Electrical ... MSD ... Car shutting down, like I turned off the key ...

Finally we got this thing nailed ... Turns out it was the fuel pump all along :~)

A little long ... sorry

My Mach1 351C 4V with complete MSD ignition (right down to the spark plug leads) including "in the cabin" timing control.

This engine has been shutting off, just like I turned off the key for about a year now (occasionally). I changed out the Blaster coil to no avail. I have not changed out the 6AL box (the $200.00 price tag has kept me from using this as a trouble shooting measure)

I am aware these MSD systems are very "power supply sensitive" and require a specific "power supply voltage" in order to function. It is my understanding that if the voltage drops below what is needed, the system will shut down.

I have noticed ... When this problem occurs it is always when the batttery seems to be getting low.

Could it be that my charging system is not working right and once the battery backup has dwindled, I am at risk of low voltage?

Causing the MSD to shut down?

To complicate this I have the battery in the trunk, which my be contributing to the low voltage issue and possibly even a charging problem.

I need some tips here on: If this thinking is correct .... And what to do to rectify the problem.

I'll be glad to supply more info if needed

_________________

Larry Madsen
Las Vegas Nevada



<font size=-1>[ This Message was edited by: MonsterMach on 5/19/02 1:44am ]</font>

<font size=-1>[ This Message was edited by: Monstermach on 7/21/02 9:14am ]</font>

is your power lead(to msd box)connected directly to the solenoid/large bat lead? Are you running underdrive pulleys? is your msd box grounded to the body assuming your batt is grounded directly to chassis. also do you have a good ground strap from eng to chassis. just remember a good ground is important. just my 2 cents chris

If you think/know/assume that you have charging problems, FIX THAT FIRST, then go onto the problem of messing with the MSD.
It's gotta have GOOD/STRONG (clean), voltage source.
Same, same for ground.
You can never install too many grounds on an electrical system.
My .002

One other thing you can try to see if your box is screwed is to go to MSD ignition.com and perform the test to see if yor box is good.It requires shorting two terminals together I think.
Bob

How big of a cable do you have running to your battery? I would think a person should have at least 6 gauge wire, or even 4 gauge for a battery in the trunk. Make sure you've got a good size wire (at LEAST 8 gauge) connecting the alternator to the battery as well. Voltage drop across a wire is directly proportional to it's lenght. Same goes for the MSD box, if you use too small of wire, you could have 14 volts at the fuse panel, but only 12 volts at the ignition box. Bigger wire is always better in high power applications.

If I were you, I'd get a digital voltmeter and check the voltage on the power lead right at your MSD box. Those things are supposed to operate normally clear down to 10 volts. If you've got a good constant minimum of 12 volts to the box and it still shuts off, I'd have to blame the ignition box.

#2 wire to the battery in the trunk.

I don't own a volt meter ... may need to put that on my next shopping list

I agree, ground it good, check the charding system, &amp; make sure of your power supply. #2 isn't really large enough. I use #0 or #00, no problems with a 6 or a 7.

I would think 2 gauge would be big enough, as long as the starter doesn't have trouble cranking, 2 gauge should be more than enough to feed the rest of the electrical system (uness you're running a baja lighting array or competition stereo, hehe).

I have a nice stereo ... but nothing outrageous ... power amp and bass tube.

Conclusion from folks outside FordMuscle is that I need to go to a bigger Alternator ... move from 61 amp to 100 amp.

Now this is a shot in the dark but it has happened, so stay with me.
Have you ever checked you ignition switch?
with all the power running all the accessories, Fords has been known to corrode the contacts in the switch. Another killer of ignitions is a stack of keys and crap on the ring.
As I said, that is a shot in the dark but it has happened to me , after spending $$$'s on replacement parts and hours of testing.