MSD 6A / MSD 6AL Ignition issues. HELP. [Archive] - FSB Forums

: MSD 6A / MSD 6AL Ignition issues. HELP.


malibufreak78
03-06-2007, 11:39 AM
85 Bronco
351W
Mallory Unilite Distributor
New cap
New rotor
MSD 6AL Ignition
Blaster coil
Wires - Accel 8mm Super Stock Radio Supression wires
Plugs - .050 Type - Autolite #25's
Headers - (No cats)
Mechanical fuel pump
No factory electronic engine controls of any sort.

The distributor and the MSD 6A were already in the truck when I bought it. I replaced the 6A with a 6AL.

I just removed my MSD 6A ignition box due to some obvious failure. At least I think! (I know that sounds dumb but read on)

MSD 6A:

1. It will start the truck and maybe run for a minute or two and then shut off. Some times it will run the truck for 30+ minutes before shutting off.

2. I will try to restart it but it will not start. After anywhere from 1-5 attempts at restarting, it will fire right up. Sometimes after the first retry and sometimes after the fifth. :banghead

3. Ignition box does not make any sound at all while the truck is running.


MSD 6AL:

1. It will start the truck and maybe run for a minute or two and then shut off. Some times it will run the truck for 30+ minutes before shutting off. :scratchhe

2. I will try to restart it but it will not start. After anywhere from 1-5 attempts at restarting, it will fire right up. Sometimes after the first retry and sometimes after the fifth.

3. Ignition box makes a buzzing sound when the truck is running. (Sounds like you can actually "hear" the Multiple sparks discharging!)


This dang thing is really pissing me off here.

I have the MSD 6AL box wired directly through a 12V source direct from the battery and the reading is at 14.2V while the truck is running. I wired it directly from the battery to do away with any of the power supply problems that are normally associated with the ignition switch and/or relay being bad.

I have the green, red and brown wires coming from the distributor that plug directly into the MSD 6AL.

The small red wire coming from the MSD 6AL that goes to the distributor reads 12.8V when the MSD is turned on. The white wire also reads 12.8V. (Due to the way the instructions call for it to be wired, the 12.8V at both wires is correct.)

When the truck starts, the white wire voltage drops to 3.5V to 3.9V. :shrug

Now the fun part: when the truck shuts itself off, I check the voltage at the white wire and it is back at 12.8V. I try to restart the truck and it will not start until the voltage at the white wire drops back down to the 3-4V range. WTF.

After I turn the truck over 2-3 seperate times, the darn thing may or may not start.

I know one thing for sure..........The Bronc will not start while there is 12V+ at the white wire.

WTF? I am about ready to dump some gas inside and throw a flare in there and watch it burn.

I give up !!!! :whiteflag

bigrob
03-06-2007, 11:53 AM
which do you have? the 6a or th 6al? or both?
either way.....rip it out and throw it in the nearest trash receptacle....or sell it to someone who actually thinks it'll make a difference.:rofl:
go with duraspark, or try another brand ignition box.

malibufreak78
03-06-2007, 11:58 AM
I had the 6A and then replaced it with the new 6AL.

I have NEVER had a problem with an MSD box and I actually prefer them over a stock type ignition. (Not trying to sound difficult here)

I know, I know, Duraspark is the cats meow. But....that is not what I have to work with.

The Duraspark would be okay if it wasn't going to cost me as much to get as what I already have.

I would have to get the module, the distributor and then pray that there was not something wrong with the factory wiring.

Damn. I think I am going to have a bonfire soon.

I am going to be replacing the 351W with a 460 sometime in the near future, but I want to make sure everything works with the 351W (MSD and all) before I go and put it in my '72 Maverick Grabber.

SigEpBlue
03-06-2007, 01:04 PM
Actually, the operation you describe for the MSD boxes is correct. To determine if the box is working correctly:

Disconnect the WHITE wire
Disconnect the coil wire from the distributor cap
Put a spare spark plug or ignition tester into that coil wire, rest on a metal ground surface
Turn on the ignition switch
Tap the white wire to ground rapidly; each time you disconnect from ground, you should see a spark.


If it doesn't operate as described, then it's a problem with the ignition box or coil. If it does as outlined, then you know the problem lies upstream, i.e. the distributor or wiring. I would honestly suggest checking and searching MSD's forums. They've actually got techs roaming around and they're pretty good at nailing problems of all kinds.

malibufreak78
03-06-2007, 01:51 PM
[QUOTE=SigEpBlue;1183406]Actually, the operation you describe for the MSD boxes is correct. To determine if the box is working correctly:

Disconnect the WHITE wire
Disconnect the coil wire from the distributor cap
Put a spare spark plug or ignition tester into that coil wire, rest on a metal ground surface
Turn on the ignition switch
Tap the white wire to ground rapidly; each time you disconnect from ground, you should see a spark.
.

Did all of that. BOTH the 6A and the 6AL are working properly when I do the above steps. See why I wanna torch it.

