How to Make Fuel Pump Work Again
Today is not the solar day nosotros volition see hybrids and electrical cars replace fuel-injection vehicles for adept. Maybe soon simply not withal. Until then, we all the same have to work on cars who rely on a good
As an car mechanic, you'll have to work on cars with a "crank/no start" status, which could eventually exist acquired by a faulty fuel pump. Just as with everything within the auto mechanic world, it's not necessary that simple. A faulty fuel pump can cause a variety of different mistake symptoms and tin sometimes be a piddling tricky to audit and diagnose correctly.
To help y'all with that, this article will explain how most mutual automotive fuel pumps work, highlight some of the different pump types, as well every bit to pinpoint some of the most common bug and how to fix them.
But, offset things outset!
What is a Fuel Pump?
There's a lot of dissimilar types of automotive fuel pumps simply they all have one thing in common. Their purpose is to feed the engine with fuel by pumping gas from the tank, causing a positive force per unit area in the fuel line to push the fuel all the way up to the injectors. Near fuel pumps are controlled by a relay, which is also controlled by the
Unlike Types of Fuel Pumps
Almost any internal combustion engine gets its fuel from a fuel pump of some kind merely we'll stay focused on automotive fuel pump here.
The primary type of fuel pumps are:
- Mechanical pumps
- Electrical pumps
- Directly-injection (GDI) loftier-pressure pumps
Mechanical pumps
Mechanical pumps were by and large establish in old carburetors engines. I've been a mechanic for over 10 years now and I've never had to piece of work on a mechanical pump on a customer's car. It may not be super useful noesis for today'southward technicians but knowledge is never wasted. With the arrival of direct-injection though, mechanically-driven pumps
According to Wikipedia, "mechanical pumps are a type of positive displacement pump that
Not sure you lot got information technology right? Take a wait at this cool animation!
Mechanical pumps are usually installed on the side of the engine and the piston creating the pressure level is either directly in contact with the camshaft or via a connecting rod. This type of pump was widely spread earlier 1985 just they weren't simply as efficient as newer electrical models. Merely ask an onetime mechanic about how heat could easily vaporize the fuel in the lines, causing fuel starvation and ultimately engine stalls.
Anyway, you won't see those pretty oft unless you work on one-time musculus cars or marine engines.
Electric pumps
In today'due south cars, fuel pumps are electric and are located in the fuel tank. The new design involves less moving parts than a mechanical pump requiring less maintenance than ever. The in-tank system besides helps in cooling the pump and the fuel preventing any take chances of vaporization in the lines.
Another one of the advantages of having the pump in the fuel tank is the added rubber. It may seem counter-intuitive since electricity produces sparks and sparks and fuel don't mix well, but liquid fuel is actually non-flammable making information technology a lot safer than having it almost the engine where fuel leaks could easily grab on fire.
Electrical pumps are also more efficient because of the lack of resistance caused by moving mechanical components. And with the price of fuel these days, everything making your car more efficient is a no-brainer!
Direct-injection (GDI) high-pressure pumps
In the last couple of years, nosotros also had the pleasure to meet directly-injection being installed on nigh every car coming out of an assembly line. I say "pleasure" because direct-injection is a lot more efficient than any other fuel organization fabricated to date.
Straight-injection pumps are usually mounted somewhere close to the engine and connected by a metal hose to a track supplying each cylinder with its ain fuel. GDI fuel injection systems use no injectors and directly feed the engine with highly-pressurized gasoline (upwards to 2,500psi!), injecting it directly in the combustion sleeping accommodation instead of the intake manifold. This allows the European monetary system (engine management system) to continually conform the air/fuel ratio in real-time, resulting in lower fuel consumption while producing a college ability output.
No demand to say that conventional fuel-injection systems weren't doing a really expert task in adjusting the air/fuel ratio, relying on a technique we could summarize as shooting the aforementioned amount of fuel in all iv cylinders at one time, regardless of the efficiency, and monitor the O2 sensors after to see
Clearly not the best…
Information technology's important to know that on GDI systems, the high pressure level of the fuel is created by the high-pressure pump located under the hood, but the job of bringing the fuel from the tank to the high-pressure pump is nonetheless taken care of by a regular electric pump located inside the tank. Stay aware of that when working on a GDI vehicle as not to be mistaken about which pump is in trouble and which 1 you lot demand to inspect first.
