Duraspark - Second Opinion

Yes I know that the general rule is if in doubt swap it, but here's the issue:

I was having strange miss issues in late winter that I partially suspected was the original module either failing or poor connections because the plastic connectors had crumbled and everything was just pins pushed into sockets so I switched it out for an SMP LX214 (DS2 Yellow grommet with 3 connectors) and changed the coil with a used but known good one because I found it was weeping oil out of the secondary output tower. Immediately took it on a 1200km road trip and had no issues.
The car was parked for most of the spring and early summer for engine work and was fine when I got it back on the road again until about a month and a half ago. I was driving home (probably unrelated but that night there was a pretty nasty thunderstorm I had gone out to photograph and I got one heck of a trophy photo of a bolt so damn close it had me ducking for cover inside the car) and the engine dropped dead when I was heading back to safety. Pulled over, started on a bump of the key and idled fine in park/neutral but twice I would put it into any gear and would instantly die. Third time I bumped the key, revved it for a few seconds and then it was okay going into gear, only to have the engine die a few minutes later while driving and before I could pull over the engine came back with no hesitation or lack of power. Classic sign of module failure, but the module wasn't overly hot.
Thought nothing about it again until in the middle of last week I caught it erratically revving. The computer is both solenoid and vacuum kicking the idle like its unhappy about something. I had it in the driveway during one of its fits as I was looking for tools to investigate further and on its own the engine again dropped dead and again, the module wasn't hot or anything and started again with a bump of the key. I've been planning to do a full sensor, harness and computer test later this week when this morning I'm driving to work and again the engine dropped dead, I pull over and it starts again no problem with a bump of the key. No problems the rest of the trip.

Those SMP modules suck and they're $80 each before shipping, hence my hesitation to buy another one when this one is not even six months old. Because this is an '82 the computer doesn't intercept the tach signal going to the coil (so we can't immediately blame the computer for the weird idling and the engine dying for no reason) but you can't just swap in a blue grommet module because the computer needs that extra connector for spark retard control, and I got a small stack of those used and 80's Echlin NOS.

Gut instinct: Change the module. Do my observations agree with that?

Problem found was a cracked fuel suction line to tank. usually had enough fuel to idle but sucked air as load stepped up. Restarted like a champ and sometimes stopped on road for no reason. as the engine flexed in mountings and underhood temperature changed crack would open and close enough to suck air rather than fuel. Just be sure you have fuel before full blame on the ignition.

You might be onto something. I purged the line, disconnected the tank and the fuel pump, plugged one side and put a hand vacuum pump on the other. Initially I had leaks and it looks like the fuel filter I installed before the fuel pump is starting to crack, so I'll replace that tomorrow. Checking form the other side of the filter I found no leaks, so the fuel pump would of been constantly fighting a fuel filter that was mostly full of air but the hoses and the steel line are good.

Have you replaced the pickup coil in the distributor??? I'm guessing the 6 cylinder Duraspark uses a pickup coil like the V8 system does. There are ohm tests you can do on the pickup coil, between a few of the wires. I forget which wires & what the readings should be, should be easy enough to find with an interweb search. If the pickup reads good, heat it with a hair drier & see if the readings change.

I have not replaced the pickup but yes I believe it's the same, just with a six point reluctor. Testing cold I get 680 ohms across the pickup coil. On a hot engine it's 720 ohms. The interwebs says both readings are okay.

OP, have you inspected the distributor cap? A cracked centre terminal could be your culprit.

Yes. It looks good. I replaces the cap and rotor in March so they are also still quite new.

Alright I'm going to carve up one of my more abused blue grommet modules and steal the connectors, then I can swap the original module back in.

Edited by MIPS - Sep/12/2022 at 11:25pm

Problem solved. My bad.

I had installed a connector (crimped and soldered) after the ignition module but before the rest of the car for a knock sensor and anti-theft system. I thought the ignition system only needed one or two amps but it looks like it wants a lot more and the connector has burned up, causing a intermittent fault.



I'll replace it with a better connector but as a newbie here how many amps should I expect on the TACH wire?