Car starting, dying, and not staying on

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.

ANSWER : Hello – your symptoms suggest that once your cold start features are no longer needed – engine warming up – there is an air "leak" that ruins low speed running. Causes could be a leaking exhaust gas recirculation (EGR) valve, or leak in the air intake. A failing fuel pump relay (burned contacts) could cause similar behavior, contacts become hot, then won’t pass enough current to run the pump. Failing pump can also act this way – gets hot and fails. I recommend a starts, then dies inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.

ANSWER : Hello. The stalling issues you are having may by caused by a variety of issues. Typically these symptoms can be blamed on fuel, spark, or air. Fuel and spark being the most common systems to fail. Starting with the air filter and cleaning the carburetor were good steps to start. You need to take a better look at the spark system. The spark wires can be tested to make sure the plugs are receiving the voltage that they need to be. You can also test the fuel system by spraying some starter fluid into the air intake. If this helps the engine start and run better than before, then you know you have a fuel delivery issue. This may include the fuel pump, fuel filter, injectors, or a clogged fuel line. The shaking is due to the improper combustion happening in the engine. This will be corrected when the engine is running properly. More testing is the only way to know definitively what the issue is.

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.

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.

ANSWER : Hi There,
The idle air control valve is a small valve on the engine’s intake system that reads the air intake as it comes into the motor. This is controlled by the car’s ECM which uses this information to make adjustments to the air/fuel ratio depending on various inputs such as outside air temperature, intake air temperature, load and various other things. As you accelerate, your car’s engine is receiving a much higher dose of fuel than when at idle and conversely, when you let off the gas pedal, there is a sudden change in this fuel supply as a result of your foot letting off the pedal. When this happens, the job of the idle air control valve is to bring this deceleration down to a slow and smooth idle rather than suddenly cutting off the fuel supply causing the motor to die. When the idle air control valve is not working properly, this cause a disruption in this process resulting in the engine not being able to idle properly. I would recommend having a professional come to your location to diagnose and inspect your vehicle.

ANSWER : Hey there. This may also be caused by what is called the fuel pressure regulator. This is a unit that helps to maintain the fuel pressure at the proper level. When this is not working properly, the fuel pump may be pumping properly, but the fuel may not arrive at the fuel injectors at the proper psi. When this happens, this can cause a lean fuel condition which may cause the car to hesitate, misfire, or stall. If you would like to have an expert pinpoint the issue, a certified professional from YourMechanic can come to your car’s location to inspect the hard start problem and confirm which repairs are needed.

ANSWER : Based on the information you gave, it sounds like a possible fuel starvation issue, caused by a partially blocked, in-tank fuel filter or a crack in the fuel pump housing. The remedy would be to replace the fuel pump assembly and filter. The overheating may be caused by several things, including a stuck thermostat, faulty water pump, or even a cracked head gasket. I suggest having a certified technician, like one from YourMechanic, inspect the relevant systems to pinpoint the cause of your vehicle’s hard starting issue and overheating problem.