Possible Fuel Pump Bug
All the different types of fuel pump accept unlike components and will have different symptoms and unlike issues. Let's only forget about mechanical pumps for now, since it's unlikely you'll have to work on one in the future.
Anyhow, here are the nearly common problems for the 2 main fuel pump types, the almost common bad fuel pump symptoms, how to correctly place the problem and how to fix information technology.
Electric Fuel Pump Problems
Electrical bug
It makes sense that, in an electric pump, the most common problem is an electric ane. A loftier number of electrical components implies a high number of connections, multiplying the risk of an electrical circuit malfunction.
- What are the symptoms?
No matter what is causing the electric trouble, the fuse, the wiring, etc., the symptoms will all be much the same. When no power reaches the fuel pump it simply stops working. The engine will fire what'due south left of fuel in the fuel lines and it will stall. The trouble can be intermittent and the engine will wiggle, stall, start again, jerk some more, and so on.
- How to prepare it
If yous went to auto mechanic merchandise school, you learned how to follow a standard procedure to identify an electrical problem. If you don't, let me demonstrate it quickly:
- Confirm the problem
- Examination for ability at the malfunctioning component
- Check the ability source, fuse, and relay
- Inspect the wiring
- Change the ECM
Kickoff, brand certain the problem is present. Yous can't find a trouble if information technology's not nowadays. Elementary every bit that!
Normally, as for a ability window regulator or a
If everything is skilful up to at present, you need to become to the connector of the fuel pump and examination it for power and ground. If there are current and footing in the connector, and the connector pins seem alright, you probably got yourself a faulty fuel pump. You can always test for an open excursion in the pump. If the circuit is open inside the fuel pump, in that location's no need for further testing, you need a new pump. If the internal circuit of the pump is ok, something mechanical may all the same be broken inside. It doesn't matter what component is broken within because, unless you lot want to rebuild the fuel pump, you'll have to supervene upon the fuel pump assembly.
If you don't have ability to the fuel pump connector, yous are allowed to cry a niggling before starting to strip the motorcar's interior. You've got an electrical brusque or open circuit somewhere and yous'll have to follow the wires, testing for ability and ground until you lot find that faulty wire or connector.
At the stop of every troubleshooting nautical chart ever fabricated, there's always the accented final resort pick. If you checked everything and everything is absolutely perfect, they ever advise you lot replace the ECM, but that'southward very unlikely… If all seems good on the electric side, it could be something else. I suggest you try to eliminate other common bug on this list before trying to replace your ECM!
Worth mentioning, if you lot have an OBD2 scan tool, you can always try to read the DTCs earlier doing anything else. Some newer automobile tin tape a code when the fuel pump is not working correctly , giving you a adept thought of where to go next…
Mechanical issues
Even though this pump is electric, the pump action is actually created by moving mechanical parts and everything in motility is decumbent to article of clothing and chafe. Various parts tin become loose or seize together preventing the fuel pump to piece of work correctly.
- What are the symptoms?
In instance something goes berserk in the fuel pump and either seize or go loose, the fuel pump will probably cease working. In this case, the symptoms volition be almost exactly the same as for the electric problem. The engine will jerk and stall. Because mechanical wear is progressive, the owner of the car may come across it coming, compared to the electrical problem which will happen suddenly.
The car can brainstorm to feel like it's losing ability when driving uphill. Fuel consumption can too go up for no apparent reason. Slight jerking tin also be felt when pressing on the accelerator pedal later on a stop. Cold start in the morn could also become a trouble and the engine may take a little more cranking to starting time.
