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Possible MSD Ignition Issue
I have a Roush 427SR with an MSD ignition system. Today, I inadvertently (stupidly perhaps) left the ignition key on for about 30 minutes without the engine running. Now it won't start. Battery is fine, starter turns it over, just won't start. Anyone know if there is a connection?
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If your battery voltage is below 12.2 V I believe MSD will not fire. Maybe thats what happened.
Brent |
10.6 volts cranking total
Hammer65 if the battery voltage is below 10.6 volts you will not get a good spark and have hard starting. If you left the IGN switch on, not good. Pull the cap on the distributor and check the center post in the cap that it is still there and there are no burnt marks or holes on the rotor. After checking and if everything is OK, put back togeather and pull coil wire fron center of cap and crank motor with good battery on full charge. Leave the wire in the hole and crank you should hear and see the sparking. If it sparks, the msd is ok and the car should start, if not you either killed the coil or cooked the MSD box. There are some test for the MSD in there website for trouble shooting problems. One suggestion, buy and carry enough tools to swap out the box, coil, cap, rotor, or pickup on the side of the road. If you have the extra money get a good used distributor also. One more test, without the coil hooked up, crank the motor and make sure you are getting oil pressure in the motor. After 5-10 seconds and you have none, pull the distributor and check the gear on the bottom. You might have a broken roll pin. Rick L.
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if you take off the cap and you button is flat it is because the rotor bar was not contacting. Make sure you bend your rotor bar up so that when you put the cap on you have to push down slightly to screw down. This will ensure the rotor bar is touching the distributor cap button.
It is also very easy to test the msd box. read the instructions. |
You probably toasted the mag pickup in the distributor. The MSD website has very simple instuctions on how to test it...If it's bad buy 2 and have a spare...
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I agree with Rick. Keep a spare coil and dist (ready to go, with fresh cap) on hand at all times.
That covers all the typical points of failure, from mag pickup to broken gears, corrosion, etc. I almost never see an actual case of the box going bad, but you hear lots of anecdotal stories about them failing. I have a spare one of those, too :) |
Quote:
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How??
How did leaving the ignition on burn up the magnetic pick-up??:confused:
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I checked voltage at the battery and all seems well. The carburetor pumps gas so i tried the following with no results.
Magnetic Pickup Trigger: If you are using the 2-Pin Magnetic Pickup of the MSD to trigger the ignition, follow these steps. 1. Make sure the ignition switch is in the Off position. 2. Remove the coil wire from the distributor cap and position the terminal so it is approximately 1/2" from a good ground. 3. Disconnect the MSD Magnetic Pickup connector from the distributor. 4. Turn the ignition to the On position. DO NOT CRANK THE ENGINE. 5. With a small jumper wire, short the Green and Violet magnetic pickup wires together then pull the jumper off. Each time the short is removed a spark should jump If spark is present, the ignition is working properly. Don't want to have it towed to the dealer if at all possible. |
Questionable MSD Module
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I have had a few MSD boxes burn up over the years, in a few different types of cars. The boxes themselves do not like to be hot. They need good ventilation. I don't know that just leaving it powered up (with the key on), with no air flowing over it, would do it? But, it may be possible. I got pretty good at bypassing the box to see if the box was keeping the car from running. I also started mounting small computer fans on the boxes to help cool them down.
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I just replaced one in my Cobra a couple of weeks ago. I also replced the magnetic pickup in my distributor. Must be the humidity!
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Mounting the MSD box in the footwell rather than the engine compartment really makes the overheating of the control box a non-issue. But, when mounted in the footwell, it usually mounted up-side down; There can be a problem with this installation too if moisture from rain or washing the car can get to the box because there is no drain hole on the top of the box (since it's inverted). Drilling a hole in the top of the box is not an option either because of metal fragments falling inside when drilling. Good electrical connections aside, most MSD problems are related to the manetic pickup or the dist. caps center carbon contact erosion from improper rotor installation.
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Talked to the mechanic who did the install and he knows of a couple of times when customers left the ignition on and, as he says it. "cooked the coil". I replaced the coil and still have nothing. Checked the voltage on the leads going to the coil without them being attached and read 10.6 volts with the ignitoon on.
Next step, talk to him again and see if I can avoid having to take it to the dealer for repairs. More to follow and thanks for the help. |
If the box is new or less than a year old
Hammer65 Send the box back to MSD and let them repair it. You might have burnt out the curcuit board from the heat build up in the capacitors. They stay fully charged with not where to discharge too. If you have a speed shop in the area, go buy another box and hook it up. I welded on my frame of the car without unhooking the MSD box and smoked it. MSD Gave me another new box. I have 2 new ones and a good used one from a swap meet. The distributor is complete and new also. IMO it's better to have this stuff in a tool kit and not need it that be stuck at the track with no parts. Rick L.
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Have you tested the mag pickup? It's a simple resistance test. Just disconnect the 2 wires (noting which is which) and check it...Simple.
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Have you checked by using a jumper wire after disconnecting the distributor? OR have you measured the OHM rating of the module within the distributor? Those two procedures will pinpoint your problem.
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I'm fed up with MSD and their 6A box, which is failed twice in 2000 miles. Box is mounted on the firewall, but both failures occurred when the outside temperature was 75 degrees F. The first time, I merely started the car and backed it out of the garage. Poof! Engine died. The second time, I took it for a short run of about 5 miles. Poof again. This time, I was smart enough to mount some spade terminals so I could switch around a couple wires while disconnecting the MSD black and orange wires. The engine started right up so I could drive home. Maybe this is just a bum box; however, I don't plan on sending it back to MSD again so they can charge me $150 to fix. Are any of the other copycat boxes any good?
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I see and hear of many failures of 6A box in out vehicles. They don't like vibration, heat is secondary. Use the 6T box which was developed for Circle Track Racing and has additional potting within and also use the rubber isolator feet (available through MSD) to assist in mounting and dampening vibration. I've used the same 6T box for 20 years with no issues. (Knock on wood!)
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