Q: Independently decelerating until car stalls when driving greater than 40 mph. Plus there is high RPM's with acceleration and won't always start in the mornings.

asked by on

Niece's car and this is her report of trouble and work done: Beginning 1 year ago in the winter of 2015/16, occasionally car would independently decelerate until stalled at 40 mph or faster. After letting car sit about a minute, it would restart and be drivable again. July '16 she had 4 motor/transmission mounts, transmission thermostat, water pump, and water outlet gasket replaced. Car ran well for 1-2 months until same symptoms returned, plus high RPMs when accelerating, and sometimes car not starting in the mornings. However, car would always start later in the day. In Sep '16, head mounts were replaced and transmission flushed. Symptoms were gone again but for only one month this time. All symptoms returned late Oct '16. Car will not always start later in the day anymore, so that symptom has worsened. What is causing this? Is it the same issue causing all these problems?

Thank you for any information or help you can offer! Amy and niece in Michigan

Her car has 180000 miles.
Her car has an automatic transmission.

Hi there. Check to see if the fuel pressure on the fuel rail and see if the fuel pressure is around 45 to 65 psi. Run the engine up to a higher rpm and see if the fuel pressure drops. If the fuel pressure is dropping then either the fuel pressure regulator is malfunctioning or the fuel pump is not strong enough to keep up with the speed of the injectors. I recommend seeking out a professional, such as one from Your Mechanic, to help you diagnose your engine stalling.

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. Independently decelerating until car stalls when driving greater than 40 mph. Plus there is high RPM's with acceleration and won't always start in the mornings.

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: Car overheats when heater not on

There can be a variety of reasons that your Ford Five Hundred is overheating, even after repairs have been made. While it is possible you are experiencing problems with the water pump, you may have a defective new thermostat as...

Q: How do I know which O2 sensor to change when it sets a code for o2 sensor? 2000 Jaguar S-type

Hi - the description for each Check Engine problem code contains the clues : for a given code - P1647 for example - the description is "Bank 2, Sensor 1". This means the first sensor in the exhaust system -...

Q: Q: power steering issue

If the system was recently opened up to replace any parts, what you are describing is typically a consequence of air trapped in the system, and consequent aeration of the power steering fluid, which builds pressure in the reservoir. Check...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.