and unless the pump (or pressure regulator) fails in such a way to deliver less fuel that the engine runs lean.... but then you have the DME which will adjust the fueling -- extend the injector active times -- to compensate.
You would also likely see the CEL on (flashing on too) from "rich" misfires which put the converters are risk of damage from overheating from the raw gas being fed them.
In modern cars about the only time you'll see a 'fouled' plug is if an injector is leaking, or if the engine is being too richly fueled due to a temp sensor failure that reports the temp less than it really is.
Otherwise these modern fuel injected engines are very precisely fueled.
That is the function of the DME and is done so in order to protect and satisfy the very stringent exhaust gas composition required by the converters so they can do their jobs right and the emissions are kept at acceptable levels.
Prior to modern engine control systems 'fouling' generally arose from the lousy state of tune car engines had or a fault with the carb float. Even then the plugs didn't foul. For instance my early Datsun 510 was running rich traced to a fuel line coming apart and pieces jamming the float so excess fuel was in the float bowl. The engine did not misfire, or act like it had fouled plugs. It emitted visible dark exhaust smog and had lousy fuel mileage. This was back during the 1st gas crisis and it was my paying attention to the fuel mileage that really clued me in something was amiss. Another insidious failure mode was the float would develop a crack in its outer layer which would allow fuel to soak into the float and of course it would get heavier and allow the fuel level in the float bowl to rise with the result the engine would be running rich.
More often, many an owner fouled plugs by pumping the gas pedal too much and causing the accelerator pump to flood the engine and foul the plugs. This is where holding down the gas pedal to open the throttle wide and cranking the engine to let the plugs dry out came from.
People do not realize how serious this precise fueling is. There is the initial emissions compliance the car must have, not to mention being able to come somewhere near the EPA says the fuel economy should be for a particular vehicle. There is the new car warranty time during which the engine must run right. Then for some emissions related components there is the federal emissions hardware warranty laws which require the factory to replace any failing components at its expense. The big ones are the converters.
Then the EPA constantly -- through contractors -- brings in every day passenger vehicles for emissions compliance testing. If the EPA started to notice a too large a number of a particular make/model of car failing to remain there would likely be serious repercussions to the automaker responsible.