How to Start a Car with a Bad Fuel Pump

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how to start a car with a bad fuel pump

Defective fuel pumps are among the most common culprits of start-up failures, especially in older vehicles. Like the rest of the automobile, this crucial component can begin to accumulate wear with enough use. Eventually, it may deteriorate to the point where it stops working altogether.

When that happens, the consequences can be highly inconvenient, to say the least.

Fortunately, it’s possible to start a car with a faulty fuel pump and keep it running long enough to get it to a garage for much-needed repairs. The following guide will tell you how.

But first, a quick lesson on fuel pumps and their central role in the internal combustion engine.

What Does a Fuel Pump Do?

As you can probably gather from the name, the fuel pump’s job is to pump fuel from the gas tank to the car engine.

More specifically, the pump works by mixing the liquid fuel with air, compressing it, and directing it through a special relay into the carburetor or fuel injector. There, it ignites and generates the pressure needed to animate the piston and crankshaft and set the vehicle in motion.

Needless to say, the fuel pump is one of the most vital parts of the whole engine.

How a Bad Fuel Pump Affects Your Car’s Performance

When a vehicle’s fuel pump is on the fritz, it’s typical for the engine to turn over but fail to “catch” when you turn the key or hit the starter button. This can occur for one of two reasons:

  1. The broken fuel pump isn’t able to supply the carburetor or fuel injector with a sufficient amount of fuel.
  2. The engine’s delicate air-fuel ratio (roughly 14.7:1, or 14.7 grams for air for every 1 gram of fuel, in case you were wondering) is off.

Either way, the result is often that your car becomes an oversized paperweight, and you’re left stranded in your driveway—or somewhere far less safe.

Where Is The Fuel Pump Located?

The fuel pump is submerged in the fuel tank. It sits there ready to draw the fuel out of the tank, force it into the fuel line, and transfer it to the engine.

If you go around to the back of your vehicle and look under the rear bumper, you’ll see a bulky hunk of metal fastened to the underside of the car with metal straps. That’s the fuel tank. The fuel pump is inside, and it may not be easy to get to if you don’t have any experience working on cars.

While replacing a bad fuel pump isn’t a particularly difficult project, it’s one that needs to be performed carefully, as even small mistakes could lead to even more challenging and costly repairs.

To ensure the job gets done right the first time, we strongly recommend having a qualified automotive expert diagnose and remedy issues with your vehicle’s fuel pump.

Signs of a Struggling Fuel Pump

fuel delivery system

Failing fuel pumps have a way of letting vehicle owners know they’re on their last legs. Here are some telltale symptoms to be on the lookout for:

A sputtering engine

Sputtering, coughing, and other unusual noises coming from your car’s engine compartment could be an indication that you’re dealing with a faulty fuel pump motor. In some cases, you may hear these noises emanating from under the driver’s seat, which is where the fuel line runs.

Engine surging

First, your engine stalls or loses power. Then, it revs up suddenly, only to die down again a moment or two later. This happens because the engine is only receiving spurts of fuel rather than a constant influx.

Poor fuel economy

If it seems like your vehicle isn’t getting the kind of mileage that it used to, it doesn’t mean that you’re going crazy. You may be dealing with a worn-out fuel pump that’s yet to begin exhibiting more serious side effects.

Excess engine heat

Unexplained overheating is common with fuel pumps. Your vehicle’s “Check Engine” light may come on.

How to Start Your Car with a Bad Fuel Pump

air mattress pump

Now that you have a better idea of what your vehicle’s fuel pump does and how it works, it’s time to learn how to coax it into compliance—at least for a short time.

Remember that the following procedures are temporary stopgaps meant to help you get your car to an auto repair center. They’re not permanent solutions. Force-starting a vehicle with a bad fuel pump is not ideal, and driving it more than a few short miles can further strain the fuel pump or even do severe damage to the engine.

Method One: Check for a Blown Fuse

This first fix will help you determine whether the problem is the fuel pump itself or one of its electrical regulators.

After confirming that your vehicle is completely off, pop the hood and hunt around in the engine compartment for the black-covered fuse box. You should find it off to one side of the battery.

Consult your owner’s manual to figure out which fuse corresponds to the fuel pump. Once you’ve identified the correct fuse, remove it from its slot and inspect for signs of visible damage. A blown fuse will usually be recognizable right away.

If the fuel pump fuse appears to be intact, your next step will be to test whether it’s receiving power. You can do this by hooking a multimeter up to the empty fuse slot and measuring the electrical output. If the readout shows a number greater than 10, you can at least be sure that there’s nothing wrong with the fusebox.

Next, test the actual fuel pump connection. You’ll find this key wiring component just above the fuel tank at the rear of your vehicle. For this phase, you’ll need to turn on your car’s battery to ensure that there’s electricity flowing to the pump.

Ground your multimeter’s negative (black) lead by securing it to any exposed metal surface on the vehicle’s underside. Use the positive (red) lead to test each prong inside the fuel pump connector. If any prong gives back a reading of zero, it means that your fuel pump has an electrical issue.

Method Two: Reset Your Fuel Pump Manually

Once you’ve ruled out a blown fuse, you can try resetting your fuel pump using your car’s inertia switch, which essentially acts as a killswitch for the fuel pump in the event of an accident.

