Well I had my 72 Cutlass (350 4bbl quadrajet with HEI distributor) out yesterday and as I pulled into a parking lot the engine shut off with no notice at all. Attempted to restart and crank but would not start. First thing that came to mind is the ignition module. Luckily I was prepared with an extra on hand. I swapped it out and with the first crank it still didn't start. At this point I was beyond frustrated. Took another look under the hood to make sure I reconnected everything and then took another shot at it and it fired up and was running. Well after driving for a bit i began to notice a hesitation and bucking. This was not there prior to the stalling issue. I removed the distributor cap today and noticed that one of the wires from the pickup coil to the module was open and not insulated. I put heat shrink over the open area to insulate it until I replace the pickup however I am stumped at the bucking issue. I am not sure if the wire was damaged prior to the stall and I actually put the original module back in and the car starts and runs fine with the exception of the bucking so this concern is there with 2 different modules. Could it just be a coincidence and I have 2 totally different issues? Would the open wire cause a stall? Strangely enough the bucking seems to happen after the vehicle is warmed up and between 40-50 mph. It seems to be good prior to 40 and then you can drive through it and it gets better after 50. I plan on removing the vacuum from the distributor advance to see if that helps. My second thought goes to the accelerator pump. The carb was rebuilt 2 years ago and I mostly use ethanol free but there are definitely times when I have to get regular 87 fuel. Any other thoughts or steps I should take to move forward on diagnosing this issue?

Mike

 

Yes it can be the pole piece/pickup coil. It should measure 500-1500 ohms across the two wires, lightly wiggle the wires whilst checking, wiggling the wires shouldn't change the ohms. Try disconnecting the vacuum advance, if the problem goes away it is the pole piece wires.

 

I had low speed bucking with too much vacuum advance. I dropped from 30 to 20 degrees, problem went away.

 

Thanks for the replies. I will take it for a ride with the vacuum advance disconnected before I install the new pickup just to see how it runs. Either way the pickup needs replaced so we'll start with that and diagnose deeper if needed. I had to order it online so I need to wait for it to arrive before I dig in.

 

The gear has to be removed on the distributor to do this. When reinstalling the gear the dimple on the side of the gear should point in the same direction as the rotor tip.

 

Well the pickup coil finally showed up and I got it installed. Replaced fuel filter while I was there (both inline and carburetor inlet). It started and ran great in the garage for about 15 -20 minutes. Took a dinner break and then drove it. After a few minutes I began to get a stumble so I turned around to come back home and unfortunately it died and wouldn't restart. Since I was on the path of spark I swapped out the module again and still nothing. Checked for fuel in the carburetor and I did see a stream of fuel when hitting the throttle. At this point a couple of nice guys across the road came to give a hand. It would run on starting fluid so that rules out the spark. Unfortunately we couldn't get it running to drive it home however they did offer to tow me back as I was only a couple miles or less away. Back to the drawing board to test my fuel situation. Either way that pickup needed replaced so at least I don't feel bad about that cost lol.

 

Had the opportunity to get a deeper look. First thing I checked was fuel pressure and unfortunately I had nothing coming out of the pump. Replacing the pump and strainer. Thankfully I thought about the strainer...this one is long gone! Slightly bummed I did all this and didn't find a build sheet.