Once it’s been determined that the fuel pump is the issue the next logical question is how to fix a fuel pump problem?
This is one of the more serious car problems as it severely influences the engine function as well as interfere with driving. Namely because the engine will sputter, surge, stall or cut out altogether.
This article will hopefully help solve this problem or at least give some good guidelines.
If you want to find out what are the most common causes and symptoms of a fuel pump problem then read these articles:
10 COMMON BAD FUEL PUMP SYMPTOMS ON A CAR
FUEL PUMP PROBLEM-8 MOST COMMON CAUSES
WHAT TOOLS AND PARTS WILL YOU NEED TO FIX A FUEL PUMP PROBLEM?
In the majority of cases you’ll need:
Basic set of tools
Basic set of screwdrivers (mostly medium-sized flathead and Philips)
Pair of combined pliers
Protective clothing and gear (thinner working gloves, protective glasses, protective overalls). These are needed especially if the fuel pump is located on the underside of the car
Carjack and a pair of jack stands. This is only when the fuel pump is located under the car. Otherwise, if you can reach it through the access hatch from the passenger cabin or boot, you won’t need it
Some old cloth or paper towel to wipe spilling fuel.
A multimeter or tester
It would also be good to have some isolation tape at hand and a scalpel.
You might need all or just some of these tools.
Regarding parts, I would advise you to wait until the actual problem is found. This is tricky as sometimes you’ll have to pick apart the car meaning you won’t be able to drive it to get parts.
But better ask someone for a drive then throw away money on unneeded car parts. Besides this, if the problem is more simple (like a fuse, faulty clamp, broken hose, or else) there is a good chance you can fix the problem with what you already have around the household.
HOW TO DETERMINE IF THE FUEL PUMP IS THE PROBLEM?
Before starting any kind of repair it would be good to determine if the fuel pump or parts of the fuel system is the actual problem.
Some of the symptoms of a bad fuel pump are similar to malfunctions caused by other systems.
The mentioned sputter, surge, or stalling of the engine can for instance be caused by a fault in the ignition system (like spark plugs, ignition coils, or else).
In order to be certain the best way is to check the fuel pressure.
If the fuel pump is faulty, the pressure will either be weak or non-existent.
Also if there is a clog of some sort in the fuel lines (like a clogged filter) this will also be noticed. The fuel pressure will gradually build up instead of instantaneously.
This is best done by using a fuel pressure gauge. It will immediately give you a good picture of what may be wrong.
Weak fuel pressure can mean a worn-out fuel pump, clogged filter, clogged fuel line, or else.
If there’s no pressure at all this can mean, for instance, that there’s no electric power supply to the pump or that the pump has failed completely.
Whatever the case, all of this will give you a good lead on what to do next.
On some cars, you’ll find a connection terminal somewhere on the fuel line intended for connecting the fuel pressure gauge. It will usually have a Schrader valve on it for easier access.
On others, you’ll just have to find a convenient place (like parts of the fuel line near the engine where there are rubber hoses with clamps). In this case, they have to be taken off and connected to the gauge.
For electric faults, you can use a tester or multimeter. Of course, you can use an OBD tool and see if there’s a fault code.
The main point here is to determine that the fuel pump is the actual problem, not anything around it.
In some cases, you’ll have to take off the fuel tank in order to reach the fuel pump and this is a serious and lengthy job. It may even involve taking off parts of the rear undercarriage in order to take the gas tank off.
The last thing you want is to do all of this work and conclude that the fuel pump is not the problem.
If you decide to go down the DIY lane:
Have in mind that you’re going to work around highly flammable fuel. Since there will be minor fuel spills or you’re going to be accessing the fuel tank make all the safety precautions needed, mainly avoid any kind of open flame, sparks, or else. Make sure to secure your working area properly.
It would be good to do this job, if possible when the gas level is at minimum, best just after the gas tank warning light comes on. This goes double if you have to take off the gas tank. Less spilling and less danger this way.
Best take off the minus terminal on the car battery. This way you’re 100 percent sure that there’s no power supply to the fuel pump. Some people just turn off the ignition or pull the fuse out which is essentially also OK. But this way you may forget to turn off the ignition for instance and cause an accidental electrical spark near the gas tank. No need to say what kind of danger this is.
