Blows Main Fuse at 1/4 Throttle???

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Mad Dart

Mad Dart

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Hey guys, anybody had this problem before??

Took my son out for a ride with the new motor. Dang it hauls ***!!
Anyway, all was going good and we were headed home I started to get on it in second gear and at 1/4 throttle it blew the main fuse that is 30amp.

Found the problem instantly put in a new fuse cruzing slow and up my street started to roll into it again and it blew another one. So replaced it and pulled in the garage and for giggles with NO LOAD IN NEUTRAL at 1/4 throttle it blew another one.

It fires right off immediately when I replace the fuse. Never had this problem before!

I have checked and nothing is hanging up on the throttle cable, no bare wires nothing that I can see.

Your thoughts???
 
'64 Cuda said:
Overcharging???
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Gauge says 12-14 Volts on the throttle? I think that is fine unless it spikes so fast and blows the fuse before the gauge can see it??

The alternator is new but I have been Revving the chitt out of it having alot of fun with the car. Possible??

Voltage Regulator?? It is new also?
 
You could prove out the overcharge theory by disconnecting the alternator temporarily and run on battery. Still blows the fuse? Short somewhere and how it relates to the throttle is beyond me. Fixes problem? I'd change the regulator.
 
Gryzynx said:
You could prove out the overcharge theory by disconnecting the alternator temporarily and run on battery. Still blows the fuse? Short somewhere and how it relates to the throttle is beyond me. Fixes problem? I'd change the regulator.
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Good Idea!

I will disconnect it in the next few days when I change out my starter.......Time to get back to work and prepare for NEW YEARS!!
 
you dont have current anywhere near 30a going through regulator, 30a is a lot of current, even if regulator f@@@@d it would only increase volts to battery not amps. that kinda current is a dead short, is cable snagging somwhere ie on body? sleep on it then go double check, hint, big wires = big current,you gotta be looking at cables 4mm upwards, i know on my barracuda there was a thick cable from alternator going thru bulkhead into ammeter in dash, man that cable was toasted! i replaced it, ran another thicker cable in parallel direct to battery solonoid.<keeping ammeter> wiring/electrix just need to be broken down into circiuts and not letting a bunch of wires confuse us, i bet you could single out a hot chick in a room full of uglys? just single out that wire in same way, good luck,let us know
 
cudaboy 67 said:
you dont have current anywhere near 30a going through regulator, 30a is a lot of current, even if regulator f@@@@d it would only increase volts to battery not amps. that kinda current is a dead short, is cable snagging somwhere ie on body? sleep on it then go double check, hint, big wires = big current,you gotta be looking at cables 4mm upwards, i know on my barracuda there was a thick cable from alternator going thru bulkhead into ammeter in dash, man that cable was toasted! i replaced it, ran another thicker cable in parallel direct to battery solonoid.<keeping ammeter> wiring/electrix just need to be broken down into circiuts and not letting a bunch of wires confuse us, i bet you could single out a hot chick in a room full of uglys? just single out that wire in same way, good luck,let us know
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I understand and there is only a few of those type of wires on this car.
Kind of weird that at idle it is fine all day long when that is where the car shakes the most from the lumpy cam. Rev it up where it smooths out and pop goes the fuse. The stock wiring harness has been hacked over the 40 years of its life. Early on when I got the car I cleaned up alot of it when I wired in the MSD Digital 6 Plus ignition. I REALLY will at some point take the time and install a WHOLE new harness for the complete car.

WHERE can you buy a complete harness for a 70 Dodge Dart?? Where do I get it??

I will let you know what I find. Thanks
 
Agreed no where near that current goes directly thru the regulator, but if it sets up the alternator for full charge, well, the current back into the battery could exceed 30A. Fact that the alternator is making current likely indicates that it is working, could have an internal fault that is fully energizing the fields at all times. I'm wondering about this 30A fuse. If I'm right, there is a fusible link in the primary battery supply to the car, but this is a bear to change. Any fuse that is easily replaceable and kills the entire electical system sounds like an add on to me. Can you detail which fuse this is?

Maybe check to make sure the field and stator wires are not reversed at the alternator?
 
Year One for complete car wiring harness
classiccarwiring.com for car wiring diagam
evanswiring,tripod,com for engine compt wiring harness
Several after market companies have wiring harnesses that can be adpacted to mopar use.
 
Gryzynx said:
Agreed no where near that current goes directly thru the regulator, but if it sets up the alternator for full charge, well, the current back into the battery could exceed 30A. Fact that the alternator is making current likely indicates that it is working, could have an internal fault that is fully energizing the fields at all times. I'm wondering about this 30A fuse. If I'm right, there is a fusible link in the primary battery supply to the car, but this is a bear to change. Any fuse that is easily replaceable and kills the entire electical system sounds like an add on to me. Can you detail which fuse this is?

Maybe check to make sure the field and stator wires are not reversed at the alternator?
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When I got the car I believe that someone cut out the Fusable link and added this fuse instead. It is spliced into the back of the bulk head under the dash and is a PITA to get to. It is a far reach for a fat old guy like me.......haaaaaa
 
My suspects.........
1. Your hacked up wiring is not connected correctly or wrong gauge.
2. Bad regulator
3. Mismatch between reg and alt
4. Alt. is higher output than wiring can handle (were those fusible links really only 30 amp??) Seems to me that if the alt is putting out full amperage to charge the battery, the whole current flows through the ammeter and the fusible link to get to the battery. 60-70 amp output....30 amp fuse....sounds like the fuse is doing it's job!
Thanks, Mark
 
cudamark said:
My suspects.........
1. Your hacked up wiring is not connected correctly or wrong gauge.
2. Bad regulator
3. Mismatch between reg and alt
4. Alt. is higher output than wiring can handle (were those fusible links really only 30 amp??) Seems to me that if the alt is putting out full amperage to charge the battery, the whole current flows through the ammeter and the fusible link to get to the battery. 60-70 amp output....30 amp fuse....sounds like the fuse is doing it's job!
Thanks, Mark
Click to expand...

