MSD - No spark while engine is hot

datsun280z · #1 (**permalink**) 04-29-2015, 02:59 AM

Hello
Strange problem... while engine is cold it start's right up.. on
first etempt..
When engine is shut down ( after 15 or more minutes ) and i want
to start it it won't start..
I checked and saw that no current comes to the distributor...
MSD 6
Is the Ignition box defective ?
Can it be something with the wiring harness ?
Thx

Gaz64 · #2 (**permalink**) 04-29-2015, 03:11 AM

Do you know how to test the system for spark, engine not running?

What wire do you trigger with? White only (points), or green and purple (mag pickup)?

A common problem is the magnetic pickup going open circuit when hot.

What engine? What distributor?

Tommy · #3 (**permalink**) 04-29-2015, 04:10 AM

Datsun280Z,
What you described is the exact symptom of my failed MSD 6AL. I sent it back and they fixed it for a fee.

JLip · #4 (**permalink**) 04-30-2015, 01:23 AM

Sorry to say....I took out the MSD box and my car runs MUCH better.

Ron61 · #5 (**permalink**) 04-30-2015, 03:12 AM

Jlip,

I had a very similar thing happen to one of my cars. After it got hot it was hard to start and just ran really bad. I disconnected the MSD unit and I hadn't gone 50 feet before I cold tell the difference. I think the heat caused a failure in mine as I never bothered to contact them to see if they would replace it. I went to another brand and have been much happier with it. I think MSD quality has gone way down in the past few years.

Ron

lovehamr · #6 (**permalink**) 04-30-2015, 05:11 AM

Ron, what ignition are you using now?

Chachi427 · #7 (**permalink**) 04-30-2015, 06:29 AM

I had the same issue and it was my magnetic pick up. Check the continuity across the pick up when warm and cold. If it reads greater than 1K ohms then I would first replace that. Only about a $40 fix.

zrayr · #8 (**permalink**) 05-01-2015, 10:46 PM

Quote:

Originally Posted by Chachi427

I had the same issue and it was my magnetic pick up. Check the continuity across the pick up when warm and cold. If it reads greater than 1K ohms then I would first replace that. Only about a $40 fix.

the pick-up will read differently (more resistance) when hot. but the critical reading is less than !,000 ohms I believe. Check with MSD on that. Also. it does help to have the box in a "breezy" area if located under the hood. I like to put them under the dash when possible.

Z