no spark again

judgemint · #1 04-03-2013, 02:35 PM

everything has been replaced. starts up runs fine but after you shut it off no spark?? 74 f 100 4x4 390. msd dist and 6 box. I shorted out the system with the paper clip, the coil wire was shooting spark just fine, so is my problem in the dist?? I wanted to do an ohm test, on the pick up(wires spliced in to box wires via electrical connectors) put probes to dist wires didn't get any reading I read that The resistance should be within 500 - 700 ohms. will it not show me a reading touching the 2 wires?? could my pickup be bad??

Gaz64 · #2 04-04-2013, 03:53 AM

Sounds like the pickup coil is o/c.

Let it cool down and retest the pickup resistance.

msdtech22 · #3 04-04-2013, 07:22 AM

Usually when we experience issues such as you describe, the pickup in the distributor is the culprit.

If the distributor is a two wire MSD Distributor, the replacement part number is PN 84661 and can be purchased at your local MSD Dealer.

Here is a link to find a dealer: http://www.msdignition.com/zipsearch.aspx

I have attached a document explaining that replacement procedure.

Lazarus · #4 04-04-2013, 10:43 AM

As of 10/12 you installed a new distributor, but your symptom did not change. How did you get it running for 6 months?
You say that when you shut it off, it does not start. Do you mean you are trying to re-start a hot engine, or a cold engine?

Everyone seems to believe that changing the pickup will solve the problem. I have to ask what is the reason that the MSD mag pickups have such a high failure rate? Maybe it would be a good idea to have the customers return their "faulty" pickups to determine what is happening.

-L

judgemint · #5 04-04-2013, 01:21 PM

i haven't driven it. its been in the garage, just haven't had the time. yes the engine is hot when i try to restart it. I will have spark shooting from the coil wire but no spark coming out of the plug wire. ohm test to pickup before starting was .580 and after it wouldn't start was .682 ???

msdtech22 · #6 04-04-2013, 02:37 PM

When you see the spark 'jump', are you cranking the starter or are you doing the false trigger test as was outlined in that link?

If you are cranking the engine, you don't get any spark jump at the plug end of the wire when laid near a ground. Is that correct?

judgemint · #7 04-04-2013, 06:02 PM

yes, false trigger test, I have spark out of coil wire. Cranking starter I have no spark at plug

msdtech22 · #8 04-05-2013, 07:00 AM

When doing that false trigger test and checking for spark at the plug end of the wire, you first need to 'bump' the starter and align the rotor under the cap with a pole on the cap. Once that alignment is made, replace the cap. Follow the wire that the rotor aligns with and follow that wire down to the spark plug.

Remove the wire from the plug and place the spark plug end 1/4 to 1/2 inch from a good engine ground. Turn the ignition 'on'.

DOT NOT CRANK THE ENGINE

Perform the false trigger test.

See if you get spark from the wire then.

If not, where is your engine grounded?

I ask this because if you get spark out of the box, the box is working. Now we need to find out why he spark energy isn't getting to the end of he plug wire.