Hot start problems

[party340]

I have a 67 Dart with an msd 6al and a mopar performance distbutor. The ignition will not fire when the car is hot. The starter turns over plenty fast but no spark. If I wait 5 or 10 minutes the car fires right up. Even if you push start the car it cranks up. Its like the starter is sucking all of the juice. I've replaced the coil, wires, and I even tried and digital e curve distributor without the msd box with the same results. The car did not have this problem until I rewired it using a painless wiring harness. Any ideas?

[djswwg]

first thing to check is the gap between the reluctor wheel and pick up coil in the distributor. it should be no more than .008", tighter is better, but BE SURE none of the teeth touch the pick up as it rotates. be sure to use a brass feeler gage, a steel one won't hurt anything, but it's hard to get a proper feel because of the magnetic pick up. second, attach a volt meter to the wire that powers up the msd and be sure it's getting at least 11 volts during engine cranking. those ign. boxes are sensitive to voltage drops, especially during the crank mode. you should see no more than 1/2 to 1 volt difference between battery voltage and voltage at the msd when cranking, if you do, use a jumper from the battery to hot wire the box to see if it solves the problem. if it does, check all the wiring and connections.........................djs

[cudabob496]

had the exact same problem.
orange box to close to header pipes. car would quit
after about 10 minutes.
moved box to cooler area

[peg leg]

And experience says the box is failing under heat. I solved my same problem with a Mopar chrome box.

[70Ted]

pick up coil.

[John Kunkel]

Both the ECU and the pickup in the distributor are subject to failing with temperature.

The next time it has no spark, disconnect the connector at the distributor, turn on the ignition switch and touch the male prong on the engine harness to ground. Each time the prong is grounded and pulled away you should get a spark from the coil. If it sparks the distributor pickup is the problem, if not it's the ECU or coil.

[pishta]

I'm not an MSD fan, 2 left me high and dry on the road to nowhere. I learned after the first and packed the old standby points dizzy in my trunk with a socketed connector to the old harness. I was back on the road in about 10 minutes. Ditto on the voltage issue, check hot cranking voltage to MSD.Heat would be lower on my assumptions as it gets pretty hot while running and it probably never cut out on you. You could experiment with a small motorcycle battery wired in parallel with an isolator switch. Next time it doesn't want to light, swith over to the isolated battery to MSD and when its lit, switch it back. It would be the type of switch that doesn't open between sources but overlaps so you don't lose power when switching. Might be small enough to mount under battery tray and run switch into cab. Get tricky and add a 2nd switch to tie into charging system. Or just go Mallory or Hi-6 digital.

[cudabob496]

I've heard running with a chrome box on a street car is not a good idea.

[party340]

Thanks for the input. Today I hooked up my old orange box and the car ran fine. No hot start problems whatsoever. I've been burned by MSD twice ( 6al and e curve distributor which in my opinion is total junk). I think im going to keep the orange box and buy a rev limiter.

[JVMopar]

I've had my MSD 6AL for 8 years. Never had a problem. I must be lucky.

[dodger1]

My experience was a bad pick-up coil in a re-man Mopar electronic dist. That was found after changing out the orange box for the old stock one, plus the cap and rotor. I have since installed a Mallory box (similar to MSD 6) and have not had any further issues. That was about 9 years ago - (Mirada 360 headers etc.)

[cudabob496]

Not sure if there is anything better than MSD? There may be some equal to MSD.

[Green66]

I have always had great luck with MSD. I did learn the hard way that Voltage Drop while cranking will cause the box to not fire. Usually it will fire once or twice once you quit cranking. I believe it has to have 10.5 volts to fire. I tested for a voltage drop on my car and it was pulling down to slightly under 10 volts while cranking. I had to install heavier battery cables, especially since my battery is in the trunk, and make sure that you have at least a 10 gauge power feed to the MSD box. After i did all this i had no hot start problems with my MSD. Oh by the way if you are dead set against using your 6al and you want to sell it cheap let me know.

[bulldog426]

i've had experiences with the control module getting hot, and not sending fire, maybe your box is getting hot?? either from the engine temp, or from something electrical?

[cudabob496]

Originally Posted by Green66

I have always had great luck with MSD. I did learn the hard way that Voltage Drop while cranking will cause the box to not fire. Usually it will fire once or twice once you quit cranking. I believe it has to have 10.5 volts to fire. I tested for a voltage drop on my car and it was pulling down to slightly under 10 volts while cranking. I had to install heavier battery cables, especially since my battery is in the trunk, and make sure that you have at least a 10 gauge power feed to the MSD box. After i did all this i had no hot start problems with my MSD. Oh by the way if you are dead set against using your 6al and you want to sell it cheap let me know.

Having a large grounding wire from the engine to ground is also a must!

[GEORGE68HEMIRR]

i agree with what everyone is saying.....nothing better then MSD....you box is too close to the heat.....move it inside your car....problem fixed....msd even tells you that