This has happened the last 3 times I’ve taken my Cat out. After a long period of not driving it when I finally get fuel to the combustion chamber the car runs maybe on 6 cylinders. First thought is flooded. I try to drive it a mile or so and give up parking it back in the shop. After 15 minutes or so it fires right up no miss and runs hard as it should for the rest of the adventure. The first time it happened I pulled the plugs thinking they might be wet from fuel but that’s not the case. In 50 years of toying wiith cars I thought I’d seen it all. This one has me baffled.
Any thoughts would be appreciated.
I have no choke hooked up and the butterfly is open. At operating temperature it still runs ratty until I let it set for 15 minutes or so. Still might be flooding out but the time I pulled the plugs none were wet.
Sure sounds like the gas has gone bad and it may be causing stuck valves and / or carburetor issues. When gas goes bad it’s time to drain it and clean everything in the fuel system. While the alcohol based fuel is terrible, regular gas can and does go bad too if given enough time.
Thanks for the reply’s. I will drain and replace with new fuel. There is no backfire or smell of raw gas or smell of a rich mixture. Maybe I can employ my engine analyzer but that could take some time. HaHa.
About 3 months. Early spring but just for a mile or two. Had to turn back home because was worried of washing out the rings even though I don’t believe it is flooding and fouling plugs
I do have an Autolite 4300 on my other Cougar that works great. Maybe I will do a swap and see if I have the same issue. That could narrow it down to carburetation or mechanical
Yes, when my mechanic couldn’t get mine running right after engine overhaul, he borrowed another 4300 carb from his friend’s car. The sediment in my fuel system quickly plugged it up too. My car didn’t run any better, so he didn’t prove anything. And he plugged up his friends carb in the process.
Might want to look at the supply side of the fuel system. Potentially a bad hose at the tank or fuel pump starving for fuel. Could also look at the fuel filter, PCV and lines, etc. I actually had one filter plug on my own car when it was carbed and sat for the winter, it varnished and it ran, but I couldn’t blow through it.
Could even look close at the ignition and see if it is doing something funky, I’d start with making sure the advance plate moved and the spark was good and blue. Lots of basic troubleshooting is likely best
The settle and run well results don’t really make sense for a carb. If it was that full of sediment that it could block an IFR, main jet or PVCR, it wouldn’t correct itself.
Totally agree with that. As they say, “carburetor problems” are typically electrical in nature. Lots of carburetors get replaced because the owner doesn’t know how to check and adjust the ignition system.
I’m beginning to wonder if maybe fuel supply. Even though my fuel filters look ok maybe something in my tank is clogging the pickup. Time to pull the tank and take a peek out of curiosity since I’ve only had the car 3 years and haven’t got around to checking things out.
Or maybe take a peek inside the tank before you pull it by removing the filler hose. If no rust, you might get by with draining and refilling with fresh fuel. I do agree with My427stang on the sediment in carb though - it wouldn’t clear up after sitting for 15 minutes. It sure could be an ignition problem, but you will need clean fresh fuel regardless.
It could possibly be the ignition. I’d most likely consider the fuel as a potential cause. Another is the possible decrease in manifold vacuum with an aftermarket camshaft. If vacuum is too low then the fuel may not be atomizing properly on the idle circuit beneath the throttle plates. The fuel will be instead condensed and collecting on the floor of the intake if that be the case. This can cause the plugs to become fouled. Try adjusting the ‘idle air bleed’ and ‘idle feed restriction’ on both the primary and secondary sides in order to get the fuel to spray if that be the case.
