I had an experience with an MSD box failure on a trip last summer.The multiple spark only works below 3000 rpm so I was ok on the freeway.I took a 2 lane hwy for a day and my rpms were at 2500-2800.I started to notice the tach spiking.Then the engine died at 55mph.with the auto transmission,it just went to 0 on the tach instantly.Got pulled over,turned the key off then back on and it started back up right away.Didnt have any more stalls in the next day of driving but replaced the box anyway.Apparently it had overheated at the top of it's operating range.

 

Humm Interesting Den...

Mr. Velocity...Did the loose wire damage the box or just crapped out because it finally broke through?

 

Damaged the box. It was a 6M so I couldn't even attempt to open and fix it. The wire was loose on the battery terminal itself.

 

Redid all the wire connectors and replaced a section of questionable wire.

Same problem

This time it remained dead long enough to verify the msd box was getting full power from the ignition lead. Test showed 11.8v to the switched ignition source.

So unless its a broken wire inside the insulation the wiring is good.

Coil or box I guess....


-Gun

 

replace coil...same problem

Replace box...problem gone...so far

So I guess if anyone wanted to know these thing last about 8 years daily driven...at least this one did. Is that a typical life span?

-Gun

 

i think 8 years is less then anyone would expect but more than I would trust it for *g*
hope for you it was the box and you have it sorted!

 

you can bet I "installed" the new box so that it can be removed an reboxed for a return...however I cant imagine it being anything else.

 

Gun Jam, how is your car running now?

I am having almost the same issues but I'm leaning more towards vapor lock. I have a 6AL box and coil on mine.

My car is hard to start, 30-40 seconds of cranking, when warm. It sometimes sputters and dies when I give it gas or start it from a roll. I've since learned what it's going to do and I feather the gas to keep i alive.

I put in a new tank (so that is clean), I replaced all my fuel hose with braided stuff, I rebuilt the carb and then purchased a new one all together, put in a new fuel pump with a filter before and after and also put in a psi meter. It reads 5 when the car is running. I also added a carb spacer. I did this all last weekend.

Car is getting fuel but it's still a bitch to start after its warm and sits for over a minute. Oh and I look at the plugs, they look perfect according to a few plug websites, they are white crowned with the arm thing black. A tad bit lean and running hot I guess, if anything.

I was getting ready to replace the spark wires at least but those are only three years old, my box is four years old. I'm hoping these have a longer life span than four years.

James

 

Its been just fine and the box has been fully installed now all connections have been properly fitted to there respective terminals (not taped on) no more problems ignition wise (it does still lean a bit during easy acceleration but that is cured by rolling on throttle in a very smooth linear fashion (no pausing during clutch release) so Ill do that from now on.

If your issue is the box and your box has the same thing wrong with it the very best indicator is weak spark. The very best test is to remove the coil boot from the coil side and place a grounded wrench 1" from the coil. My MSD box was so weak I couldn't get a spark to jump from that coil at all even when resting the wrench right on top of the coil neck. After a new box it simply jumps to the nearest ground usually over an inch away.

-Gun

 

--> it does still lean a bit during easy acceleration
i remember you have a manifold pressure gauge installed. what's the vacuum reading at that state and what powervalve do you use?