electrical problem ?? need help

[deputydog]

I have a 73 401 amx that ran great, parked it, went to start it the next day. no power anywhere. Battery is fully charged and have power to the starter relay but no power any where else. fuse box has nothing, headlights nothing. if I jump the starter relay it will turn over but not start. power seems to stop there. where should I start the trouble shooting?

Thanks

[Big Bad AMX]

I had that problem years ago in my '69. Poof. Everything was dead. Bypass the tach and/or Amp gauge and I bet you'll find one or the other is causing the problem.

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[304_dude]

Hi, yes there is a lot of issues with the Amp meter and wiring. Problem is when the driver starts the car. I find a lot of burnt up amp meters from over cranking the engine. The hi-comp 401 and 390 can kill wiring and meters very easy through time. Fortunatly it is a simple fix, but is not stock.

For those who don't have this issue yet and have not beefed up their wiring to the amp meter and replaced it with a mod (see bottom two paragraphs), you can still save yourself some time and troubles.

The best way I have found to start hi-compression engines that are slow at starting up, is to shoot a little starting fluid in the air cleaner and do short starts. When I mean short starts you are to crank the engine for no more than 5 seconds and stop for 1 minute. Why? The amp meter gets hot very quick and so does the starter. The higher heat will consume more current, and cause amp meter or wiring burnout.

My mod for 71 - 74 Javelin AMX with go pac:

I killed a 71 - 74 Javelin temp or fuel gauge and made it into a custom voltmeter using the burnt out amp meter. In doing so I also had to print out a custom volt scale as a lable to go over the amp meter. I carfully cut the length of the needle on modified gauge. I connected ground to one of the leads to the gauge and left the lead from the batt side starter solenoid. You will need to add a 1/2 watt resistor the meters mesured resistance at the two teminals - (.13 x meters resitance). This will place 13.8 volts about 5/8 of the meters range. The resitor can be mounted anywhere on the batt lead to the meter. Depending on the which meter you use, the batt side terminal can be tested by applying voltage (by quickly touching) to the meter with one terminal grounded. if the meter moves the wrong direction just reverse the connections to the terminals. I dont know how to save picture here... So I cannot show you mine.

Another is to beef up the Amp meter wiring... this is not stock at all since the diameter of the wire is larger. As for the amp meter some careful changes are to be made. Mainly to heat sink the body (not the strip of metal that pulls the needle) secondly to add old style power window circuit breakers 5 in parallel (they can be placed anywhere as long as they are in line with the Batt side of the Amp meter. The curcuit breakers should be rated at 15 amps.
In parallel the total current will be the sum their current rating. Since the Amp meter is to mesure 80 amps max the maximum current you want should be no more than 75 amps.

[donsjave]

Do not forget to look at the fusible links on the car. There is something like 6 of them located thoughout the car. There is one for the starter from the ignition switch. Just a thought

[AMC maniac]

Do not forget to look at the fusible links on the car. There is something like 6 of them located thoughout the car. There is one for the starter from the ignition switch. Just a thought

i have a 73 chevy caprice estate wagon that did the exact same thing i was driving and all of a sudden i had nothing, no lights, power windows, starter, etc, my hazards didnt even work! the fuse link that was bad was the one from the horn relay to the bulkhead, its a GM but mabey AMC was the same! good luck