…and distributors are wearable parts, it may be 50 years old & not keeping proper timing or advancing evenly.
I had the same cutout problem for months before it was resolved. Please refer to my previous posts.
2800CS engine cut out
- Thread starter Wobdog
- Start date
…and distributors are wearable parts, it may be 50 years old & not keeping proper timing or advancing evenly.
I had the same cutout problem for months before it was resolved. Please refer to my previous posts.
Honolulu
Well-Known Member
Had a BMW K100RS bike that would cut out randomly. Two issues occurred, both were common knowledge among those that rode these great bikes over many years and miles. Their solutions may be of use:
First, I had replaced the ground wire from trans case to battery ground with a heavier wire. One day, playing with it, I noticed that the instrument cluster lights would come on and off if I jiggled the wire at the trans end. Turns out that the wire had accumulated enough corrosion between the strands and the crimped connector, to go intermittent. Fixed that and problem solved.
Second, the connector to the in-tank fuel pump mounts on the bottom of the tank, so gravity and vibration conspired to pull it just enough out of the socket that the fuel pump would quit, and three seconds later, the engine. Replaced the connector, slightly bent the male pins so that there was enough friction, and voila - problem solved.
Hmm.. both cutout issues were electrical, the first ignition-critical, the second fuel-critical. Your sudden cutout would seem to be ignition related, but that it runs a while then dies might be fuel starvation caused by a fuel tank not correctly vented. BTDT, too, with a 2002, when I disconnected/plugged the "extra" tank vent line to "clean up" things.
First, I had replaced the ground wire from trans case to battery ground with a heavier wire. One day, playing with it, I noticed that the instrument cluster lights would come on and off if I jiggled the wire at the trans end. Turns out that the wire had accumulated enough corrosion between the strands and the crimped connector, to go intermittent. Fixed that and problem solved.
Second, the connector to the in-tank fuel pump mounts on the bottom of the tank, so gravity and vibration conspired to pull it just enough out of the socket that the fuel pump would quit, and three seconds later, the engine. Replaced the connector, slightly bent the male pins so that there was enough friction, and voila - problem solved.
Hmm.. both cutout issues were electrical, the first ignition-critical, the second fuel-critical. Your sudden cutout would seem to be ignition related, but that it runs a while then dies might be fuel starvation caused by a fuel tank not correctly vented. BTDT, too, with a 2002, when I disconnected/plugged the "extra" tank vent line to "clean up" things.
IIRC, this is a carburetor car even an abrupt fuel cutoff won’t stop the car instantly, and it would need some time before it would restart and run correctly (time for the fuel bowls to refill).
In contrast, with FI, fuel pump issue would kill the motor within seconds.
OP wasn’t clear if it starts right up immediately or if it needs to sit a bit before it starts again. For me, this is the most important question to start any diagnosis.
Many of the potential failures discussed so far can be eliminated if the car restarts immediately and runs fine right away
My car issue required the car to cool down for 20 min then it would start right up as though nothing was wrong. Interestingly, my 635 would do the same and that turned out to be the fuel pump relay cutting out for no reason.
Part of the reason I got my 2800CS for a bargain price was the fact that it wouldn't run, though it would attempt to start and would sputter on for a few seconds. That, and the rust, but I digress.
I replaced the points with a Pertronix and was rewarded with an engine that would start and run but still would occasionally backfire though the carbs at random times. It was impossible to set the ignition timing because the spark was so erratic I couldn't see the timing mark with the timing light. It was rarely in the window when the timing light flashed.
I've bought refurbished distributor but haven't put it in as the purchase of the car was just on the cusp of moving from Maui to Texas and it ran just well enough to get it on the boat and car carrier for delivery.
But I also found that the wire from the Petronix was a bit too short so that if I revved the engine on its soft engine mounts, it would pull the wire off the coil connection and the engine would stall. But as the torque declined, the mounts would spring back and the wire would touch the terminal again just enough to get the engine to begin to start, but any increase in RPMs would now pull the loose connector away from the terminal, stalling the engine again.
Start, stall, start, stall. Repeat.
That took some head scratching to figure out and of course the first time this happened was at delivery of the car in Austin at a Walmart parking lot, in the freezing rain.
Such fun.
All this will be taken care of when the drivetrain gets reinstalled after rust repair and paint, which is currently on hold pending new garage bay construction. :-/
Carb Backfire.png
lsquaredb
Well-Known Member
If your car still has Zenith carbs and the engine cuts out abruptly when approaching idle, for example when diving up to a stop sign, the problem could be a bad anti-diesel solenoid in one of the carbs. It could also be the wiring connected to the solenoid.
Leonard
1970 2800CSA Bristol
Leonard
1970 2800CSA Bristol
Yes, and the anti-diesel solenoids are an antiquated anti polution device that was specifically designed for the gasoline formulas of the late 1960s and early 1970s. I don't think they are necessary today, but as a start, I would pull them and replace them with fixed idle yet holders. I believe I have two that will fit in place of the Zenith devices.
If the car continues to run, but sometimes diesels, then consider sourcing replacements.