Wear protective gloves. If the fuel pump is located on the underside of the car, some protective glasses and overalls will also come in handy.
If you have to raise the car (which you will if the pump is located on the underside or if you have to take off the gas tank) make sure to secure it properly. Use jack stands, wheel chocks, or any means available that will ensure 100% safety. Otherwise, you’re at risk of the car falling on you while working.
Use only hand tools. The force of power tools will not be needed in most cases. They can cause parks and this is very dangerous around gas tanks or fuel leaks.
HOW TO FIX A FUEL PUMP PROBLEM?
In a previous article, it’s been stated what are the most common causes of a fuel problem.
If you want to read that article click here.
The possible solutions will be stated in the similar order:
1. REPLACE THE FUEL PUMP
If you’ve concluded that the fuel pump is the problem then there is only one probable outcome: complete replacement.
Most of the fuel pumps are made for one-term use. The housing of the pump is crimped making it hard to open without damaging it. Even if you succeed, returning everything back into place and making it function is not likely.
Perhaps most important: if you were to somehow repair the pump, how wise is it to put it in contact with a full tank of gas? Any kind of spark means disaster.
So best by a new one and call it a day. Be sure to buy originals or quality replacement parts, cheaper parts may mean another replacement in the near future, not to mention that it can cause engine problems if it fails.
Regarding the replacement procedure, you’ll encounter two types of fuel pumps:
These pumps are located outside the gas tank, usually near the tank or somewhere down the fuel line
Fuel pumps in the gas tank
Fuel pumps like these are mounted in the gas tank and are essentially a part of the tank. They are also, in most cases, combined with the fuel gauge sender in one plastic housing.
The replacement procedure is not that complicated but it highly depends on the car model you drive.
On some it’s pretty easy, on some it can be a tedious task that demands taking off the gas tank.
So, if you want to learn how to fix a fuel pump problem by changing the fuel pump, some previous knowledge around car repairs would be good.
2. CHECK OR FIX THE ELECTRIC CONNECTIONS
The lack of electric input may show the same symptoms as a malfunctioned fuel pump.
So if the pump isn’t working at all (like there’s no buzz sound coming from the gas tank), check the electric input and connections first. This will perhaps save you from unnecessary work and cost.
The best way is using either a tester or multimeter.
When you have these at hand then:
Gain access to the fuel pump or fuel pump housing. If it’s externally mounted then go under the car and find it. If you have an access hatch under the rear passenger seats or in the boot, find the hatch and take off the lid (this is the procedure on most cars).
Take off the wire connector(s). Then use the tester or multimeter. Put the clamp of the tester or the multimeter probe on a clean part of the car body for a good ground connection
Go through the pins (or another kind of connection) and see if there’s either a glowing lamp on the tester or a near 12 volt reading on the multimeter (for 24 volts will be of course near 24 volts).
If there is, the electric supply is OK which means the fuel pump motor is the problem.
If there’s no electric input, then don’t bother taking out the fuel pump until you solve this issue.
So, this part is a turning point if you want to know how to fix a fuel pump problem.
If the electric input is OK, start planning to take out the fuel pump.
If there’s no electric input, the fuel pump may not be the problem.
Other things you should check regarding electric connections are :
Wiring harness connectors
These get rusty or loose over time, especially if they’re located in a place where there’s moisture or if the wiring is strained.
On most car wiring installations, you’ll find one of these connectors by following the harness from the fuel pump.
If there is rust, use some contact or WD-40 spray to solve the problem.
With loose contacts, either try to tighten them or replace the connector altogether.
Points where the installation is bent or squeezed
Most likely places are tight spots through which the installation is mounted and bending points.
Broken wires and damaged insulation can cause loss of power input as well as a short circuit.
A pretty rare problem, but if everything else is OK, then definitely worth the check.
Repairing this is easy: just connect the old wires, best solder them and insulate with tape. If needed, extend the wire so the problem doesn’t appear again.
Bigger problem is finding the broken wire and its exact location.
