There was a service bulletin for a similar problem that applied to my 1980 Volare. The symptom was a long crank time, but once the engine started, that long crank time never showed up during the rest of the day. Next morning would be the same long crank time. The cause was determined to be gas was vaporizing in the float bowl and going into the charcoal canister. The fix was to add a small check valve in that hose. I found one of those at a salvage yard, but I never installed it on my car.
What might be related to your problem is I purposely ran my car out of gas on multiple occasions, then added a measured gallon, to figure out what I was getting for fuel mileage. (28.3 consistently in warm months for a 4,000 pound car with steel bumpers). I found the fuel pump would not draw gas from the tank at the relatively low cranking speed. I always had to dump a little down the carburetor. Being a slant-six, the intake runners were too long to cause flooding, so the engine would run as much as three or four seconds on what I dumped in. Often I had to do that twice, but that higher speed would get the gas flowing from the tank. Once the steel line and float bowl were filled, the engine ran fine after that.
When emissions systems are mindlessly removed, we have to consider the effect on the related systems. On older cars, the float bowls were vented to the atmosphere, but they were larger and held more gas. Even though some evaporated, by the time the engine cooled down, there was still enough in there for the next start. What I would look at first is what is happening in the float bowl when you stop a hot engine. If the vent hose that went to the charcoal canister is hanging loose, gas is going to evaporate, possibly leaving you with the same problem I had. If that vent hose is plugged, the expanding vaporized gas needs a place to go. Pressure building in the float bowl could force the gas through the jet, then into the intake manifold, resulting in flooding. To identify that, hold the accelerator to the floor in "clear-flood" mode, and see if the engine starts faster. I would suspect you would smell that gas too.
To drill the passages in the bodies of the carburetors, they drill from the outside in multiple directions from one starting point, then they seal the starting hole with a soft metal plug, or cap. GM had some trouble around that time with those plugs working loose and leaking. Those plugs were always on the bottom, so the gas leaked into the intake manifold, not outside. The fix for that was to empty and dry the carburetor, clean the area around those plugs, then seal them with a layer of epoxy.
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Thursday, March 25th, 2021 AT 4:45 PM
