Another MSD Ignition Problem Solving Question!!

[antares]

OK. I have a MSD 6AL installed in a SC 3.0. It was running when I shut it off last night. this morning it would not fire.
Here is what I have done.
1) tested unit by jumping purple/green wire to fire coil wire going into distributor cap. OK I get spark.
2) Connected coil wire into cap. Removed cap and jumped wire from inside cap to ground. OK I got spark.
3) Yes I am getting power to the MSD Box since I checked for 12V current to the small red lead into the box which is connected to my ignition switch.

Now unless I am missing something here in my thought process: If I am getting spark when I jumper the purple/green MSD leads It would then follow that it would route to the rotor and down the wires to the spark plugs. However, this only happens it would appear when I jumper the MSD box to create spark. Apparantly when everything is buttoned up and i turn the key i am not getting spark to the plugs. It seems to me the purple/green tied into my magnetic sensor/ground is not sending the signal to the MSD box to fire even though when i physically jumper it the hardware/equipment will fire. I just cleaned the connection from the distributor green wire and shield and put this all together over a year ago when I stored the car and it was running great. It started yesterday and ran but would not idle and would pop occasionally through the intake at 1000 or 2000 rpm but would not idle. Same condition as a year ago that prompted me to get back into the green distributor wire and rehook it back up. Perplexing ????
Question: How can a physical enity (a spark)and associated distributor wire and connections operate the day before and not operate 8-hours later ?? I have been on this mary-go-round before. If you are getting spark when jumpered from the purple/green that does not mean the distributor is sending the signal to fire. I do not remember how I fixed the problem.

Any input at this point would be helpful. How do I test to see if the distributor green wire with outer shielding is sending a signal to the connected purple/green wire of the MSD when not being jumpered ??

antares
fatnwide

[lateapex911]

Before we get further....are you sure you don't have spark??? Try pulling a wire, hooking up a plug and grounding the threads, then cranking. If you see spark, you know that's not your problem.

[Early_S_Man]

The magnetic pickup assembly should have a resistance of 600 Ohms, +/- 10% at room temperature. Disconnect green cable from MSD wires and measure the resistance back through the green coax cable towards the distributor and pickup coil with digital multimeter set on 2K Ohms range. Leave test leads connected and set multimeter to 20 Volt AC range ... crank over engine and look for 1 - 3 Volt trigger signal. NAPA sells a replacement pickup assembly for around $30 ... if your tests are indicative of a bad pickup coil.

http://www.napaonline.com/masterpages/NOLMaster.aspx?PageId=470&LineCode=BA&PartNumber=1800144&Description=Distributor+Pick-Up+Assy



The electrical connections in your engine compartment go through a heat cycle every time your car is used. Expansion and contraction occurs every time, and any corrosion present may cause a change in the connection when the connectors cool down from normal operating temperatures!

[antares]

Early S Man - now when you say connect to the green wire to test for ohms do you mean at the connection where the green/purple terminal connects to the MSD box? I connect my red lead to the green wire and the black goes where? set meter ohm at 2K or 2M ? could you walk me through this so i get it right.
thanks in advance.
antares

[Early_S_Man]

Use the 2K Ohms range. What you want to test is the wires and green coax cable to the distributor and the pickup assembly inside.

[antares]

Early S Man - yes thankyou. you are the man.
with this information i was able to correctly trace out things. i have impulse and spark. i found a connection on the old cd main connector that was questionable. fixed it and it started. but kills. if i spray starter fuild into the popu valve it runs but only for a about 15 seconds. i am now going to check fuel pressures of the fuel pump and at the fuel distributor control valve.
thanks again.

antares
fatnwide

[john walker's workshop]

not helpful, but i always wonder why folks remove a perfectly good and superior factory ignition system and install a MSD.

[Shaun @ Tru6]

Originally posted by john walker's workshop
not helpful, but i always wonder why folks remove a perfectly good and superior factory ignition system and install a MSD.

John, would you say a factory 69E ignition system is superior to an MSD set-up?

[john walker's workshop]

i'm talking CD systems.

[Shaun @ Tru6]

Good to know, thanks.

[antares]

Well actually in my case my old cd kicked it so i went with the MSD. the only real problem with the MSD is if you have any weak component(s) outside of it like the distributor or coil or wires the problem will be magnified. but i have been happy with mine up to now.

as for my starting problem i discovered that i had not fully torqued the 3 screws on top on my fuel distributor. i did that and the car runs better but still seems to be missing like bad gas. so i removed the plugs (new) and gapped them from .050 to .045. also removed the 4-gallons of gas which was fairly new and replaced with new gas. no difference here. i will pull the distributor and see if the connector pongs on the pickup are corroded. that happened once before just from sitting even without a battery in the system.

i will get back to here when i cure the eratic run problem.

antares
fatnwide