Recognizing bad fuel pump symptoms on time can spare you a lot of trouble.
So much so that problems like being left stranded on the road or parking lot, experiencing engine malfunction, interference while driving, or else can be successfully avoided.
Taking action on time before the fuel pump completely fails is of the essence. This way you’ll save yourself from inconveniences, perhaps save some money and above all, have a safe drive.
This article will hopefully help you with that task. Besides the actual symptoms, lower in the article you can find some other useful information regarding the bad fuel pump topic.
WHY DOES THE FUEL PUMP STOP WORKING?
The main reason, in most cases, is material fatigue.
You see, the fuel pump is essentially a direct current electric motor that has an impeller inside it.
Once it gets power input, it momentarily starts to pump gas and provide a stable and high fuel pressure to the engine. This is very important as almost all modern cars have fuel injection systems which can’t work without this.
Although the fuel pump is a very robust car part built to last a long time, during its service period it rotates billions of times moving hundreds of liters of fuel from the gas tank to the engine.
Having this in mind, it’s only logical that material fatigue appears over a certain period (especially on the electric motor armature and the impeller).
It wouldn’t hurt, if you have the time, to read a more thorough explanation on Wikipedia about the fuel pump. This can perhaps help in better understanding the whole topic and the lower mentioned symptoms.
10 MOST COMMON BAD FUEL PUMP SYMPTOMS
1. The engine will occasionally not start
With one cranking the car starts without any problems and the next it won’t start at all.
One of the most common fuel pump symptoms but also the most tricky one as it can leave you stranded in a moments notice.
This symptom means that the engine is at one point getting a regular fuel supply and at the next, there is no fuel supply whatsoever.
2. The engine will not start at all
This means a lot of cranking without even the slightest sign of the engine starting.
If this symptom appears, make sure to stop cranking on time to avoid damaging the car battery and starter.
With this symptom, there is no fuel supply at all.
3. Engine will sputter at high revs
High engine revs demand maximum yield from the fuel pump. This puts the pump under a lot of stress and if it’s not in good condition the fuel supply becomes unstable.
Hence the sputtering that may be accompanied by some slight jolts while driving.
In this case, the engine can function normally at low or medium revs while only causing problems in higher revving.
4. Sudden loss of acceleration
Another one of the fuel pump symptoms that may give the driver a scare and for a good reason.
This symptom can appear at a moments notice and disappear the next.
When accelerating the engine demands a higher fuel supply and if the fuel pump is faulty, it won’t be able to pump enough fuel to the engine.
Often it can be accompanied by a sense of the car bogging down while driving.
5. Frequent long cranking before the engine starts
This is one of the bad fuel pump symptoms where the engine will start for sure but only after some long cranking.
If this symptom starts to appear regularly solve it as soon as possible to avoid damaging the starter or the car battery.
6. Higher fuel consumption than usual
A symptom like this one is best noticed when the fuel gauge needle starts falling at a rapid pace. Also, the board computer reading for the average fuel consumption will show a much higher value than usual.
When the fuel supply to the engine is limited or erratic, the engine functions in an unstable manner causing the fuel consumption to fluctuate.
Since fuel consumption is mentioned, if you’re interested in how to calculate the fuel consumption on your car, click here for a separate article on that topic.
7. The engine stalls once it reaches working temperature
Everything works OK until the engine reaches its working temperature. Then the engine starts to stall.
This bad fuel pump symptom is especially noticeable if the engine is running for a long time, like during a road trip for instance.
Just to make things clear on this part, the engine temperature has nothing to do with this symptom rather a worn out fuel pump is the problem.
A worn-out fuel pump is prone to overheating when working for a prolonged time. When it does overheat, it can start to work intermittently causing an unstable fuel supply.
This causes the engine to stall or, in more drastic cases, cut out completely.
8. Loss of engine power under load or stress
This symptom may only appear when, for instance, you tow a trailer, have more passengers in the car, have an uphill drive, or else.
The car may otherwise function normally (when driven under everyday circumstances).
More load and stress to the engine means a higher fuel demand. This will push the fuel pump to its limit and if it’s not in prime condition it will work at a lower capacity or completely malfunction.
9. Car surging
This symptom can appear as a sudden, freakish acceleration while driving. Luckily, not a drastic one in most cases.
One of the fuel pump symptoms that can surely give you discomfort and a sense of losing control over the car.
At some point, a faulty fuel pump may cause a sudden increase in fuel pressure which causes power surges.
10. Squealing or whining noise coming from the gas tank
On almost every car, once you turn the ignition key to the first position, you’ll hear a clear buzz sound coming from the back of the car, where the gas tank is located.
This is normal as once you turn the ignition key before cranking the fuel pump is activated. It has to build up pressure before you crank the engine so it can start at a moments notice.
If the buzzing sound is replaced by a squeal, whine, or even a grinding sound, then you certainly have a problem.
Before it comes to this, you may previously experience other bad fuel pump symptoms mentioned above like stalling, sputtering, or else.
If this symptom appears, check the pump as soon as possible as it is a matter of days before it fails.
If it does, the buzz sound won’t appear at all.
OTHER CAUSES THAT MIMIC BAD FUEL PUMP SYMPTOMS
These are good to know and check out before ˝accusing˝ the fuel pump for the malfunction.
