How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Matt Your Own Question
Matt, Engineer
Category: Car
Satisfied Customers: 21629
Experience:  Honors degree in Mechanical Engineering, worked 8 years as a Formula 1 engine engineer.
Type Your Car Question Here...
Matt is online now
A new question is answered every 9 seconds

The engine revs up to 3000rpm then falls to 1500 rpm when

Customer Question

the engine revs up to 3000rpm then falls to 1500 rpm when the accelerator pedal down. the vehicle is in park.
Submitted: 1 year ago via
Category: Car
Expert:  Matt replied 1 year ago.


you don't say what model and engine size and fuel type the is but I'd say it sounds like a lack of fuel and could be a lack of fuel pressure from the electrical pump atthe tank.

If the connections to the pump are corroded or damaged then the pump could stop at any time or could not be running at full speed. Check that its relay switches in and outand the relay contacts are clean and bright – replace the relay if in any doubt and do the same for the fuse,

Ideally measure the pressure at the injectors and if this is low check the pump as described and also consider changing the fuel filter as if this partially blocked this too will reduce pressure.

Expert:  Matt replied 1 year ago.
do you still need help?