It is weird because the car ran fine for months before I put in the new motor.
The wiring has been the same and it was running fine until yesterday. If it is a direct short it can not be anything that I touched. I actually do pretty good work if you can believe that.......haaaaaa I will check all the other connections in the next few days. I will find the problem and post the outcome in a few days....

Oh yeah I bought the alternator and regulator from NAPA on the same day! I have ran the car and all fine before this issue.

Thanks for your help!
 
I'd say you have a dead short somewhere and when the car moves and shakes it finds its path to ground. 30 amps is a hell of a lot of current to be pulling. Check the top of your fuse box to see if some stray piece of metal (or screw) had not fallen on it. It happened to me and drove me nuts till I pulled it down and found it.
 
Check for exhaust hitting wires underneath the car, unless solid mounted, maybe electric fuel pump wires?

Otherwise pull it into the shop turn off the lights, fire it up, and by hand rev it up and watch the alternator for sparking.
Then check main feeds for tightness on alt gauge posts and strand spots.

and you can check for voltage between the ground post and cable, or is it + post and cable? well' you'll figure it out, I have faith.lol
 
cudajim said:
I'd say you have a dead short somewhere and when the car moves and shakes it finds its path to ground. 30 amps is a hell of a lot of current to be pulling. Check the top of your fuse box to see if some stray piece of metal (or screw) had not fallen on it. It happened to me and drove me nuts till I pulled it down and found it.
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I was thinking the same thing last night!!! I am checking that for sure. 1 thing at a time and I will find it!!
 
1wild&crazyguy said:
Check for exhaust hitting wires underneath the car, unless solid mounted, maybe electric fuel pump wires?

Otherwise pull it into the shop turn off the lights, fire it up, and by hand rev it up and watch the alternator for sparking.
Then check main feeds for tightness on alt gauge posts and strand spots.

and you can check for voltage between the ground post and cable, or is it + post and cable? well' you'll figure it out, I have faith.lol
Click to expand...

Yes I will check EVERYTHING for sure!!

Thanks for all the suggestions!:toothy10:
 
Check around the linkage to the tranny too. There may be something shorting to the linkage when you put it in drive. I would almost bet it is mechanical interference somewhere by the symptoms described. Good luck finding the short. You also said it happens in nuetral. What about in park?
 
Look for a pinched wire. Could have happened when installing the engine.
 
63dartman said:
Check around the linkage to the tranny too. There may be something shorting to the linkage when you put it in drive. I would almost bet it is mechanical interference somewhere by the symptoms described. Good luck finding the short. You also said it happens in nuetral. What about in park?
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It is a 4spd, I will check it out for sure. The only wire there is the Reverse Light harness which is also Brand New.
 
cudamark said:
My suspects.........
1. Your hacked up wiring is not connected correctly or wrong gauge.
2. Bad regulator
3. Mismatch between reg and alt
4. Alt. is higher output than wiring can handle (were those fusible links really only 30 amp??) Seems to me that if the alt is putting out full amperage to charge the battery, the whole current flows through the ammeter and the fusible link to get to the battery. 60-70 amp output....30 amp fuse....sounds like the fuse is doing it's job!
Thanks, Mark
Click to expand...


X2.

Lots to check here, all good suggestions, but I'd look at undoing that 30A fuse mod.
 
Ok, I think I found the problem but it is Weird to say the least.......

Traced all wires under the dash nothing pinched, poked and no bare wire strands on anything. Looked under the hood at all wiring nothing wrong. Then at the bulk head the center harness was very loose so I snapped it back in. Put in a new fuse and started the car. Voltage was around 14 let it warm up and I started revving it not paying much attention to the Volt Gauge. It never popped another fuse in 10 minutes of revving checking etc. Looked at the Voltage gauge and it was only at 11.9. It quit charging. Checked Voltage at Battery 12.05V Checked at the alternator 12.05V and the wrapper on the windings were coming out of the alternator. I think that the Alternator was SPIKING and blew up the Voltage Regulator which in turn was throwing 60 amps at the system when I was revving it up??? I pulled the alternator and it does not sound good at all, like shrapnel and pieces of stuff are in it along with the fins looking like OIL is all over them??

Anyway I will replace both the alternator and voltage regulator tomorrow and give another update........Bought the last ones at NAPA, they are JUNK I only have about 5 hours on both!!!! The Stroker Motor comes on the PIPES QUICK and I guess they dont like it.......haaaaaaaaaaaaaaaaaaaaa
 
cudaboy 67 said:
hopfully you sorted, best of luck man!:read2:
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Ok.............it is FIXED!!!!!!! It was the Alternator doing all of that crud!

Napa swapped out my alternator for FREE.......WOW that never happens to me!! I bought a new voltage regulator but after testing the circut it is FINE...
The car fired right off charging the battery at 13.8V, I revved the dogggg snotttt out of it several times after it warmed up and it is fine!!!

I will clean up the mess I made pulling some tape back on the harnesses but NO BIGGY!!!:cheers:
 
same problem I had been having, they just fall apart inside and usually spark out of the case at high rpm 'if they still work' or are shorting with batt feed after death.
 
1wild&crazyguy said:
same problem I had been having, they just fall apart inside and usually spark out of the case at high rpm 'if they still work' or are shorting with batt feed after death.
Click to expand...

That makes perfect sense, shorting out batt lead. All kind of crap came out of it!!

Thanks for all your input Guys!!
 
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