my car cranks but doesn’t start.

my car cranks but doesn't start. I unplug the fuel pump then it starts. I've already changed the fuel pump and also, It's not because of the anti-theft.
Experienced mechanics share their insights in answering this question :
You’re starting it after unplugging the fuel pump? It won’t stay running very long before your engine stalls out again! You may have a bad fuel pressure regulator that is dumping fuel into the intake causing the engine to flood when you first try and start the car.

Depending on the vehicle and engine the fuel regulator will have a vacuum line on some designs. Disconnect the line and turn they key on to see if fuel comes out. If it does then replace regulator. If the regulator is on the spider inside of the intake then leak the fuel pump connected to it. Then try holding the gas pedal to floor and see if it starts and stays running. You may have a bad spider and regulator in this case.

If you decide to get this fixed, consider YourMechanic, as a certified technician can diagnose your starting issue firsthand and help you replace your fuel pressure regulator as necessary. Good luck.

How to Identify and Fix Common car Problems ?

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If the car cranks when you turn the key, but the engine won`t start, it could be because fuel isn`t getting to the engine. One potential reason for this could be dirty fuel injectors. Over time, the fuel injector nozzles can become clogged with rust, corrosion or debris.
If the fuel pump fails completely — to the point of not being able to provide enough fuel for the engine to run, the vehicle will refuse to start. The engine will still crank when the key is turned, but it will be unable to start due to the lack of fuel.
Often it is, but any number of things can prevent an engine from starting. These include a bad fuel pump relay or control module, a blown fuse, a wiring fault, loose or corroded wiring connector at the pump, or even an issue with the anti-theft system.
There are many causes of hard starting but illustrative ones are a faulty engine coolant temperature switch (sensor), malfunctioning idle air control (IAC) valve, vacuum and EGR leaks, inadequate fuel delivery or pressure (clogged fuel filter, injectors), and contaminated or old gasoline.
If your car`s fuel pump has gone bad—but hasn`t completely stopped working—you should still be able to start it by applying manual pressure, attaching a fuel pressure gauge, or making sure the engine receives consistent heat.
Just because you hear the fuel pump run does not mean it is pumping the correct pressure to the injection system. If the pressure is real low or the filter is plugged solid, then the pump may not get enough fuel to the fuel rail. The only way to know is to test the fuel pressure at the fuel rail test port.
The most common cause of fuel pump failure is frequently running the tank low on fuel, which causes the motor to overheat. The second most common cause is fuel contamination, usually dirt and rust particles that clog the fuel strainer and prevent the pump from drawing enough fuel under high engine load.
Step 1: Turn the key to run position. Locate the reset button to the fuel pump shut off switch. Press and hold the reset button for about 20 seconds. Note: The fuel pump shut off switch reset button is usually located either under the dash in the driver compartment or under the driver or passenger seat.
Why your car struggles to start but runs fine. There are a number of reasons why your car might be slow to start but runs as-normal once it gets going. Causes can vary from weather conditions to battery health, wiring issues, starter motor concerns and fuel-pump health.
An effective method to determine whether it`s your battery or alternator that`s gone bad is to connect jumper cables from a running vehicle`s battery to yours. After a few moments, try starting your vehicle. Once it`s started, remove the jumper cables — if your engine stalls, your alternator has probably gone bad.
When you attempt to start the vehicle, is there a clicking sound, but it won`t turn over? That may be a good sign. If a jump gets the car running, but won`t turn over again once it`s shut off, a dead battery is likely the cause.

Relevant Questions and Answers :

the most relevant questions and answers related to your specific issue

My car will not start Intermittently. I purchased a new battery 2 weeks ago and yesterday the car wouldn’t start. Got a jump and
ANSWER : The issue you are having is probably due to an intermittent fault in the starter motor itself or a deficiency in the starter electrical circuit, for example a large voltage drop due to a poor ground or a high resistance connection. These issues can be readily diagnosed and resolved on a mobile basis if you request a hard starting diagnostic. If you request that diagnostic, the responding certified mechanic will get this resolved for you promptly. Based on Toyota’s Factory Service Manual, the battery should not be disconnected if the vehicle engine is running. The battery acts as a large resistive voltage sink and consequently taking the battery out of the circuit, while the alternator is still running, can create a voltage spike on the car’s electrical system which is not good for voltage sensitive components such as the engine computer. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.

My car starts fine but always like once a month it doesn’t start it cranks ok but it will not start if I let it sit for 6 hours
ANSWER : Hi There,
What you are describing sounds like an ignition coil that may be failing. Ignition coils are prone to this type of erratic functioning or heat cycling when they are beginning to fail due to the temperature fluctuations under the hood which ultimately cause them to shut down causing the car to only run after cooling down for 30-40 minutes. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeatedly The insulation develops small fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil’s ability to function. This process will repeat itself continuously until the coil ultimately fails completely and must be replaced. I would recommend having a professional from YourMechanic come to your location to diagnose and inspect your ignition system.

