by Eric Gibeaut in the January 1996 RootesReview
Chances are, the accelerator pump diaphragm has dried-out during storage. This is hard to diagnose as it appears to be an ignition problem so after you check the entire ignition and replace questionable parts the problem is still there! Don’t ask how I learned this.
An Alpine will display similar symptoms. Series V Alpines will give the same symptoms if the dashpot oil is of the wrong viscosity or if it is dry. Of course this info is for Series V owners with the Stromberg carbs which don’t have accelerator pumps.
If your Sunbeam has been stored for more than about six months, especially if the gas tank was not completely full, the gas may have turned bad. If the gas has a sweet varnish smell to it, you must drain the tank and try some fresh fuel. The carb will probably have to be rebuilt too.
How to prevent all of this? Drive ’em!