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Leak Detection Pump Guides

Leak Detection Pump Buyer's Guide

Summary

  • Your vehicle’s vapor leak detection pump is an important component in your vehicle’s evaporative emission control (EVAP) system. 
  • The EVAP is responsible for keeping fuel vapors contained within the fuel system. 
  • The leak detection pump is made of several components that work together in order to get accurate information on EVAP leaks. It is made of a series of one-way valves, a vent valve, a sensor, a vacuum solenoid, and a spring-loaded diaphragm. 
  • As a part of the EVAP system, the fuel vapor leak detection pump (LDP) pressurizes the fuel system to help the vehicle’s computer or powertrain control module (PCM) detect leaks that permit fuel vapors to escape into the atmosphere.
  • There are a handful of reasons why your LDP might fail to function properly. A ruptured diaphragm, an inoperable solenoid, and a stuck purge/leak detection pump vent valve are the most common cause for LDP failure. Broken vacuum lines or even poor electrical connections can affect the LDP and the rest of the EVAP system as well. 
  • The check engine light or the malfunction indicator light (MIL) will illuminate if the PCM detects a leak or other issues with the leak detection pump. 
  • Depending on the extent of the damage, your mechanic may suggest the replacement of the LDP or other related components. 
  • A replacement LDP can cost around $40 to $250. This mostly depends on the pump’s compatibility with your vehicle’s specific year, make, and model. 

Rapid economic and population growth coupled with the industrialization of public transit systems in the mid-1900s increased the need for personal vehicles as a means of transportation. A byproduct of this boom is the rapid increase in air pollution, which affected not only the environment but also public health. 

In the 1970s, laws were passed and institutions, like the Environmental Protection Agency (EPA), were established to address the growing concern for public safety. This pushed manufacturers to develop various automotive technologies to limit vehicle emissions and comply with the guidelines set by these laws and agencies. 

A vehicle’s emissions control system helps reduce the noxious gases that a vehicle produces. This system uses a variety of components, such as sensors, catalytic converters, and pumps, to help monitor the main sources for these gases (exhaust system, crankcase, fuel tank). It also helps alert the driver of any unusual activity that might affect the vehicle’s performance and emissions test results.

Your vehicle’s vapor leak detection pump is an important component in your vehicle’s evaporative emission control (EVAP) system. Learn more about this component, how it works, and its failure symptoms with this informative guide.

What is a Fuel Vapor Leak Detection Pump?

The EVAP system is responsible for keeping fuel vapors contained within the fuel system. It basically prevents fuel vapors from going into the atmosphere contributing to air pollution and the forming of photochemical smog. 

As a part of the EVAP system, the fuel vapor leak detection pump (LDP) pressurizes the fuel system to help the vehicle’s computer or powertrain control module (PCM) detect leaks that permit fuel vapors to escape into the atmosphere. This component collects, stores, and moves the fuel vapors to the intake manifold so that they can be used for combustion. It also helps monitor the fuel system for blockages and other problems. 

How Does a Leak Detection Pump Work?

The leak detection pump is made of several components that work together in order to get accurate information on EVAP leaks. It is made of a series of one-way valves, a vent valve, a sensor, a vacuum solenoid, and a spring-loaded diaphragm. 

The pump uses the engine vacuum to move the diaphragm up and down. The solenoid controls this up and down motion to pressurize the entire EVAP system. Once the pump reaches a certain amount of pressure, it will stop moving. This closes the vent valve at the bottom of the pump and seals the EVAP system. 

At this point, the pressure in the EVAP system must remain at a certain value. The PCM monitors the behavior of the EVAP system. If there are no leaks, the vacuum solenoid at the top of the pump releases the pressure from the whole EVAP system. This lets the diaphragm push on the vent valve to allow fresh air into the system. 

If the pump exceeds or fails to reach the preset pressure at a given time, it indicates the presence of a leak. Note that the EVAP leak detection pump only indicates the presence of a leak, not its location. This is why close inspection must be conducted to pinpoint the source of the leak or issue.

