Exhibit A – A completely clogged accelerator pump. The Solex C35’s accelerator pump is the lowest point on the carburetor, just like a Weber DCOE, and it therefore acts a collection tank for rust and debris that find their way into the float bowls.
We tore these carburetors down and placed them in the sonic cleaner for an hour or so with a very mild cleaning solution. This car is a driver. We then installed a rebuild kit with all new accelerator pump components, gaskets, o-rings, and more.
The real culprit. This fuel tank had likely never been out of the car. And, after getting it back from the acid dipper, we tried a number of methods to clear out any remaining rust or debri without success. Ultimately, an access hole had to be made in order to remove the clogged fuel return line.
After desoldering the old line and removing it through the aforementioned access hole, we bent up a new line, and reinstalled with a small sheetmetal bracket to keep it place. The access hole was TIG-welded shut, and an ethanol-safe coating was applied to the tank.
Welded back up, epoxy-primed, and painted flat-black on the outside.
This is the bronze fuel tank collar found on S1 and S2 Fulvias. The S3 cars received a plastic locknut (blame Fiat) and it is only a matter of time before it needs to be replaced, if it hasn’t already. These bronze ones are readily available.
In order to change the locknut, the gas cap retaining flange will need to be removed and re-soldered back on.
Nice new fuel drain plugs are available in two different thread pitches, they also double as the fuel pickup filter. The original mesh is typically damage or clogged with years of gunk.