Thanks for all the help thus far. Anyone else that is running the 6BTM or any other type of MSD have any other symptoms that sound like mine?

imlikeojnow
03-06-2007, 02:35 PM
What do you have your 12 volt ign on source hooked up to? I was reading that you can not have that hooked directly to the battery or it cause failure in the box. the only reason i was reading on it is because i am getting one and want to know what they are all about. maybe the wrong box though i dont remember off the top of my head.

malibufreak78
03-06-2007, 02:52 PM
toggle switch is connected directly to the battery.

The MSD instructions show that it needs the be connected to the power source. (I would think that 12V is definitely an acceptable source)

Link to MSD installation instructions: http://www.jegs.com/pdfs/121-6420.pdf

My set up is on page 23 of the manual.

These are the Specs of the 6AL ignition:

MSD 6420 6AL Ignition Control
Rev Limiter
4 Cylinder, 6 Cylinder (Even-Fire Only), 8 Cylinder Engines
MSD 6420 Instruction Sheet
121-6420

MSD 6420 6AL Ignition Control delivers everything the 6A does with the addition of a built-in Soft Touch Rev Control. This feature allows you to set an RPM limit to protect the engine from over-rev damage caused by driveline failure or missed shifts. Other MSD RPM Controls can be connected to the 6AL such as a Three Step Module Selector or RPM Activated Switch . The 6AL also comes supplied with rubber shock mounts and 3000, 6000, 7000, 8000, rpm modules.All necessary parts and wiring instructions are included.50-state legal via EO#D-40-26.


--------------------------------------------------------------------------------

OPERATING SPECIFICATIONS
Operating Voltage: + 10-18 VDC, Negative Ground
Current Requirements: 5 Amps-5,000 RPM, 10 Amps-10,000 RPM
RPM Range: 15,000 RPM with 14.4 Volts
Spark Series Duration: 20° Crankshaft Rotation
Energy Output Max: 105-115 Millijoules Per Spark
Weight And Size: 3lbs., 8'' L x 4'' W x 2-1/4'' H
Voltage Output Max:Primary - 460-480 Volts, Secondary - 45,000 Volts (Blaster Coil)

SigEpBlue
03-06-2007, 03:30 PM
I looked through all of the .pdf documentation for both MSD 6-series boxes and Mallory Unilite (heh, didn't know Mr. Gaysket owned them too :rolleyes: ) distributors, and pretty much it looks like a very basic setup and wiring. Good freaking Lord that Mr. Gaysket website is fawking horrid!!! :uke:

Anyhow, here's what the schematic from MSD looks like:
http://www2.gvsu.edu/~burnards/My%20Pictures/MalloryUniliteToMSDSchematic.jpg

Assuming this is a points distributor, are you sure that they're adjusted correctly, and that your condenser isn't malfunctioning? Bear with me here, I want to make sure that the wiring isn't the crux of any problems too. :D The reason that white wire's voltage fluctuates is because that's how the ignition box determines when to fire. Your ignition coil -- and everyone else's for that matter -- fires when the ground connection is removed from the "-" side. So when the distributor's GREEN wire (which is connected to the WHITE MSD box wire) goes to +12V, you're actually seeing a lack of ground, which is when the coil would be firing.

If the MSD boxes have tested out to be good, then you're left with the two possibilities of a bad distributor or wiring.

malibufreak78
03-06-2007, 06:24 PM
SigEpBlue - That is what I have. That is the way I have it connected. I just substituted the ignition switch with a toggle switch that would feed the 12V to the box. 12V is 12V no matter where it comes from.

Sumbitch. This ignition problem is kicking my..............@ss.

I have re-gapped my plugs to .050 from .045. They are the Autolite #25. I am going to go get me some new ones and put them in and see if that helps.

Timing is set at 10* BTDC.

The wires are Accel 8mm Super Stock Radio Supression wires.

jcbronco
03-06-2007, 08:54 PM
If it was doing it after the engine warmed up, I would suspect its too close to a source of heat. One of the guys at the "pump gas drags" in Memphis a few years ago had mounted his too close to the headers and during the cruise it cut out on him. Once it cooled, he went on but got a DNF for breaking down on the cruise. Since yours is intermittent, I would suspect a loose connection. And if it does it with both boxes,6A and 6AL, I would suspect a connection outside these boxes, distributor, battery, etc.

carlos_83
03-07-2007, 02:37 AM
how about the module inside that unilite dizzy getting too hot?

Gary Q.
03-10-2007, 06:35 PM
I had a very similar problem on an Accel Dist. and the culprit was one of the wires to the module inside the dist. had the insulation barley worn through, but it was enough that it would intermittantly short and motor would lose fire.

Ernest Hill
03-14-2007, 03:03 PM
My 83 did the exact same thing. The problem was the distributor was beginning to wobble and overheat the points. Got an MSD magnetic trigger distr and it starts and runs great.