69 W200 New Ignition Coil-Runs rough, sputters, gas smell

[CW200]

Hello,

For the past year I have been working on a 69 W200 with a lot of help from the this site. I got the truck running reliable (6 months no problem) until a few weeks ago. Between 2,000 and 2,800 RPM the truck would sputter, misfire, run rough, ect. The RPM gauge would bounce around. Below 2,000 it ran fine and over 2,800 it would run fine, although 3,000 RPM seems to be the max it likes to run continuously. After some research, I thought a new ignition coil could solve the problem. Replaced the coil with the identical coil on the truck, and now it runs rough, sputters, smells of gas at all RPM ranges. Its so bad I didn't want to take it out of the garage. It doesn't seem to be getting spark at all cylinders.

Things I have done:
Check voltage at coil with key on= 5.5 volts
Ballast Resistor ohms = 1.6
Plugs are new
Wires are new
Verified the coil was wired correctly
Thought timing might need to be adjusted, didn't help.
Coil is Standard UC-12 same as I took off.

I have not put the old coil back on, although i plan to to see if that at least resolves the issues at idle and low RPM. The ignition system appears to be stock and everything seems to match my FSM.

Thanks for any help in advance!!!

[Hobcobble]

Have you ever replaced the accelerator pump in the carb?

John

[CW200]

I put a remanufactured 1968-1969 Dodge Truck Manual Choke Stromberg WW Carburetor (2 Barrel) on it in June of 2021. I purchased it from Carburetor Center in California.

Thanks Chad

[PwrWgnDrvr]

Strong likelihood the distributor shaft and bushings are worn. That allows significant side play on the shaft which causes erratic point dwell and spark.

[CW200]

I put a new distributor on in May of 2021, can they wear that quickly? It was a Spectra Premium Distributor Part #CH05

[BigBlockTrucks]

It shouldn’t wear that quickly.
Was the replacement distributor new or remanufactured? It is possible that they didn’t put new bushings in it. Kind of like a poor rebuild on a carb. I have seen plenty of cheap rebuilt carbs that still had play in the throttle shafts causing a vacuum leak.

[CW200]

It was brand new. Others have mentioned a vacuum leak as well. I plan to put the old coil back on tonight just to see what happens.

[BigBlockTrucks]

With a quick search on google you can find the directions to test your coil. You will need an ohm meter.

[CW200]

I tested the old and new coil, the readings were identical. 8,960 ohms and 1.9 ohms….I guess I messed something up installing the new coil.

[jeffc57]

ARE YOU STILL RUNNING POINTS? possible cap and router issue ??

[CW200]

Yes am still running points. I have been considering movie to a electronic ignition kit. There are just so many out there.

[Jim100]

Did you replace the distributor to try and fix the issue? The poor running was with both the old and new?

[CW200]

The poor running was with both the new and old ignition coil. I will look into the distributor.

[58pwrwgn]

Try removing/replacing the condenser

[martincom]

Which side of the coil did you measure the 5.5 volts w/key on? If on the positive side (feed from ballast resistor/start circuit), it seems awfully low. If from the negative side, it should be zero when the points are closed and battery voltage when open.

Please re-measure, w/key on:

1. Voltage on positive side of coil.
2. Battery voltage at starter relay.
3. Voltage on both sides of ballast resistor.

Connect the ground lead, of your voltmeter, to the engine block when making these measurement. Report back with your findings.

I'm going to speculate you have a voltage drop issue. It could be in a number of locations and may not be limited to just one. Typical problem areas are the clamp on battery cable repair post clamps. The battery cables corrodes between the wire and the clamp. The battery and alternator bulkhead connectors are another problematic connection.

[CW200]

I will take all the measurements after work.

I took the coil voltage last night. It was 5.5 volts on the positive terminal with the key turned to on position. I unplugged the ballast resistor and measured 12.34 volts at the terminal.

I did not measure the voltage drop over the resistor. I need to measure the voltage at starter relay. I have read some posts saying you should have 5 volts at the ignition and then others saying 9 volts. I have also read people debating whether the resistance should be .6 ohms or 1.6 ohms. My FSM says .6 ohms but I measure close to 1.6 ohms

[Kaegi]

have you checked the dwell with a dwell meter? then check timing.

[CW200]

I have not checked the dwell, in fact had to look that up.

So I went ahead and swapped out the points distributor with an electronic ignition over the weekend. I live close to a summit racing and they had mopar kit in stock. It completely solved the problem I was having. The truck runs smooth through the entire RPM range. I didn't mess with the springs for the mechanical advance. Instructions said the stock configuration works for most scenarios. I set the timing at 5 BTC (FSM recommended idle timing for 2 barrel carbonator). This seemed to work well.

The timing did jump a little, mainly between 5 BTC and 0. Maybe a timing chain, I'm sure it has never been replaced.

Thanks for all the help!! I have learned so much from this forum.

[martincom]

Good to hear that took care of your problem. The kit you utilized is a good way to go. I found, with today's fuel, being a bit more advanced on initial timing worked better for me. However, if you're happy with the way it runs "If it ain't broke, don't fix it."

I'd still look and make sure you don't have a voltage drop issue. Electronic ignitions do not like low voltage. while the present kits are a bit different than the production Chrysler Electronic Ignition, the production units would miss when the voltage become low.

[jeffc57]

be sure to run a ground wire from the ECU mount screw to negative ground battery cable, is is the most common issue with this set up is a good ground of the ECU, often fine when hooked up, but with time often happens that the box will loose a good "body" ground