Q: Engine shakes when I turn on the car for the first time in the day

asked by on

My Pontiac G8 engine shakes every time I turn it on for the first time in the morning but after that the engine doesn't shake any more. I changed the spark plugs but the engine light came on it had come up a few weeks back but I cleared the code disconnecting the battery. Now the check engine light came up again? And the engine still shakes when I turn it on?

My car has 89000 miles.
My car has an automatic transmission.

Hi, thanks for writing in. I’d be happy to provide my insight.

Most likely the fuel pressure is dropping off as it sits overnight. This is a fairly common problem. I’m wondering what the code that was being set was. I would think it would was a random misfire code with this condition though. When the fuel pressure drops as it sits, your motor will take extra time to build fuel pressure. You can test this theory by cycling the key several times before you attempt to start it. Each time you cycle the key, leave it in the run position for at least five seconds, then turn it off. The fuel pump will only run for a few seconds if the motor is not started. Many GM vehicles won’t turn the fuel pump on for as much as a minute after the first key cycle. If you turn the key on an listen for a pump noise coming from the fuel tank, you can confirm it the pump is turning on.

If this makes your car start better in the morning, the next thing to do is locate the source of the internal fuel pressure leak. It will either be in the fuel tank, a fuel injector or the fuel pressure regulator. Although, if it is the regulator, the car will always run very rich, most likely spewing black smoke out the tail pipe.

This is by far the most likely cause for your problem. Anything else will require an experienced technician to diagnose your car as it will not be an obvious problem requiring the use of sophisticated equipment and extensive knowledge of all the car systems. For this reason I recommend the following inspection to help you figure this out: Car is hard to start inspection

If your car does have a loss of fuel pressure, it will take some diagnosis to determine where the pressure loss is occurring. This is usually a creative process that will be specific to your car. I hope this helps and best of luck!

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 shakes when I turn on the car for the first time in the day

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: Engine shakes upon startup.

I can be quite alarming to start your car and have the engine start loudly shaking. There are a number of reasons why your Ford Focus is experiencing these symptoms. I have seen a number of shaky engines due to...

Q: Alternator belt hardly lasts more than two days. Meanwhile, when ever the belt is changed, it works well for two days again

Hi there - if the belt is failing within 2 days of driving, there is a problem with one of the components driven by the belt (alternator, AC compressor, water pump), the belt tensioner, or an idler pulley. If the...

Q: P0089 code, fuel pressure regulator performance low. Went into limp mode, then next morning no start

After doing a little research on your particular situation, it looks as though this is a fairly common problem with this model of vehicle. I would suggest contacting your local dealership about the situation due to the fact that I...

Related articles

P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.