When I go to crank my car the key stays in the start position and the car is constantly trying to crank itself.
ANSWER : First, let’s make sure about some terminology before I proceed. I will assume the motor is actually turning over. If the car is trying to start, the motor has to be turning over or it is not trying to start. This is an important distinction when diagnosing the starting system. As a technician, I go to different parts of the system based on this description.

If the key is stuck in the start position, this is a ignition lock cylinder issue and the reason the starter continues to turn the motor over. If the starter is turning but the motor is not, then the starter is likely the problem. Either that or the teeth on the flex plate are all gone. This would require removing the transmission to repair.

If the car runs intermittently, this can be a big challenge. And it also means the starting system is working. It will need to be diagnosed when it is failing. A working car cannot be diagnosed because there is nothing wrong. Where you park your car should not have any affect. It certainly could be a wiring problem. Wiring problems hide really well and can happen anywhere in the miles of wires that are in your car. Isolating the system that is failing is really important here. At the moment I am unsure which system is failing. Starter system, ignition lock cylinder and or ignition switch electrical or something with the engine control system.

When the car is failing, you need to check for spark and fuel pressure. If neither is present, this is a clue. Usually the crank sensor will do this. Does your car have a tachometer? If so, does it move at all when cranking. This is a clue whether or not the cam and or crank sensor is working. Is there a Check Engine Light on with the key on? If there is a Check Engine Light, the code or codes can be used for specific diagnosis.

All of these concerns will send you down a diagnostic path. Be sure not to confuse yourself by misinterpreting multiple system failures. If the key does stick in the start position, this would be the first problem to solve. After that, does the motor actually turn when the starter turns? After that, the question of "Why won’t it start?" is first answered by finding what the motor is lacking. Fuel, spark etc… Good luck.

If you need assistance with these checks, contact a certified mechanic who has the tools and experience needed to properly diagnose this starting issue with your car.

Car won’t crank when it’s cold and now won’t start at all
ANSWER : Hi there:

Usually this issue is cased by low cranking amps inside the battery. If you’ve recently had the battery replaced, it’s possible that an electrical component that makes up the charging system might be damaged or faulty. It’s also quite possible that the main electrical relay or the starter relay is giving you fits. To know for certain what the exact issue might be on your 1989 Toyota Camry, you should have a professional mobile mechanic complete a car is hard to start inspection, so they can pinpoint the source of your issues and recommend the right repairs.

Map sensor car won’t start up good ?
ANSWER : Your MAP sensor is an important input for your computer. It helps determine the load on the engine to calculate the correct amount of fuel to inject. It sometimes takes a few seconds for the vehicle to realize that the sensor is not producing a good signal.

At that point, it will use other methods to determine the fuel rate, such as pre-programmed fuel maps, throttle position, etc. I would suggest replacing the MAP sensor and retesting. If you would like to have it checked first, a certified technician from YourMechanic will be able to scan your vehicle and test components to determine the root cause of your starting issue before making a repair.

I have a 1992 Honda Accord EX and I’m having an issue with the car not having power to the dash at all and doesn’t start.
ANSWER : Hi there:

The symptoms you’re describing are often an indicator that a problem exists with the alternator or charging system such as an electrical relay. Before you spend another penny trying to chase the symptoms by purchasing more parts, it’s best to have a professional mobile mechanic complete a battery does not hold a charge inspection. This service will allow them to correctly diagnose your Honda Accords issues.

The car crank but won’t start
ANSWER : Hi there. This does sound like an issue with the wiring. If the check engine light is coming on every now and then this means that when it does not come on there is no power to the computer. This can be the wiring harness issue or an ignition switch problem. I would have to test for voltage to the computer when the problem is occurring to be able to find where the issue lies. If you need assistance, a certified YourMechanic technician can be dispatched to your location to inspect your vehicle’s non-start issue and suggest any necessary repairs.

car hesitates when trying to start the car ,but when started then i shut car off and start again it will start right up
ANSWER : Hi there:

Sometimes when you have problems starting an engine initially it is caused by a restriction in fuel flow; caused either by clogged fuel injectors or the throttle body that needs to be cleaned. Once the fuel starts to flow and engine warms up, it’s much easier to start. However, it could also be an air filter, EGR valve or other components that causes this issue as well, which is why it’s best to have a professional mobile mechanic complete a car is hard to start inspection so they can pinpoint the source of this issue.