a dead short in that field is a worn brush that allows the brush spring to pop out of its holder.
Pardon me but my karma just ran over your dogma.

Nacho-RT74

totally agreed with the blue field short at alt statement. Is a posibility
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

Marck

Quote from: John_Kunkel on December 18, 2012, 04:45:30 PM

The blue wire from the regulator goes to one field terminal on the alternator, a dead short in the alternator will fry that wire and part (or all) of the blue ignition wire. Most common cause of a dead short in that field is a worn brush that allows the brush spring to pop out of its holder.
Is there any way to see if it's the alt that's at fault...?

johnatkens

Seeing the electronic regulator makes me think that this is an isolated field charging system, grounding the wire from the alt to the reg would full field it and make it charge like crazy but not be a dead short as grounding that wire is what the regulator does to control charging. Grounding the other wire from the ignition ballast resistor would be a dead short however

nascarxx29

Quote from: Marck on December 18, 2012, 11:41:36 PM
Quote from: John_Kunkel on December 18, 2012, 04:45:30 PM

The blue wire from the regulator goes to one field terminal on the alternator, a dead short in the alternator will fry that wire and part (or all) of the blue ignition wire. Most common cause of a dead short in that field is a worn brush that allows the brush spring to pop out of its holder.
Is there any way to see if it's the alt that's at fault...? You can remove alt go to auto parts store for testing.Or inspect brushs and brush holder and fiber insulatators.And wiring coming from the alternator.And check the bulkhead terminal
1969 R4 Daytona XX29L9B410772
1970 EV2 Superbird RM23UOA174597
1970 FY1 Superbird RM23UOA166242
1970 EV2 Superbird RM23VOA179697
1968 426 Road Runner RM21J8A134509
1970 Coronet RT WS23UOA224126
1970 Daytona Clone XP29GOG178701

Nacho-RT74

Quote from: johnatkens on December 19, 2012, 06:34:49 AM
Seeing the electronic regulator makes me think that this is an isolated field charging system, grounding the wire from the alt to the reg would full field it and make it charge like crazy but not be a dead short as grounding that wire is what the regulator does to control charging. Grounding the other wire from the ignition ballast resistor would be a dead short however

the wire what grounding will full field the alt is the green one between reg and alt, but not the blue. Blue is a positive source. Grounding will short out.
Venezuelan RT 74 400 4bbl, 727, 8.75 3.23 open. Now stroked with 440 crank and 3.55 SG. Here is the History and how is actually: http://www.dodgecharger.com/forum/index.php/topic,7603.0/all.html
http://www.dodgecharger.com/forum/index.php/topic,25060.0.html

John_Kunkel

Quote from: Marck on December 18, 2012, 11:41:36 PM
Is there any way to see if it's the alt that's at fault...?

If you have a multi-meter set it on ohms and measure the resistance between the field terminal and the case, should be infinity (zero ohms).

A store tester might not show a fault depending on how it's hooked up.
Pardon me but my karma just ran over your dogma.

johnatkens

Quote from: John_Kunkel on December 19, 2012, 03:43:32 PM
Quote from: Marck on December 18, 2012, 11:41:36 PM
Is there any way to see if it's the alt that's at fault...?

If you have a multi-meter set it on ohms and measure the resistance between the field terminal and the case, should be infinity (zero ohms).

A store tester might not show a fault depending on how it's hooked up.

Did you mean just infinity (no continuity) ?

John_Kunkel

Yes, there should be no continuity between either field terminal and the case....I didn't explain it well earlier.
Pardon me but my karma just ran over your dogma.