Ehhh, Yes…it is indeed plausible if the fuel pump sucks! Detonation, or “knocking” and “pinging,” is premature or uneven combustion of the air/fuel mixture in the combustion chamber producing pressure and heat. Detonation is one of the factors that can be caused by a lean air-fuel mixture, and this leads to consider how a failed fuel pump (which may be unable to provide enough fuel) translates into detonation (and more).
Modern engines usually need a certain air-fuel (14.7:1 is the most common) for efficient combustion. When the fuel pump fails, it may fail to deliver enough fuel and cause a lean burn found as a result of too much air in the combustion cycle compared to the amount of fuel / oxygen that has been displaced. The lean condition also raises combustion temps, which in turn means an increased likelihood of detonation. Bosch's engineers say that operating an engine on a lean mixture will send cylinder temperatures soaring as much as 200°F, making the potential for knocking nothing short of phenomenal.
Inconsistent fuel pressure may be another sign of a failing fuel pump. In order to meet the fuel requirements of most vehicles, that fuel has to be delivered at a constant pressure level (usually somewhere in between 40-60 psi), depending on the engine. If the fuel pump is unable to hold this pressure, it can cause the delivery of fuel to fluctuate which results in uneven burning and detonation. Thousands of vehicles were recalled by General Motors in 2019 due to a problem with low fuel pressure caused by faulty fuel pumps leading to engine knocking and performance problems.
The fuel pump relay or electrical connections can also cause detonation and not only pressure problems. This means that a bad relay can clip the fuel pump on and off in short intervals where the engine is not getting enough fuel. Volkswagen saw a similar situation in 2020 with a recall due to fuel pump relay issues causing reduced fuel delivery rates and higher engine knock occurrence.
Detonation can not only hurt engine performance but cause serious long-term problems. According to the AAA, constant detonation can result in piston damage…along with cracked cylinder heads and even complete engine failure. To fix detonation damage usually costs between $1,000 and $3,000 depending on how severe the damage is and which parts need to be replaced.
Detonation is a result due to inadequate Fuel systems upkeep. The fuel filter lasts only 20,000 to 40,000 miles; replacing it periodically prevents debris from clogging the fuel lines or pump. A clogged filter, on the other hand, obliges the pump to work harder consuming more fuel and making it more prone to starvation which in turn results in the possibility of a lean mixture and consequent detonation.
As mechanical maestro Scottie Kilmer would have it, 'the fuel system is the heart of a car. Proper maintenance — for example by checking and maintaining fuel pump performance or good fuel pressure — can go a long way towards reducing the potential for detonation and keeping your engine happy in the long run.
Visit Fuel Pump for information on how fuel pump affects engine performance and maintenance tips.