Car was running great, then I was checking things over under the hood before our club cruise, and I noticed the bracket that had been holding the ignition coil to the fender had come loose, and the coil was just hanging by the wires. I found a new bolt to mount it back in place, and the car ran ok for the 60 mile trip that evening but it started developing a bit of a surge/hesitation under light throttle.
The next day we had our club cruise. The light throttle issue was more pronounced, but it wasn’t serious yet.
Drove the 60 miles back home on Sunday, and it got much worse. The car was lagging and hesitating very badly from a stop to the point that I was worried about pulling out into traffic. If I was coasting at 65mph on the highway, then started the accelerate again, the engine would bog and stumble before eventually catching up with itself.
By the time I got home I was getting popping noises when I let off the gas to slow down for a stop sign or stop light.
My first thought was the coil since it had been hanging and banging. I put a new one on tonight. The car ran ok cold with only the slightest hesitation, but as it warmed up, the other issues started coming back.
Due to the popping on decelleration, I assumed the unburned fuel meant this was an ignition issue. Would that be a correct assumption or could that still happen with a lean fuel situation?
My plugs all look good, so I guess next step is check plug wires and check the pertronix. Any other troubleshooting suggestions?
I think sfhess is probably right. Look for hoses with problems, and don’t forget to check your PCV valve. If that sticks open, your engine is sucking a LOT of air out of the valve cover, and that one is a hard vacuum leak to find. Too lean can mean unburnt gas in your exhaust because it didn’t ignite in the cylinder properly, and that can cause some of the popping you’re talking about.
If you’ve chased down all possible vac leaks (under the carb, along the intake gaskets), and that’s not it, your ignition timing may have slipped, or there could be a problem with the dizzy. (not cam/valve timing. When that ‘slips’ your engine will just flat out die, not run rough.)
With the timing too far retarded, you’d be down on power, and you’d get a lot of pops and backfires because of all the unburnt fuel/air in your exhaust. It’ll also make your exhaust manifolds very hot.
One last and very obvious/simple thing to check: is your choke fully open when the engine’s warmed up? If that’s sticking, your car might run okay when cold, but after that, it will stink up the whole neighborhood with unburnt fuel. It’d run rough, possibly wanting to stall, and backfiring too. With it being way rich from the stuck choke, you don’t usually get the lean ‘cackles’ but more deafening explosions every once in a while that threaten to blow out your mufflers.
Has anyone told you guys how incredibly smart you are lately? It was a stretched vacuum cap on the carburetor. They had both looked fine when I inspected them previously, but I went and bought some fresh ones tonight just to make sure. Problem solved.
I really appreciate it when you guys point me back in the right direction. I was already down a coil and a fuel filter, and I was about to go buy all new plug wires.
On the upside the PCV system has been thoroughly cleaned as well.