One of the most frustrating things about a car is the car won’t start after getting gas or the car is taking multiple tries to start after refilling with gas. Another annoying condition that car owner faces is that the car sputters when started after getting gas. This post explains how to troubleshoot a car that won’t start after filling it with gas. It covers common problems and solutions to get your vehicle back on the road. This post explains how to troubleshoot a car that won’t start after filling it with gas. It covers common problems and solutions to get your vehicle back on the road.
A car won’t start, sputters or stalls after getting gas when a gas cap is not properly tightened or the EVAP purge valve is stuck open that is causing a large amount of fuel to be sucked into the engine. It will disturb the air/fuel ratio of the combustion mixture and prevent the car from starting after getting gas.
A few days back, I faced the same issue with my car. I replenished my car with fuel but the car was not starting. I checked the battery, connections of battery, alternator, starter motor, and wirings. Everything was fine. The battery was fully charged, and the wirings were showing correct voltages when checked with a multimeter.
So, after spending tons of hours and reading suggestions by experienced people on relevant forums, I found that if your car sputters or takes multiple tries to start after getting gas then the problem most likely lies within the fuel system of the car.
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Why Doesn’t the Car Start After Filling Up Gas?
The most common reason a car won’t not start or sputters after getting gas is that the purge control solenoid valve of the evaporative emission control system (EVAP) is partially stuck open which sucks all fuel vapors from the vapor storage canister to the engine. Since extra fuel vapors are forced from the canister to burn in the engine cylinder after refilling a car with fuel, the air-to-fuel mixture becomes too rich with the fuel to support the combustion. As a result, the car won’t start after getting gas.
How EVAP System Works?
EVAP system of an engine works by sucking extra fuel vapors from the canister through the purge valve to prevent leakage of fuel in the environment.
There are the following main components of EVAP system:
- Charcoal Canister
- Purge Valve
- Canister Vent Valve
- Fuel Tank Pressure Sensor
The schematic diagram of an EVAP system is shown in the figure below:
Before continuing, the PCM (powertrain control module) and engine control unit (ECU) are the same terms used interchangeably.
The canister is a small container filled with activated charcoal to trap the fumes of the fuel with the help of activated charcoal.
There is a pressure sensor on the fuel tank that detects any considerable leakage from the fuel tank. The fuel tank pressure sensor sends the data to the engine control unit module.
The purge valve is a one-way solenoid valve that connects the charcoal canister to the engine’s intake system. When the car engine is off, the purge valve is closed. Once the engine is up and running, the ECU continuously and moderately opens the purge valve.
The purge valve is opened by the engine control unit to create a vacuum that pulls fresh air through the vapor canister. The fresh air forces the fuel vapors and delivers them to the engine so that they can be burnt in the normal combustion process.
The vent valve is a one-way solenoid valve that is connected to the canister. The vent solenoid valve is usually open so that air is drawn through the canister where it is mixed with the vapor and then drawn into the engine and burnt. When there is a large leak detected in the EVAP system, the engine control unit of the car will close the vent valve to seal the system during the self-diagnostics of a large leak.
Causes of Car Won’t Start After Getting Gas
Here are the causes of the car won’t start after getting gas.
1. EVAP Purge Valve is Stuck Open
It is a common problem with the fuel delivery system of vehicles, especially after filling them up with gas. The EVAP purge valve is responsible for removing the vapors from the canister and purging them into the engine. It helps in preventing the buildup of fuel gases in the fuel tank.
In some cases, the valve can become stuck open when allowing excessive vapors to enter the engine. When refueling the car, a lot of fumes build up in the fuel tank. A proportion of the fuel vapors, that should be contained in the vehicle’s charcoal canister, are pushed past the open valve and into the intake manifold. When the car is restarted, the mixture is too rich to support combustion.
When there is excessive fuel in the air-fuel mixture, fuel will not be completely burnt, due to which the car takes several tries to start after it is refilled with the fuel. In such cases, you have to step on the gas pedal more to open the throttling valve of the air intake manifold and bring more air into the engine for combustion. If holding down the pedal halfway trick works to start the car, this is the biggest sign that you may need to replace the purge valve.
To diagnose a faulty purge solenoid valve, you can do the following steps:
- Locate the purge valve by taking help from the owner’s manual.
- Bypass the purge valve by temporarily disconnecting it from the intake manifold. Now, start the car. If the car readily starts, it means that the purge valve is faulty.
- Next, remove the purge valve from the car. You either need a spanner/screwdriver to remove the purge valve or you can simply remove it by rotating it anticlockwise with your hands.
- After removing the purge valve, if you can blow through it in either direction it means that the purge valve is confirmed faulty.
