Strange Spark - No Start

GA Wagoneer · Post by **GA Wagoneer** » Wed Apr 15, 2015 8:16 pm

I've been happily driving my jeep vs fixing my Jeep for a little while and just discovered this site! Unfortunately my luck seems to be wearing out and I have a strange problem that I'm hoping y'all can add some wisdom to:

I have an '89 GW w/ a freshly built 360 running a aftermarket (NAPA) Duraspark module (less than 2yrs old), wider cap, new MSD wires, and a few year old aftermarket (NAPA) Ford TFI coil.

Lately I have had intermittent no-start problems, that if I tried long enough would eventually go away and it would run great (ok, pretty darn well). Last week I was driving down the road and the engine suddenly died, but picked back up again within 10-20 second and ran normally after that. This morning it died while running and left me by the side of the road in the rain and late for work...

Now the weird part:
Each time it stayed dead long enough for me to wrench on it, it turned out to be a temporary no-spark condition. I pulled #1 plug and using a remote starter watched for spark while grounding the plug. I first checked all of my ignition connections. Then I began tracing my way back from the plugs through the ignition trying to figure out where I "lost the sparks". What I discovered was that when I pulled the coil wire (coil to dist) and cranked the engine with the plug just barely unplugged, a healthy spark jumped the air gap and the engine turned over every time.

I've had this scenario happen a number of times now, so I've suspected a bad connection between the coil and wire or bad wire, but wiggling the crap out of it has no effect, but pulling it slightly off seems to be the magic bullet!?

Does this make sense to anyone? I've suspected the Duraspark module, but it has the proper resistances when I check it. Could it be my coil? How could I verify that??

REDONE · Post by **REDONE** » Wed Apr 15, 2015 9:00 pm

I think it's your distributor. I know the Duraspark box is the "usual suspect" for intermittent spark as it should be, but something I can't put my finger on says it's your dizzy.

1) Pop the cap and rotate the rotor by hand. See if you can feel any rotational slop NOT associated with the mechanical advance. That would be worn dizzy gears allowing the timing to cause your problems.

2) Pop off the rotor and with just your fingers try pulling up and pushing down on the distributor shaft. If there's more than 1/32 of an inch or so of up/down play, it can have the same effect as worn dizzy gears.

3) Make sure the pick up is screwed down tight and check how close the pick up is to the reluctor (trigger wheel) fins. I don't remember the tolerances but you want it as close as possible without touching.

GA Wagoneer · Post by **GA Wagoneer** » Thu Apr 16, 2015 5:00 am

Redone-

Thanks for the reply. FWIW the dizzy is a year old reman:

1. There isn't any discernible rotational slop
2. The shaft has quite a bit of vertical freedom. I didn't measure it, probably more like 1/8 - 3/16". Although I'm not sure how this will be a problem as the pickups on the cap extend down far enough that the rotor will always be aligned w a contact. Maybe I'm missing your point?
3. The pickup is screwed down tight, but I can jiggle it around and get some movement if I try to by grabbing the sensor itself and lightly pulling-pushing. The clearance between the reluctor wheel and sensor face is very close (few thousandths).

csuengr · Post by **csuengr** » Fri Apr 17, 2015 6:34 am

Duraspark module is dying. They are not that reliable.

Post by **Stuka** » Fri Apr 17, 2015 7:35 am

I disagree on dura spark modules not being reliable. Cheap Chinese knock-offs suck sure. But otherwise they are not inherently unreliable.

It does sound like either the module is dying, or the magnetic pickup in the distributer is going. Although the is less likely with your exact symptoms.

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csuengr · Post by **csuengr** » Fri Apr 17, 2015 8:21 am

OK, so maybe it is the Chinese knockoffs. By the symptoms do sound like a Duraspark. I had to tie cold packs to one of mine one time to get back home. They get hot and quit on ya. Cool off and they are fine.

GA Wagoneer · Post by **GA Wagoneer** » Fri Apr 17, 2015 2:57 pm

The crazy (read FRUSTRATING) thing is that it's been starting and running just fine for the past few days!

FWIW I'm nearly certain that my Duraspark module is from China...

REDONE · Post by **REDONE** » Fri Apr 17, 2015 3:09 pm

There's two fairly straight forward alternatives to the Duraspark box. First is replacing it with an aftermarket multi spark ignition like MSD 6A, Mallory HyFire, etc. The cheaper but more intensive option is called "steal HEI" and is a bit of an arts and crafts project. Nobody I know that has gone either route has made a point of regretting it, I went the MSD route.

Give it a few hours and one of the fuel injection fans will chime in with the "big fix" option of TBI with spark control.

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