In some vehicles, the size of the leak may even be detected. The PCM measures the size of the leak by monitoring the frequency output of the reed switch/sensor within the LPD. Faster pressure drops indicate large leaks, while slower pressure drops indicate small leaks.  

The LDP is also equipped with a canister filled with an activated carbon mixture. This canister temporarily contains fuel vapors until they can be transported to the intake manifold for combustion. 

How Does a Leak Detection Pump Fail?

Inspecting the EVAP system for leaks or other signs of damage is important because even a small leak can release harmful vapors into the environment if left unresolved. 

There are a handful of reasons why your LDP might fail to function properly. A ruptured diaphragm, an inoperable solenoid, and a stuck purge/leak detection pump vent valve are the most common causes of LDP failure. Broken vacuum lines or even poor electrical connections can affect the LDP and the rest of the EVAP system as well. 

As mentioned above, the leak detection pump is vital in detecting leaks in the EVAP system, but leaks can also form within the pump itself. The charcoal canister may crack open and let out vapors. In some cases, the LDP fails to function properly due to a loose-fitting or damaged gas cap. 

Most of the failure scenarios detailed in this section are due to regular wear and tear, though corrosion or impact damage may also cause LDP malfunction. This is why you need to have your EVAP system checked or replaced according to the recommended service interval outlined in your vehicle’s owner’s manual.

It’s important to note that as with any problems with your vehicle, proper diagnosis is important. For each trouble code that registers in your vehicle’s memory, there are multiple possible causes. Pinpointing the exact cause will help you come up with a specific, effective, and long-term solution for the issue.

If you’re not confident in your DIY skills and knowledge, it’s best to leave repairs to a professional mechanic. Otherwise, you can refer to repair manuals and databases for proper troubleshooting steps and other helpful tips.

What are the Symptoms of a Bad Leak Detection Pump?

The check engine light or the malfunction indicator light (MIL) will illuminate if the PCM detects issues with the leak detection pump. A diagnostic trouble code (DTC) will also register in the vehicle’s memory as a result of a malfunctioning pump. 

There are a handful of DTCs that are related to a faulty leak detection pump. Below are just some examples from ALLDATA:

  • P0442- EVAP leak monitor 0.040” leak detected
  • P0455- EVAP leak monitor large leak detected
  • P0456- EVAP leak monitor 0.020” leak detected
  • P1486- EVAP leak monitor pinched hose found
  • P1494- Leak detection pump SW or mechanical fault
  • P1495- Leak detection pump solenoid circuit

Problems with the LDP may also affect riding comfort and vehicle performance. You or your passengers may inhale the fuel vapors if it leaks inside the passenger cabin. This may cause a variety of health issues, from nose and throat irritation to vomiting and headaches. You may also notice a decrease in gas mileage due to the fuel vapor leak. 

If one of the symptoms above manifest or if any other trouble codes register in your vehicle’s memory, you’ll need to see a professional for diagnosis and repairs. It’s a good idea to gather information on how to test a leak detection pump even if you are letting an expert handle the job. Depending on the extent of the damage, your mechanic may suggest the replacement of the LDP or other related components. 

Emissions repair can be quite complicated for an average DIYer as troubleshooting steps differ with each vehicle make and model. Also, the fuel vapor leak detection pump location is quite tricky to access, so you might need specialized tools and knowledge to remove and access it. 

How much is a Replacement Leak Detection Pump?

A replacement leak detection pump can cost around $40 to $250. This mostly depends on the pump’s compatibility with your vehicle’s specific year, make, and model. The price also depends on the brand and series of the part. Most replacement leak detection pumps are sold individually. 

If you’re looking for a quality leak detection pump replacement, you can go to CarParts.com for a part that will last you a long time but won’t break the bank. The site offers a wide selection of durable replacement parts at a great price. You can use the site’s search console to enter your preferences and indicate your vehicle’s year, make, and model. 
 

