Q: Engine run for a few seconds then dies

asked by on

Put in new fuel pump cleaned the egr also put in new vacum solenoid checked for air leak with smoke machine ....issue is when I start it it runs fine gives gas fine but after a 10 seconds dies if I unplug the intake it runs non stop but with super low rpms if I barely touch the gas it dies

My car has 90000 miles.
My car has a manual transmission.

Usually a vehicle that won’t rev in the manner you are describing is due to a plugged exhaust system. The most common culprit here is a catalytic converter that has come apart on the inside. If this is the case, creating an exhaust leak before the catalytic converter can confirm this. Also, the amount of air that is coming out the tailpipe when the car is idling low. Compare this to another vehicle that is idling normally. If there is very little, a plugged exhaust is likely the issue. Even so, create an exhaust leak to confirm this. Often times, simply removing the EGR valve is enough, but sometimes it is necessary to remove the down pipe coming off the exhaust manifold. Once you have created an exhaust leak, the motor should idle and rev normally, confirming the plugged exhaust theory. Expect it to be very very loud, so don’t do this late at night or in a neighborhood that is sensitive to noise issues.

My first explanation is heavily dependent on the fact that it dies when you touch the throttle, but there are a number of other possibilities here that are not as easy to explain:

  • Flooded motor: A vacuum leak adds more air into the fuel mixture. If this is the case in your situation, I would suspect that the ECT (Engine Coolant Temperature) sensor has failed. When they fail, they usually indicate to the computer that it is -40 degrees Fahrenheit, which makes the computer dump fuel for a cold start. If this is the case, "clear flood" the motor by flooring the gas pedal while cranking. Not only does this allow more air into the motor, but it signals to the computer to go into clear flood mode and it cuts off the fuel injectors until the vehicle begins to run. This often will require extended cranking until the motor starts. Expect black smoke out the tailpipe and some rough running. A scanner that can monitor data will show you what the ECT is reading. If it not ambient air temperature, this is a sure bet.

  • Rich running condition: If the MAF (Mass Air Flow) sensor is failing, it can cause this. The diagnosis of a MAF can be challenging or obvious. It’s also common to have a 5 volt reference problem created by another failed sensor. If this is the case, you will need a scanner to watch the 5 volt reference while unplugging sensors one at a time. You will only need to unplug the sensors that use the 5 volt reference. A wiring diagram will be necessary to identify the correct ones.

  • Jumped timing belt: If this is the case, it can cause all of these symptoms. This is easily checked by taking a compression check of all the cylinders. If the timing has jumped, at least one cylinder will be significantly lower than the others. Then check the cam timing to be sure.

A diagnosis such as this can be challenging, so you might want to enlist the help of a qualified technician, such as one from YourMechanic, who can come out to your home or office and run a thorough inspection to find out what is causing your car to start then quit.

Good luck and don’t give up.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Engine run for a few seconds then dies

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Lost keys locksmith replaced and programmed key started once w ont start agaib

Hi Terri. Thanks for contacting us today. There are a few possible reasons why this would happen, but in most cases, it's due to a security system glitch that activates after the recently programmed key connects to the ECU. While...

Q: 2001 Honda accord ex 4 cylinder stalls when driving

If the crankshaft position sensor has been directly tested, using an automotive scope or real time scanner, and is confirmed to be faulty (as opposed to having a sensor wiring or other fault) it is recommended to replace the sensor...

Q: Check engine light for EGR valve

Hi there, thanks for writing in. Typically when a problem is recognized by the on board computer (ECM), an error code will be triggered that illuminates the check engine light initially. However, this error code is also stored in the...

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...