In most cases, a very tedious job since the wire is usually a part of a bigger harness. Even worse, the broken wire cannot sometimes be seen as the outer insulation is intact while the copper wiring inside is broken.
3. CHECK OR REPLACE THE FUEL PUMP FUSE
When talking about how to fix a fuel pump problem, replacing the fuse is definitely the easiest fix.
This is also the first place to check if there’s no electric input to the pump.
First, find the exact fuse for the fuel pump using your car manual, Google it or use YouTube.
Check the fuse using a car tester, multimeter, or by visual inspection.
If you’re not sure how to change a car fuse, click here for a separate article on that topic that will explain the whole procedure in detail.
There is also a video tutorial that you can watch our YouTube channel.
4. CHECK OR REPLACE THE FUEL PUMP RELAY
When the fuse is OK and there’s still no electric input to the fuel pump, the next checkpoint is the fuel pump relay.
One more simple thing you can do if you want to learn how to fix a fuel pump problem.
First, find the relay. It’s usually located in the fusebox or on a separate connection rail with other relays.
If you’re not sure about your car model, best check the manual, Google it or use YouTube. Sometimes the location may be unaccessible or hidden making it pretty hard to find.
In order to make sure the relay is causing a fuel pump problem:
Listen for a clicking sound when you turn the ignition to the position before cranking.
Once you’ve found the relay turn the ignition key and listen. If it works properly you’ll hear a slight clicking sound.
No clicking sound can mean either the relay is faulty or there may be no power supply to it.
To make sure the electric input is OK, use a tester or multimeter. Pull out the fuel pump relay and check the contacts in the fuse box housing or connection rail.
Also, check that the contacts are clean and firm. Over time, due to heating up, a grime can build up or the contacts can get loose. These can both cause a loss of conductivity.
Override the relay
This method is a bit more rudimentary but very effective in concluding that the relay is the problem.
Take out the relay, use a piece of isolated wire, and cross-connect the relay power input and the lead that goes to the fuel pump (override the relay). If you hear the fuel pump buzzing, then it’s certain that the relay is faulty.
Make sure not to make a short circuit. Also, don’t hold the wire connected to long, just a few short touches will be OK.
Take out the fuel pump relay and test it
Use two pieces of wires and connect to a 12-volt power supply (like the car battery) and use a multimeter.
Once connected, if everything is OK, the relay should click and the multimeter should show that it conducts electricity. This test will both show if the relay actually works and if it conducts electricity properly.
Have in mind that sometimes the relay may click but not conduct electricity. This is because the relay mechanism works but the main contacts are burnt out or faulty.
So, if the relay is faulty, then replacing it is next.
This is a simple procedure. Just pull out the old and insert the new one. Simple as that.
Make sure that the new relay is the same type and that it has the same connections as the old one.
If the relay contacts in the fuse box or connection rail are filthy, use some contact spray and clean them. When they are loose, try tightening them with pliers or with a flathead screwdriver.
5. CLEAN OR REPLACE THE PRE-FILTER ON THE FUEL PUMP
When talking about how to fix a fuel pump problem, there is one that is frequently overseen.
Besides the main fuel filter located on the fuel line, there is on more filter located on the fuel pump housing.
This problem is typical for fuel pumps combined with the fuel gauge sender in one plastic housing.
The mentioned filter is a sock-like filter located at the bottom of the housing.
It’s in charge of stopping debris from the gas tank getting into the fuel pump and damaging it. First line of defense so to say.
If this filter is causing problems and you have to replace it then:
Disconnect the wiring and fuel lines and take out the fuel pump housing.
Take off the old filter; it will usually be held in place by a plastic clip (or a small screw maybe)
Take off the old filter, be careful not to break the plastic clip.
Clip-on the new filter. There is also the option of cleaning the old one.
Return the fuel pump housing into place and reconnect the wiring and fuel lines.
All in all, not a complicated job but involves taking out the fuel pump housing.
This is why it’s always best to change this filter while making other repairs around the fuel pump (like replacing it or fixing the fuel gauge sender for instance).
The best solution is buying a new pre-filter, if that’s not possible then best clean the old one with, for instance, compressed air.
