electrical short

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If everything goes dead, radio, gauges, headlights, turn signals. dome light? I would check for a loose (open) connection in main power circuit.
 
Any chance the white wire from your MSD box is contacting ground intermittently?
 
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...
Rewired? Did you use crimp terminals and butt connectors? This is not what I would call a short.
There are shorts. The current takes a bypass or shorter route to ground that may no blow the fuse.
Grounds. Generally a wire's insulation is rubbed through and current goes directly to ground. Da fuse, she likely blow.
Opens. There is a break in continuety in the circuit.
Poorly crimped wire terminals on new wiring is an example. Another is the driver door wiring on older vehicles that breaks one or more wires due to flexing when opening and closing the door. For this solder and shrink tube or a butt connector is not the way ti repair this. About 12" of wire should be replaced so that a non insulated butt connecter and shrink tube or solder and shrink tube can be used to make the connections iside the door and under the dash.
On crimp connectors, most are rolled around where you put the wire with a butted up split. If you use a crimper with a u or v shape with a pin on the other side, you need to ensure you put the split in the terminal in the u or v side of the crimper. If you push the pin side into the split, the terminal can open up and give a poor connection. I prefer the uninsulated terminals and connectors with shrink tube to seal the connection. When I worked on heavy trucks, salt water from the roads was a big problem and wiring needed to be sealed. With insulated connectors, I would get the terminal held in the crimper with the split in the u or against one flat. Then inject a bit of silicone sealer into the connector. Carefully push the wire in and crimp. Now reposition the butt connector so the crimp will be parrallel to the first. Push the other end in and crimp. Smooth the sikicone around the connector and wire. Where the pin pushed in, smear a bit of silicone in that to ensure seal. Also smear a bit around the end where the wire just passes through on a terminal to seal all the wire strands and the terminal to the insulation.
For your problem, is it the fuel injection or ignition that is shutting off? These intermittents are a pain to find.
 
Dale Davies said:
Rewired? Did you use crimp terminals and butt connectors? This is not what I would call a short.
There are shorts. The current takes a bypass or shorter route to ground that may no blow the fuse.
Grounds. Generally a wire's insulation is rubbed through and current goes directly to ground. Da fuse, she likely blow.
Opens. There is a break in continuety in the circuit.
Poorly crimped wire terminals on new wiring is an example. Another is the driver door wiring on older vehicles that breaks one or more wires due to flexing when opening and closing the door. For this solder and shrink tube or a butt connector is not the way ti repair this. About 12" of wire should be replaced so that a non insulated butt connecter and shrink tube or solder and shrink tube can be used to make the connections iside the door and under the dash.
On crimp connectors, most are rolled around where you put the wire with a butted up split. If you use a crimper with a u or v shape with a pin on the other side, you need to ensure you put the split in the terminal in the u or v side of the crimper. If you push the pin side into the split, the terminal can open up and give a poor connection. I prefer the uninsulated terminals and connectors with shrink tube to seal the connection. When I worked on heavy trucks, salt water from the roads was a big problem and wiring needed to be sealed. With insulated connectors, I would get the terminal held in the crimper with the split in the u or against one flat. Then inject a bit of silicone sealer into the connector. Carefully push the wire in and crimp. Now reposition the butt connector so the crimp will be parrallel to the first. Push the other end in and crimp. Smooth the sikicone around the connector and wire. Where the pin pushed in, smear a bit of silicone in that to ensure seal. Also smear a bit around the end where the wire just passes through on a terminal to seal all the wire strands and the terminal to the insulation.
For your problem, is it the fuel injection or ignition that is shutting off? These intermittents are a pain to find.
Click to expand...

I dont think its a connector now , took my grandson for a ride yesterday, it didnt do it till it got up to operating temps , mostly so far , 190 .
Got an error code on the handheld again , (about the 6-7 time) , for an 02 sensor code , no way could an 02 sensor kill an engine .
Wondering if there is a short or bad connection on the sensor wire now , when it did it yesterday it seemed to start running rich and funky , but kept running .
Coil , 02 sensor , and many other things have been switch out to test over since this started .... thanks for the suggestions ....
 
I don't know the FAST system, does the 02 sensor have a heater circuit?
Is the code for a rich, lean or heater circuit fault?
Could be a false code due to a momentary rich condition or lean condition?
Do you have an air fuel ratio gauge for both banks?
Could possibly have an injector going full open and cause a rich condition and stall?
Open circuits can be a loose terminal in a connector. pin test time.
 
sounds like a buggered igntion switch to me
presume the FI and everything is switched on and off by the KEY
so has the ignition switch conatct for RUN burned up or the spring that holds the sliding contact onto the switch base contact collapsed. just a short enough disconnect to reboot your FI controller

the effect would be like you turned the key to ACC... i.e some lights but igntion off

you don't need a new switch just hot wire it with screw terminal "chocky Block" and go go for a drive
if the issue is gone... then buy a new switch.

I have a car with a 18 month only switch. nobody makes them or has made them since 72.... i have suffered very similar issues.. freaks me out at 3/4 track, my switch is now made from bits of 2 others and the output of my 3d printer... :)
 
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moparlvr166 said:
If everything goes dead, radio, gauges, headlights, turn signals. dome light? I would check for a loose (open) connection in main power circuit.
Click to expand...
Thanks , but already have , ..ongoing...
Not sure where to start next.
 
famous bob said:
Thanks , but already have , ..ongoing...
Not sure where to start next.
Click to expand...

Fingers crossed , will find out Monday morning : Thursday I found a bare wire going to the elec fan relay , after messing with it it I was too tired and sore to get it down off the blocks to test it . (beat up 76 yr. old) ,rest Friday , funeral Saturday.
Would account for it not doing it till it gets to operating temps need to reseal the h pipe where it slips apart anyway , dont want any clean air getting to the 02 sensor since its so close .
Guessing a live intermitent short will kill the entire fast system , which makes the plugs look pig rich when it happens .............More to come .
 
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