Depending on the make and model of your vehicle, the inertia switch may be hidden inside the central console, behind the glove box, under the front seats, beneath the driver- or passenger-side kick panels, or inside the vehicle’s trunk or luggage compartment.

When you find your inertia switch, you’ll notice that it has a big red button on it. Under normal circumstances, this button should already be depressed.

Give the housing a whack with a screwdriver or another tool to spring the button (don’t worry, it’s designed to release when exposed to direct impact, as often happens during collisions), then press it in again. Doing so will reset the fuel pump and possibly buy you enough time to get your car to the nearest repair center.

Method Three: Use a Fuel Pressure Gauge

If you happen to have a fuel pressure gauge handy, connect it to the tapered Schrader valve on the curved metal beside your fuel rail. Miraculously, this may allow your car to start where it wouldn’t before.

The reason why is complicated and involves a lot of technical jargon, but you can just think of it as a neat bit of motor magic.

If you manage to get your vehicle started, let it idle for around 10 minutes and see whether the psi drops in that time. If so, you almost certainly have a leak on your hands.

Method Four: Pump the Fuel to the Engine by Hand

Let’s say you’ve tried all of the preceding methods, and none of them have produced the desired result. That only leaves you with one course of action: providing the necessary pressure yourself.

All you’ll need to pull off this nifty automotive hack is a screwdriver and a manual air pump like the kind used to blow up an inflatable mattress—fair warning: things may get a little messy.

Open your hood and locate the fuel line running to the engine. Use your screwdriver to disconnect the line, setting the cylindrical fuel filter aside. Then, insert the nozzle of your hand pump into the fuel line and give it three to four good pumps. This may be tough, as you’ll most likely encounter resistance within the line.

Here’s where it gets tricky. As quickly as you can, remove the pump from the fuel line, reattach the filter, and feed it back into the engine. You’ll have to do this fast, as the introduction of external pressure will cause the stagnated fuel to come gushing out of the line.

After you’ve finished reassembling the fuel line, wash your hands thoroughly, cross your fingers, and try starting your vehicle. With any luck, it will rumble to life, and you’ll be on your way.

How Much Does Fuel Pump Replacement Cost? 

fuel pump problem

If you’re unable to fix the fuel pump yourself, you’ll have to visit a mechanic. A fuel pump replacement costs between $220 and $1,062 on average, depending on the car’s age. Labor expenses are roughly between $124 to $260, with parts costing $95 to $854. Taxes and fees are not included in the estimates.

Maintaining your fuel pump

There are a few things you may do to keep your vehicle’s fuel pump in good operating order, whether you’re using an electric or mechanical gasoline pump. Furthermore, here are some measures you can take to ensure that your car’s fuel delivery system is in excellent working order:

Change your fuel filters!

This is one of the most critical aspects to fuel pump maintenance. The fuel filter acts as a screen for your car’s engine, which can be both helpful and harmful. If you change your fuel filters regularly, then the odds are that you will avoid having debris in your fuel system that might otherwise damage your vehicle’s components. Fuel filters should be replaced every 24,000 or once every 2 years.

Fuel injection cleaners

Using fuel injector cleaners can also help maximize your car’s overall efficiency. These products are designed to clean the engine of any built-up grime that might hamper performance, or damage your vehicle in the long run. Fuel pumps are critical components to your car because they move life-giving gas into the combustion chambers for efficient operation. Cleaning the fuel injectors will allow for maximum efficiency.

Ethanol is a growing issue for many cars and trucks on the road. Ethanol can’t be burned as efficiently as normal gasoline, so it puts stress on your entire fuel delivery system, including the gas tank, fuel pumps, and injectors. Agents like STA-BIL Diesel Alcohol Treatment (and its non-alcohol alternative) are designed to keep ethanol at bay by bonding with any of the alcohol molecules that may be found in your car’s fuel lines or storage tank.

Applying these tips will help ensure that your vehicle’s pump is well taken care of and properly maintained: however, if you suspect there is a problem with your pump, be sure to visit a mechanic immediately to avoid driving around with an underperforming pump.

Wrap Up

There you have it—four different DIY strategies for starting your car with a bad fuel pump.

Hopefully, one or another of them will prove successful. Assuming that it does, remember to head straight for the shop. An experienced technician will address the root of the problem and make sure it doesn’t happen again so you can go forth and cruise with confidence.

FAQs

Can a car drive with a bad fuel pump?

No, it is not safe to drive with a bad fuel pump because when a fuel pump isn’t working properly, it won’t be able to supply the fuel system with constant fuel pressure. This means your car won’t start, stall, or it can even shut down at any time.

Will a bad fuel pump cause a car not to start?

Yes, a bad fuel pump is one of the most common causes for vehicles to not start. When the fuel pump on your vehicle cannot supply gas from the tank to the engine, you will have difficulties starting it. Because the pump is unable to push enough gas through, the car will struggle to start and run. A worn pump’s pressure drops, leaving the engine without gasoline.

Will a bad fuel pump throw a code?

Yes, if the car’s computer detects that the fuel pump is not working properly it will throw a code to let you know. Your ECM will record a code of P0087, this means that the fuel pressure in the system is below specification.

How is fuel delivered from the tank?

This depends on the type of fuel pump that is being used. A line with a suction draws fuel from the gas tank through a small motor, which drives an electrical generator to power electric fuel pumps. Mechanical gasoline pumps, on the other hand, move when the crankshaft spins and draw gasoline via a hose with a sucking function.

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