- How to fix it
There no easy way to really place a mechanical trouble, other than checking the fuel pressure with a fuel pressure level approximate. Unfortunately, most cars don't come with a fuel pressure inspection port anymore (information technology was pretty common with cars made in the 60s-70s). If the motorcar is non equipped with 1, you'll need to open up the fuel system at one of the line's connexion and insert your fuel gauge before reinstalling everything to start the engine and become a psi reading.
If the pressure level is also low or as well high, brand sure at that place'due south no impairment to the fuel line, somewhere under the automobile, that could limit the menstruum of gasoline.
If everything
Clogged strainer
On the intake port of the fuel pump, at that place's a little strainer acting as a fuel filter. Rust and dirt independent in the tank can clog the strainer and prevent fuel from correctly entering the fuel pump.
- What are the symptoms?
This kind of problem could pb to an uneven delivery of the fuel to the injectors causing engine jerks or sputters. Sputtering may merely occur for a few minutes at a time earlier returning back to normal, nonetheless, be sure that it won't set itself and may aggravate later.
Based on my own feel though, this is not a really common trouble. Gasoline, these days, is cleaner than ever and finding dirt in a tank is unusual. This is a problem happening mostly with older and rusty cars.
- How to fix it
Inspect the tank and the strainer. If information technology'southward full of rust, you could have found the trouble. Unfortunately, yous'll accept to remove the fuel pump to confirm the strainer is clogged and this volition require the rear seat removal at all-time (some cars have an access port to the pump nether the back seat), the fuel tank complete removal at worst.
If the strainer is chock-full, you could clean the strainer using a portable vacuum and remove all the pocket-sized metal $.25 by mitt. You could also buy a new strainer at nearly auto part stores and replace information technology if your budget is tight. Personally, taking into account that you take already removed the fuel tank or back, removed the fuel pump to inspect information technology, most of the job is already done. I would probably supersede the whole pump assembly anyway unless your fuel pump has already been replaced in the terminal 6 calendar month.
And information technology also depends on the cost of the fuel pump. Most aftermarket pumps are pretty cheap but y'all never know. Sometimes, some parts
Merely if yous can afford it, just replace the whole affair…
In the case of a vehicle with a "crank/no start" status, the first thing to exercise is to heed near the fuel tank if you lot can hear a slight buzzing dissonance when the key is turned to the on position. If not, the fuel pump may well be seized. A trick-of-the-trade here is to utilize a soft-face hammer to hit under the tank. The fuel pump may well start to work again. Once information technology's started, I wouldn't cease the engine until the motorcar is parked somewhere you lot tin can work and set that out though!
Whining racket coming from the fuel pump
When the central is in the ON or RUN position, information technology is admittedly normal to hear a slight buzzing noise coming from the fuel pump. It's non a common problem but, sometimes, the fuel pump could first to make a loud whining dissonance. This is unremarkably a sign that the fuel pump is almost at the end of its life.
- How to fix it
The first matter to attempt when your motorcar starts to brand a loud whining dissonance coming from the rear is to fill the gas tank completely. A low fuel level requires the pump to work harder to build a good fuel pressure level in the arrangement and it could why it's whining, especially if the pump is old.
If the dissonance stops afterwards refilling the tank, that's a sign that the fuel pump will need to be replaced soon. It however works simply information technology's going to fail at some signal and the car gamble to stall somewhere.
If the noise doesn't stop subsequently new gas is put in the machine, in that location's no other solution than to replace the pump.
whining racket, hard starting, engine functioning issues, and an inability to start the car.
Directly-Injection (GDI) High-Force per unit area Pumps
Mechanical Problems
Proper maintenance is admittedly crucial with GDI systems. As opposed to an electrical fuel pump, which is running within a fuel tank with near no lubricant at all, the GDI pump is lubricated by the engine oil. A lot like the mechanical fuel pump, the high-pressure level pump is as well driven mechanically. Premature wear tin can occur quickly on various components in contact, such every bit the cam lobe and the follower, if oil service is not performed as oft equally required by the manufacturer or if a dissimilar oil viscosity is used.
GDI fuel pump
- What are the symptoms?