6. REPLACE OR FIX THE FUEL LINE CONNECTIONS
Most common issues regarding fuel lines are:
Cracked or damaged fuel lines
Fuel lines are a combination of small diameter metal or plastic pipes and reinforced rubber hoses.
The hoses are usually the weak spot, especially places where they’re bent.
The best remedy here is to replace the hose completely if it’s damaged.
In case the rubber hose is faulty:
Find the connection points of the faulty hose.
Loosen the connections on both sides(like clamps, clip-on connectors or else)
Loosen any additional holders or clamps holding the hose in place
Remove the faulty hose completely.
Install a new one and tighten properly.
Tighten any additional holders or clamps
Check for leaks
If the metal or plastic pipes are damaged the principle is basically the same. The main difference is that these pipes are more rigid than rubber hoses so removing and installing is a bit more complicated.
Also, they are fixed to the car underside so dismantling other parts of the undercarriage may be involved.
The most common cause of trouble is faulty clamps or fuel line connector clips.
Replacing a faulty clamp is an easy procedure while replacing a fuel line connector slip may be somewhat more complicated.
These tend to be heat pressed on to the hose by the manufacturer so sometimes you have to change the whole hose in order to avoid leaks.
The clip can be bought and replaced separately, the only obstacle may be fitting the hose on properly.
Some other hotspots for these problems are bending points and the connections between the solid pipes (metal or plastic) and the rubber hoses.
7. REPLACE THE FUEL PUMP SEAL
This gasket is present with fuel pumps that are combined with the fuel gauge sender.
The gasket is made out of thick rubber and is pretty resilient. One of the more rare problems when mentioning how to fix a fuel pump problem.
Mostly happens due to physical damage.
If this happens, you may get a check engine light as air gets into the gas tank and causes problems with the air-fuel mixture.
Also, a smell of fuel may appear inside the passenger cabin.
When this gasket is the problem you should:
Disconnect the wiring and fuel lines and take out the fuel pump housing. The gasket is located at the top of it.
In most cases, the gasket is removed by sliding it towards the lower part of the fuel pump housing. When doing this, be careful not to damage the float of the fuel gauge sender.
Put on a new gasket, this way in reverse. First, pull it over the lower part of the housing then towards the top
Return the fuel pump housing into place and reconnect the wiring and fuel lines.
Just like with the pre-filter, this is a simple repair. The downside is that you have to take off the whole fuel pump housing.
If doing any kind of other repairs around the fuel pump, best inspect the gasket right away in order to avoid this problem altogether.
8. REPLACE OR FIX THE ECU UNIT
Well, this is the most costly repair regarding the matter of how to fix a fuel pump problem.
Luckily it rarely happens.
It’s worth the check if all other methods for fixing the electric supply to the fuel pump fail.
Replacing the car’s ECU unit is not in the usual DIY realm so I wouldn’ recommend it unless there are proper tools, software, and above all, expertise.
The replacement procedure is not that complicated but making all the settings, resets, fine-tuning, and else is where the expertise kicks in.
Also, having the right tools and computer software is essential to finish the job.
So, I would avoid a DIY option unless you have all of the above mentioned, especially the expertise.
The obvious option is buying a new ECU unit which is pretty expensive.
Then you have the option of a used one which is pretty risky unless it’s from a known source. Better option then a used one is trying to fix your own ECU.
There are specialized workshops that do this very professionally and in quality, so definitely worth the try.
In most cases, if you have at least some experience around fixing cars, you’ll know how to fix a fuel pump problem.
Again, take all of the safety precautions needed. Never underestimate working with flammable fuel. One moment of negligence can mean a lot of trouble.
Also, make a good assessment of your capabilities. Look at these steps and tips and make sure you have the means and will to see the repair to the end.
Make sure that all of the spare parts are available at your local parts shop so you don’t have to wait for the part in order to finish the repair.
If you’re facing more complicated repairs and involves for instance taking off the gas tank, no shame in seeking professional help. Better this then getting into trouble.
So, I hope this article will help in getting an idea of how to fix your fuel pump problem. If it did, grab those tools, start repairing and stay safe.
Written by: Sibin Spasojevic
Former car technician, life-long car and DIY enthusiast, author for Despairrepair.com