Can a Bad Fuel Pump Ruin Your Spark Plugs?

by Richard Rowe
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Automobiles are complex machines, and sometimes go wrong in ways that don't seem to be related at first. Part of the art of diagnosis is understanding all the ways that the various parts on your vehicle work together, and what can happen to parts on one end when parts on the other end go bad.

Spark Plug Failure

Fuel pumps can fail in a few ways, depending on the design and what's wrong. Sometimes, they'll just die outright; but more often than not, that failure will be preceded either by consistently low fuel pressure or fluctuating pressure. When fuel pressure drops, the engine doesn't get as much fuel as it should. That causes the cylinders to go "lean" and run very hot. Spark plugs are generally designed to be the weak link in any cylinder; their ground straps will typically melt under excess heat before the aluminum pistons do. That saves the pistons and the engine, but kills the plug. So, yes: A dying fuel pump can make an engine run lean and hot, which will eventually kill the spark plugs.

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