Typically, when a mechanical failure occurs on a GDI pump, the pressure in the system will decrease and the high-pressure won't be that high anymore. Usually, the vehicle will put itself on "LIMP" manner and volition virtually of the fourth dimension betoken LIMP (or something similar depending on the manufacturer) on the dashboard. The LIMP mode is a safety procedure that volition profoundly reduce the speed the automobile can go in order to forestall the driver from dissentious the engine fifty-fifty more.
- How to fix information technology
First, scan the auto and read the DTCs. About of the fourth dimension, a code is recorded whenever the vehicle enters LIMP mode. This will give you lot a good idea of the faulty component.
If for some reason no code is recorded, make certain the problem doesn't come up from the conventional fuel pump in the tank. If the electric fuel pump is not working and it is not feeding fuel like it's supposed to, the GDI pump won't be able to do its job either.
Once y'all made sure the in-tank pump is working, you'll have to exam the fuel pressure coming out of the high-force per unit area pump, a lot like you would practise the fuel pressure on a regular fuel organization. If the pressure is not according to specifications, a new GDI pump is needed.
Warning
Always brand certain to follow all high-force per unit area fuel organization depressurization procedures before servicing. Ane good technique to depressurize the fuel organization is to remove the fuel pump relay and go along the engine running until it stalls. Even so, always confirm the organization is empty earlier disassembling and e'er follow the manufacturer's recommendations.
Pressure and temperature sensors
Bad sensors tin often lead to misdiagnosis of faulty GDI pump when it's actually a faulty sensor trouble. The pump relies on high and low-pressure sensors, as well as, temperature sensors to evaluate the corporeality of fuel needed and the exact timing and duration of the injection. If a sensor is misreading whatsoever value, the pump won't be able to piece of work correctly and the vehicle could enter LIMP mode.
- What are the symptoms?
Depending on the faulty sensor and the extent of the failure, symptoms could go from jerking to complete stall. Near of the time, the vehicle will enter LIMP mode and the check engine light will light up.
- How to ready information technology
To find out which sensor is causing the problem, you lot'll need to plug in a skillful OBD2 scan tool to check the live data of the vehicle and the vehicle's repair transmission with all the sensors specification to compare the results. Unremarkably, the faulty sensor will evidence a reading out of the recommended threshold. Replace the sensor, erase the lawmaking and confirm everything is back to normal.
Fuel Leaks
An internal or external fuel pump leak will cause the fuel pressure to decrease, also leading to jerking and stalling. Reduced pressure can also lead to overheating which could damage the pump and the whole fuel system even more.
- What are the symptoms?
When a small leak is present, the fuel system will virtually likely depressurize when the engine is turned off. This will crusade longer cranking fourth dimension to burn down up the engine. Overheating of the pump is also to exist expected whenever the motorcar runs on reduced fuel pressure. Overheating will reduce the lubricant holding of engine oil and will cause a metal to metallic contact. If the cam lobe and the follower run dry for an extended period of fourth dimension, permanent damage to the cam lobe could occur and the camshaft will have to be replaced equally well every bit the GDI fuel pump.
GDI fuel pump follower
- How to prepare it
To notice a leak in a high-pressure fuel system, you'll demand to perform an injector residue and a
Software Issues
Finally, if everything else fails, take some time to make sure the ECM software'due south version is up to appointment with the latest update bachelor because everything is ultimately controlled past the ECM. Manufacturers won't necessarily call every car possessor to get the latest version installed every time a new update is released. This will also require an OEM scan tool or a visit to the dealership for a quick reflash.
Last Words
Fuel systems are circuitous systems and they tend to go a little more complex every twelvemonth. But, GDI systems are paving the way for a brighter hereafter and open new possibilities, from cylinder deactivation on-need to college compression ratios and meliorate fuel mixture monitoring thanks to the new wideband O2 sensors.
The time to come is vivid indeed but you'll need to stay on elevation of your fuel injection game if y'all want to perform as an auto mechanic in an manufacture on the verge of a technical revolution!
Source: https://www.themechanicdoctor.com/fuel-pumps-problems-how-fix-them/
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