How to Choose the Right Leak Detection Pump for Your Car

How do you know if your car has leaks in its evaporative control system (EVAP)? The leak detection pump is especially designed to detect leaks in the emissions system by pressurizing the EVAP and measuring the time for the pressure to fill the system. If the time interval is short, this implies a serious leak in vehicle's emissions system. Your car's LDP can be located near the gas tank, and can only be accessed by partially removing the vehicle's exhaust system.

Why install a leak detection pump (LDP)?

Leak detection pumps play an important role in car maintenance. Most of the time, leaks can cause more complicated problems that take longer time and greater effort to fix. Finding these leaks before they cause more issues becomes an advantage to you as it will save you more money and time. LDPs are also important indicators that your car has a serious problem-serious leaks can cause fatal accidents, but with a functional LDP, you can avoid these accidents altogether. Other car leaks can also be harmful to the environment which is why a leak detection pump is necessary for any vehicle today.

What to expect from a leak detection pump (LDP)?

Most leak detection pumps nowadays use solenoid circuits for a more accurate reading of leaks. Some LDPs can measure even the tiniest leaks in your car's evaporate emissions system. When choosing the right LDP for your vehicle, make sure that it uses a solenoid circuit, and that it is sensitive enough to detect the smallest leaks. Cheaper leak detection pumps are mostly made of polymer-based materials that can break down due to intense pressure. If you're looking for durability, stainless steel LDPs are right for you, but budget-conscious drivers can always settle for polymer leak detection pumps.

How to Replace Your Leak Detection Pump in 6 Steps

Emissions system leaks are common car problems that can easily be detected by using a leak detection pump. If you suspect that your vehicle has a leak in its evaporate emissions system, it's probably time to install a leak detector that will tell you if there are leak problems to your emissions system. Leak detection pumps works by applying pressure to the emissions system and turning off when a preset pressure rate is reached. If the interval between the turning on and off of the leak detection pump is short, this means that the leak is serious. Installing the leak detection pump can be as easy as 1, 2, 3 if you just follow this short guide.

Difficulty Level: Difficult

Tools you'll need:

  • Wrench
  • Screwdriver
  • 5 mm drill bit
  • Jack stands (optional)
  • New leak detection pump

Step 1: Remove the exhaust system from the three-way catalytic converter (TWC) to its downstream components to avoid damage to the exhaust manifold. Do this by unscrewing the bolts with a wrench and a screwdriver.

Step 2: Detach the heat deflector plate near the left rear wheel with a 5 mm drill bit. Unscrew the plastic nuts holding the deflector in position. If the reflector is blocked by the rear wheel, remove the rear wheel first or use jack stands to create a better clearance below the vehicle.

Step 3: once you see the leak detection pump, disconnect it from the hose clamp using a wrench or a screwdriver. Manually detach the connector from the leak detection pump, and pull it out carefully.

Step 4: Unscrew the leak detection bracket using a screwdriver. Install the new pump onto the bracket and fill in the three screw slots to connect the pump to the pump bracket.

Step 5: Return the bracket back to its former position, and re-connect the hose clamp as well as the connector to the newly installed leak detection pump.

Step 6: Using the 5 mm drill bit, re-install the heat deflector together with the TWC. Remove the jack stands, and test the pump for leak detection.

Removing the TWC in step 1 can be quite a challenge for beginners, so don't hesitate to ask for professional assistance to do this step. Expert DIYers can spend at least 2 hours replacing leak detection pumps, but it can take up to 4 hours for newbies.

Helpful Automotive Resources

P0456 Code: Evaporative Emission System Small Leak Detected
September 15, 2020
P0456 Code: Evaporative Emission System Small Leak DetectedDiagnostic trouble code (DTC) P0456 stands for “Evaporative Emission System (EVAP) Small Leak Detected.” Your car’s computer may set this code if it determines that there’s a minor leak somewhere in the evaporative emissions control (EVAP) system.
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