Readers may remember that this blog has contributed significantly to vehicular progress with ground-breaking theories and public policy (see Classic Velocity Laws, the Theory of Concentric Circles, and the theory of Eminent Domain). In that continuing vein (pun intended), we offer the Theory of Petrosclerosis. Since the beginning of the internal combustion engine, no one has been able to avoid sending fuel through a relatively narrow passage into the cylinder. Actually, I take that back. Some of the earliest vehicles just dumped fuel into the combustion chamber by the bucketload. However, half of this fuel came out the exhaust unconsumed and burned down everything in the vehicle's wake. This in turn left charred remains behind, and hence the name the Black Forrest. But I digress.
1. Rubber fuel hoses were cheap, flexible, and intended to be replaced frequently. They constrict internally where it is impossible to detect. Although they can look and feel fine externally, they can be closed and rock solid inside.
2. Metal fuel lines are subject to buildup of deposits over time. This happens internally where it is impossible to detect.
3. Fuel filters are designed to trap particles and contaminants, and to become blocked. They are generally invisible while operating the vehicle, but blockages can be clearly seen once stranded on the side of the road.
4. Carburetor jets are subject to blockage by small particles and deposits over time. They are already invisible without disassembly, and their blockage is invisible as well.
5. Fuel pumps generally have a screen or filter. See #3 they also have narrow metal passages designed to build pressure. See #2. They are sometimes invisible and submerged in the fuel tank, which almost always has sediment and other blockage-inducing material (plaque) awaiting an opportunity.
6. Fuel injectors generally require higher pressures and have even narrower passages than carburetors. See #4. They are generally accompanied by a fuel distributor or some other complex pump tied to engine timing. See #5 on steroids.
7. Petcocks have screens and narrow passages. They are usually at the bottom of the fuel tank, and readily collect the contents thereof. Their demise is invisible, and the remedy usually involves you getting at least one full appendage drenched in fuel.
8. It takes a lot to convert dinosaur fossils into fuel. It tends to want to return to a solid state if left to its own devices. Along the way it creates varnish, sludge, and other enemies of small passages and rubber. Modern fuels containing ethanol are even worse.
Carb disease is no joke. it will stop your vehicle without warning, and leave it needing an ambulance. Single, double, or triple filter bypass is avoidable. Open carb surgery is not where you want to be. All things considered, it is advisable to exercise your vintage vehicle regularly, and feed it healthy fuels. The occasional use of low doses of StarTron or Sea Foam won't hurt either. Ask your Carbiologist about plaque disease, and make sure your carb is healthy enough for sustained high speed activity.