Artem_kiev

Hello everyone!

Does anyone have the fuel pressure gauge on NA car with stock fuel pump?
The reason I'm asking cause my fuel pressure gauge reads 51 psi at idle, as FSM suggests, but under hard acceleration it gradually drops to 42 psi or so near redline. The car is not FI anymore, fuel system is stock.

Also I've noticed that when I shut down the car fuel pressure slowly drops to maybe 40 psi or 35 overnight and gets back to norm when I start the car.

Are these things normal?
FSM check procedure says only 51 psi at idle and says nothing about the pressure under acceleration.

karlt

I would say your readings are normal. The fuel pump runs at constant speed, and has a built-in pressure regulator, so the pump is trying to output a constant flow at a constant pressure. At idle the engine is using the least amount of fuel, so the fuel flow into the engine is at its minimum. As rpm increases, so does fuel flow through the injectors. This increased flow rate causes the decrease in pressure your gauge measures.

Artem_kiev

Thanks for the answer, got your point.