Skip the auto shop - Our mechanics make house calls

Q: Fuel pressure drops

asked by on

I had the fuel pump replaced but when you try to start the engine it cranks for 15 seconds and then starts or starts the second time! The fuel pressure is not being held in the fuel line

My car has 60000 miles.
My car has an automatic transmission.

A: The fuel pressure is held up to the injecto...

The fuel pressure is held up to the injectors by the fuel pump itself. The pump has a one way check ball built into it. The pump will hold the pressure up to the fuel pressure regulator and the regulator should hold the pressure also.

If one or the other leaks, then the pressure will drop and be hard to start. The way to test to see which one is the cause is to block the fuel return line and see if the pressure goes up and does not drop. If it stays up, then the regulator is bad. If it drops, the fuel pump is bad but after this fix re-check to see if the pressure holds since both components can be bad.

After both are checked, and the engine does start each time after, it seems to run real rich then you may have a leaking injector stuck open. This would show up as black smoke when first started and running rough until the excess fuel is cleared. The regulator or pump is the most common problem. Do not rule out the new pump causing the problem. If you would like to have this diagnosed, a certified technician from YourMechanic can come to your car's location to inspect your car's hard starting issue and let you know what should be done.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: 20 amp ignition fuse continues to blow

Hello. All of this depends on what was spliced into that circuit when the engine was swapped out. I usually isolate this problem by disconnecting the circuits in it until it no longer blows. This fuse usually has a problem...

Q: Excessive oil consumption and sooty exhaust

For your 2007 Porsche 911, the piston rings may be letting excessive oil past them causing the soot build up in the exhaust, and causing the oil consumption. There is an acceptable amount of oil consumption, and 1 liter for...

Q: Looks like it will start but it doesn't

Hi, thanks for writing in. This is easily diagnosable because the fault is not intermittent. Based on the symptoms you are describing, you have either a fault in the ignition system or the fuel system. There are some simple tests...

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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
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.
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.