- Another bulletproof test you can do to diagnose the purge valve is to pull the vacuum on the side of the purge valve that goes to the intake manifold through the vacuum pump. This is the same side of a purge valve through which the intake manifold of the engine creates the vacuum to suck fuel vapors from the canister. If the purge valve is not holding a vacuum, it means that the purge valve is faulty.
Check out the below video for a diagnostic test of a purge valve.
2. Clogged Fuel Filter
If you notice that your car isn’t starting after refilling with fuel, you might want to check the fuel filter. Fuel filters remove dirt, water, and other impurities from the fuel before it enters the engine. When the fuel filter gets clogged, it does not allow the fuel to pass through. This can cause poor engine performance and ultimately affect the car’s ability to start. A clogged fuel filter can cause low engine power and poor fuel flow. Moreover, a clogged filter can also increase the chance of the engine running rough.
You would need to change the fuel filter of your car every 20,000 to 30,000 miles, based on the recommendations in your owner’s manual. It is also important to use high-quality fuel to keep the fuel circuit of your car clean.
3. Faulty or Clogged Charcoal Canister
The charcoal canister is responsible for capturing the fuel vapors. If the bed of activated charcoal in the canister is clogged with dirt, the fuel vapors from the fuel tank will not go to the canister. Instead, all the fuel vapors will flow back to the fuel tank, which will make it difficult to refill the fuel tank.
So, if the charcoal canister is unable to hold the fuel vapors, the excessive amount of fuel vapors will pass through the purge valve, due to which the car will take several tries to start after getting gas.
Here is how to diagnose a faulty charcoal canister:
- Locate the charcoal canister in your vehicle’s engine. It is normally connected to the purge valve from the bottom.
- Visually inspect for cracks or damage.
- Now remove the charcoal canister from the engine.
- Connect the hose to the port of the charcoal canister which is connected to the fuel tank.
- Blow the air through the hose.
- If the blown air does not come out of the other ports on the charcoal canister, it means that the charcoal canister is faulty.
Check out the below video to understand how to remove the charcoal canister.
4. Faulty Fuel Pump
A fuel pump in the engine is responsible for pumping a sufficient quantity of fuel into the fuel injector. The fuel pump is usually located on the fuel tank. In some engines, the fuel pump is located in the fuel line. If you have a faulty fuel pump, your car will not start. It may even stall or die. A faulty fuel pump can be caused by several factors including old age, mechanical defects, electrical problems, and improper maintenance.
Fuel pumps do not last forever. That’s why vehicle manufacturers recommend replacing a fuel pump after every 60,000 – 100,000 miles.
Here are the symptoms of a faulty fuel pump in a vehicle’s engine:
- Sputtering noise of car when speed is high
- Whining noise from the fuel tank
- Engine is starved for fuel when accelerating
- Reduced gas mileage
There is a relief valve on the fuel pump that prevents excess gasoline from flowing into the engine intake manifold. When a relief valve on the pump fails, the excessive fuel would be fed into the engine system, due to which the gas mileage of the engine is reduced.
Here is how to diagnose a fuel pump:
- Turn the ignition on
- Open the gas cap of the fuel tank
- If you do not hear the sound from the fuel tank, it could mean the fuel pump is not running
- Now, turn the ignition off
- Locate the fuse box and find the fuse for the fuel pump with the help of the fuse box layout diagram of your vehicle
- If the fuse of the fuel pump is fine, check the relay of the fuel pump in the fuse box
- If the relay clicks, it means that it is fine
- Now, turn on the ignition
- Next, check the pressure of fuel using the fuel pump pressure test kit
- Locate the test port on the fuel line
- Fit down the hose of a pressure test kit on the test port
- If there is no fuel pressure on the test gauge, it means that the fuel pump needs to be replaced
Check out the below video to understand how to diagnose the fuel pump.
Conclusion – Car Won’t Start After Getting Gas
To recap why the car is sputtering or not starting after getting gas, here are the following causes:
- EVAP Purge Valve is Stuck Open
- Clogged Fuel Filter
- Faulty or Clogged Charcoal Canister
- Faulty Fuel Pump
Why does my car sputter after getting gas?
A car sputters after getting gas because the vehicle is having problems with the fuel system. Dirt and debris can enter the system through the fuel filter, pump, or fuel injectors. When this happens, the engine runs inefficiently and sputters.
How do you prime a fuel pump after running out of gas?
The best way to prime a fuel pump is to turn the ignition key on after filling the tank. Wait for few minutes. Turn off the ignition. Again wait for around 2 minutes, and turn on the ignition. Repeat this procedure a couple of times to successfully prime the fuel pump. Priming a fuel pump make sure there is adequate pressure in the fuel line from your gas tank all the way to the fuel injectors.