Besides this on some cars replacing the fuel pump is a tedious task which involves some serious work like taking off the whole gas tank, parts of the rear suspension and so on.
The last thing you would want is to do all of that work and conclude that the fuel pump is OK.
So to avoid this take a look at these first:
Clogged fuel filter
By far the most common reason for low fuel pressure. Also, the first checking point if you have these kinds of problems.
If the filter is clogged the fuel pump can’t achieve the needed pressure and it will be constantly low.
Best first check when the fuel filter was last replaced. If it was a long time ago, replace it, just in case.
Also, if the fuel you use is of poor quality, change the filter more frequently then the manufacturer recommends.
Clogged fuel lines
The car fuel lines usually have a small diameter and a lot of bending points. This makes them prone to clogging at certain spots.
This goes double if you frequently drive with a low gas level. On every car, inevitably, a layer of debris forms on the bottom of the gas tank.
When the level is low, the pump can suck this debris into the system and overtime form a clog.
In this case, the fuel pressure will be constantly low or in more drastic cases, non-existent.
Loose clamps or connections on the fuel lines and filters
Fuel lines are a combination of metal pipes and rubber or plastic hoses. On every one of these, you’ll find a clamp or connector of some sort.
If they’re broken or not properly tightened, air gets into the system and causes pressure loss.
This means that every time you turn the engine off, fuel returns into the gas tank.
So every time the engine is started, the fuel has to be pumped all over again from the gas tank to the engine.
The result of this malfunction is long cranking and eventually starting the engine.
After starting, the engine may continue to function normally until the car is in standstill again for a longer period.
Then the fuel again returns to the gas tank and the whole ordeal is repeated.
Have in mind that fuel filter connections are also hotspots for these kinds of problems.
Loose clamps and connections will cause constant low fuel pressure and sometimes visible leaks.
Clogged filter on the fuel pump
Besides the main fuel filter, there is one more filter that can get clogged.
There are certain fuel pump layouts that combine the fuel gauge sender and fuel pump in one housing.
A common layout on a lot of cars as it’s both convenient and easily accessible for repair (you can access it from a hatch inside the passenger cabin or boot without taking off the gas tank).
In the lower part of the housing, there is usually a small filter protecting the fuel pump from debris and filth accumulated over time in the gas tank.
Because of this filth, a smudgy like substance can form on the filter causing a clog.
This will then result in constant low fuel pressure or, if very clogged, can cut the fuel supply completely.
In most cases, this filter can be successfully cleaned or replaced separately.
This filter is the next checking point if replacing the main fuel filter didn’t help.
Accident safety switch (fuel cut off switch) for the fuel supply
A lot of modern cars have this safety feature. The main purpose of this switch is to cut off the fuel supply if you have an accident (namely a car crash).
This prevents fuel spilling around and reduces the possibility of a fire.
So, if the car has been in a recent accident (even a less serious one) and you’re experiencing bad fuel pump symptoms (like you can’t start the car at all), this switch is definitely worth the check.
HOW TO PREVENT BAD FUEL PUMP SYMPTOMS?
Here are some tips on how to prevent or avoid bad fuel pump symptoms and problems altogether.
Some of the best preventive measures are:
Keep the gas tank at least quarter-full. Half-full is even better. This is the golden rule for increasing the longevity of the fuel pump. In most cases, the pump is cooled by the fuel so a low level can cause frequent overheating and lead inevitably to total malfunction.
Avoid as much as possible driving ˝on fumes˝ and completely emptying the gas tank. As mentioned, you’ll overheat the fuel pump as well as increase the probability of air getting into the fuel system.
Use high-quality fuel as much as possible and go to gas stations that have a reputation for serving this kind of fuel. Even if it does perhaps cost more in the beginning, in the long run, it’s cheaper through less maintenance.
Visit gas stations that have a good customer turnover. This means that the fuel supply is constantly renewed so you’ll always get good quality fuel and reduce the possibility of getting debris and filth in it.
Do regular maintenance on time regarding the fuel installation, mainly the filters. Regular replacement of fuel filters and checking the fuel lines will significantly prolong the fuel pump service life.
Reacting on time is a key factor.
If you experience any of these fuel pump symptoms, the most important thing to do is react immediately.
As mentioned, an unstable fuel supply can leave you stranded at a moments notice or even worse interfere with driving safety. No need to say how dangerous this can be.
Reacting on time will save other parts and systems from damage
For instance, long cranking will cause an eventual starter and battery failure. This then leads to other problems and unwanted expenses.
Diagnose the problem properly-make sure that the fuel pump is actually the problem
Similar symptoms to the ones mentioned above can be caused by other elements (for instance the ignition system). When you properly pinpoint the problem you’ll avoid a wild goose chase and throwing money away.
Think before choosing a DIY option
DIY options for solving fuel pump problems are possible but always know exactly what you’re supposed to do.
This repair involves working around flammable fuel, sometimes taking the gas tank off completely, taking off parts of the rear undercarriage in order to reach the gas tank, and so on.
If you have less experience around the car, I would limit the DIY options to perhaps changing the fuel filter or a hose perhaps. For the rest, you’ll either need more experience or professional service.
Also, if you decide to make a DIY repair, take every possible safety precaution when working around fuel. With these kinds of repairs, you can never be too careful.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com