Bad Fuel Pump — A bad fuel pump can cause a poor fuel-to-air mixture in your engine which can lead to the over use of fuel and overheating. If a fuel pump is not supplying enough fuel pressure, generally between 40 and 60 psi the engine may run lean. If the air-fuel mixture is lean, there is an excessive amount of air and not enough fuel to go with it causing additional heat during the combustion. The limit of this can cause the engine to overheat because it goes out of its thermal operating area. Research indicates running even slightly lean— by as little as 5-10%— can increase engine temperature significantly, particularly when under load or high-speed conditions.
Lean conditions are when there is not enough fuel in the air–fuel mixture due to either insufficient fuel flow, too little time for the injector to inject the needed fuel into the cylinder, or another issue meaning that not all of this carbon can enter a standard combustion process. This creates difficulty in managing the heat made during combustion and will all but guarantee something like pistons eventually enlarge beyond their specified tolerance levels (usually resulting from melting), burn your valves, or destroy your head gasket (*See ‘EXTRA INFO’ below). Sustained overheating as ***product of an inadequate fuel supply over *** however can result in costly repairs., which essentially is a by-product of not getting enough fuel into the engine will slowly toast your engine (at this stage replacement valve guides will be the least of your worries), but at times hell hath no fury etc., etc. and when you are groping for resources additional spare cash is often less available than it needs to be). Fuel Delivery Issues (20% of the Cases)The fuel pump is one of the most common things that cause issues, and many automotive technicians claim that it could lead to up to 20 per cent of all overheating cases.
In other words, fuel pumps are actually cooled by the gasoline they pump. It is located directly on the frame of your vehicle and sometimes when a fuel pump wears out due to aging or has to work really hard because it is beginning to fail, it can cause itself to become too hot. If a faulty code shifts the computer into lean fuel mode, a hot fuel pump can worsen the problem by delivering less fuel, making the lean mixture even worse. Worst of all, a fuel pump on the decline will induce engine misfires — thus even extra heat inside the combustion chambers. Keeping your fuel tank full — or close to it, say the fuel system experts — is wise, as the risk of pump-roasting due to repeated cavitation events jumps up to 30 percent with low fuel levels, especially on long drives in hot weather.
In other scenarios, such as in 2020, Toyota pulled more than thousands of vehicles off the road because of a fuel pump recall which was causing them to stall and overheat. If they not working properly, it will be disastrous for engine health as shown by the large scale incidents.
As Enzo Ferrari said once: «Aerodynamics are for people who cannot build engines» and he also said the truth in opposite direction «The engine is the heart of car, but the fuel is its blood to keep it alive. This quote emphasizes the importance of uninterrupted fuel delivery to achieve best engine performance. As the fuel pump malfunctions, it can starve the engine of this lifeblood, starving it and causing an opt overheat by scourgingv up the adequate balance in the Air/Fuel mixture.
Go to Fuel Pump if you would like to read more on fuel pump problems and how do diagnosing it.