electrical short

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famous bob

famous bob

mopar misfit
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I`ve got one for you guys that are electrical ''smart .''
I developed a short somewhere , the car runs fantastic ,( 505'' , 68 fastback) , has been rewired from day one , even before I built the engine , has been running great for about 2000 miles .
It has developed a short that completely shuts it off when I hit a bump , it does (so far restart immediatly if I am boing fast enough for trans. to drag the engine over. Or I can slip it in neutral and it will restart immediatly.
I had it running ,up on blocks , well warmed up and was wiggling wires ,when I wiggled the power wire to the ign. switch it died , OHBOY , thot I found it , and rewired the power connector! Took it out to fill with 93 oct. and got out on the hi way hit a transition bump going over a bridge
and it died , but was going probly 75ish ,and it restarted , took her home and quit for the day , bummed out bad !!
I have checked and replaced , or tried switching a lot of parts , .even sent all the major fuel inj. pieces back to FAST to check , no problems there .......

WHAT are some opinions on my problem ? thanks in advance .
Car really gets with the program untill I hit that bump ... ....Bob
 
I had a problem similar to that once and discovered my pos. bat. cable cracked. It was at the end before the battery under the insulator and that kept it together intermittently.
 
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Start hitting things with a Big Hammer to simulate the bump in the road. At least you get your frustrations out while looking for the problem.
 
You say, "rewired", describe this. Is it repop/ reworked factory harness, or custom such as Painless, and are you using the factory ignition switch or some "race" toggle box? And do you still have or have you eliminated the bulkhead connector?
 
If this is a factory or factory "style" harness, and you still have the ammeter/ bulkhead connector, I'd start with that. Bulkhead connector, fuse link, ammeter circuit, don't forget the welded splice (in the black ammeter wire a few inches from the ammeter) and the ignition switch and connector

Wiggle wiggle WIGGLE. Strap a test lamp to the ignition power point, and wiggle everything you can get your hands on nearby, while watching the lamp
 
I would make sure you have solid + and - at battery to engine and main power circuit then try a fused 12v wire direct from battery to coil, road test over bumps for a test,
if it does stall you know that circuit is ok. sometimes it's quicker to eliminate good circuits. If you have a tach, try disconnecting it from the coil for a test. Like doing a draw test you eliminate good circuits till you find the bad then dissect it till you find the problem. I disclike intermittent electrical problems they can be very time consuming but easier than body work.
 
famous bob said:
I wiggled the power wire to the ign. switch it died , OHBOY , thot I found it , and rewired the power connector!
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I think you may have found it, but might have made an incorrect assumption that the fault was in the connector. Hold the connector/harness immobile and slowly work your way down the harness trying to recreate the issue. My bet is that you'll find it further down the harness at a bad splice or poor ground.
 
Sounds like people have you on the track to fixing it. My only comment is that it sounds like an "open" not a "short". Short = FIRE or blown fuse. Open is like turning off the power to ignition. Good luck.
 
ACME SS said:
Sounds like people have you on the track to fixing it. My only comment is that it sounds like an "open" not a "short". Short = FIRE or blown fuse. Open is like turning off the power to ignition. Good luck.
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Correct.
 
If you feel you have found the general area of the problem, you may have to unwrap the loom to find any "hidden" problems, broken wire/bad connection/wires shorted together, etc.
 
A56 said:
I had a problem similar to that once and discovered my pos. bat. cable cracked. It was at the end before the battery under the insulator and that kept it together intermittently.
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number 2 battery cable to the front , first thing I checked along with the many grounds I have on it ...........................
 
t
Murray said:
If you feel you have found the general area of the problem, you may have to unwrap the loom to find any "hidden" problems, broken wire/bad connection/wires shorted together, etc.
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thinking of going back there too, have to pull the bucket seat to even worm my way under there , rough on a 76 yr old thats had a broken neck and rotator cuff problems , along with a bad left knee --------------LOL

keep them coming guys , appreciate it !
things I`ve switched out to test , starter and relay, fuel pump and relay , o2 sensor, checked battery cable , and grounds , battery , clamps , key switch , coil , like I said above all components checked out by FAST fuel inj. in Memphis .... probly forgetting something...
 
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famous bob said:
I`ve got one for you guys that are electrical ''smart .''
I developed a short somewhere , the car runs fantastic ,( 505'' , 68 fastback) , has been rewired from day one , even before I built the engine , has been running great for about 2000 miles .
It has developed a short that completely shuts it off when I hit a bump , it does (so far restart immediatly if I am boing fast enough for trans. to drag the engine over. Or I can slip it in neutral and it will restart immediatly.
I had it running ,up on blocks , well warmed up and was wiggling wires ,when I wiggled the power wire to the ign. switch it died , OHBOY , thot I found it , and rewired the power connector! Took it out to fill with 93 oct. and got out on the hi way hit a transition bump going over a bridge
and it died , but was going probly 75ish ,and it restarted , took her home and quit for the day , bummed out bad !!
I have checked and replaced , or tried switching a lot of parts , .even sent all the major fuel inj. pieces back to FAST to check , no problems there .......

WHAT are some opinions on my problem ? thanks in advance .
Car really gets with the program untill I hit that bump ... ....Bob
Click to expand...

Feel around all the wiring connections with your fingertips when that happens. You will definitely feel heat if there is a corroded connection. I have have had those bad connections burn the fingerprints off my fingers when I was looking for the "Short".

Run your fingers down the fuse block terminals and also the firewall harness plug. If it is hot or even warm, there is your problem. Trace it back to the culprit.

☆☆☆☆☆
 
I would check the circuits relating to the coil. Maybe a bad connector. follow it back to the balast resistor. Wire may look good, but give a small pull of the wires and see it one is holding on only by the insulation
 
You still have not answered any questions. More: What is the ignition system, and do you even know if you are losing fuel pressure or ignition? Maybe the ignition system has something wrong with it, instead of actually losing power
 
Pawned said:
I would check the circuits relating to the coil. Maybe a bad connector. follow it back to the balast resistor. Wire may look good, but give a small pull of the wires and see it one is holding on only by the insulation
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no ballast resistor , total rewire ,with fast fuel inj.
 
George Jets said:
Feel around all the wiring connections with your fingertips when that happens. You will definitely feel heat if there is a corroded connection. I have have had those bad connections burn the fingerprints off my fingers when I was looking for the "Short".

Run your fingers down the fuse block terminals and also the firewall harness plug. If it is hot or even warm, there is your problem. Trace it back to the culprit.

☆☆☆☆☆
Click to expand...

thanks , no corrosion on a total rewire...
 
Does the Fast Fuel Inj. system have a data recording capability to scan data? It's a useful tool at dealership level.
 
no ,
moparlvr166 said:
Does the Fast Fuel Inj. system have a data recording capability to scan data? It's a useful tool at dealership level.
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dam thing thru me an 02 sensor code , FAST agreed with me that it wouldnt cause a shut down....still thinking a short under the dash , big problem is , all the wires run over the steering column , definitly no room there in a 68 barracuda .
Guess I`ll have to get another wild hair to get back on it .....
 
When engine cuts out, does the data screen for the fast system cut out also or can you still see data on screen?
 
ACME SS said:
Sounds like people have you on the track to fixing it. My only comment is that it sounds like an "open" not a "short". Short = FIRE or blown fuse. Open is like turning off the power to ignition. Good luck.
Click to expand...
exctly what it does when I hit a bump...
 
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