Q: Fuel pressure drops

asked by on July 18, 2016

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.

Fuel Pressure Regulator Replacement $111.64 - $903.72 Get a Quote
Fuel Pump Replacement $120.92 - $1186.72 Get a Quote
Car is hard to start Inspection $79.99 - $89.99 Get a Quote

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.

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・Fair and transparent pricing

What others are asking

Misfire at cylinder #6 and EVAP system not ready

Hello. The misfire that you are getting on that cylinder may be caused by a dirty or failing fuel injector. If compression is fine and if there is good ignition then it may be a fuel issue. If the engine...

Won't start. Replaced starter and relay switch, still won't start. Tested battery and it's good.

Hey there, thank you for asking about your 2001 Nissan Pathfinder. You should check fuse number 18 in the fuse panel under the dash. Test the black and yellow wire at the start interrupt relay to see if it gets...

I have a 99 Yukon when I put it in reverse it goes forward. It has only done it twice

Hello and thank you for contacting YourMechanic. Make sure the linkage on the side of trans moves along with the shifter cable as the cable moves. If that's okay, then drop pan and check the linkage to manual valve...

Oil pressure gague on 0 and check engine light on

Hi There, It sounds like one of two things are happening. Either the motor is in fact low on oil or the oil pressure sending unit is not working properly and may be producing a faulty reading. I would recommend...

Where in the car is the fuel pump relay located so I can replace it?

Hello, thanks for writing in to YourMechanic. The fuel pump relay is the orange relay located in the e-box. If you're uncomfortable with this repair, you may want to consider having a professional from YourMechanic come to your location to...

Car will not start. Will only move to ACC mode

This relates to a faulty mass air flow sensor. This is a unit that monitors air intake into your engine as it is mixed with fuel prior to being injected into the motor. When this is not working properly, many...

Car won't start. Battery, starter & fuses ok. Suspect relay behind dash is there an easy way to access this relay?

The starter relay is located under the driver side speaker in the dash, mounted to the firewall. It may be possible to remove the speaker and reach the relay. If you are not comfortable with the repair or would like...

My car won't start, 2006 Chevrolet Impala

You will need to check the power from the starter relay is getting to the starter motor solenoid to actuate the starter. If it does not, then replace the relay and retest. If power gets to the starter but it...

Have a jeep grand cherokee it cranks but has no spark started a few times then nothing what sensor went bad

There could be a bad cam sensor, crank sensor, coil, or even a wiring issue. It would be best to test the components individually to determine which is causing the problem. My recommendation would be to connect a diagnostic scanner...

Related articles

Understanding the GMC Oil Life System and Service Indicator Lights
Car symbols, or dashboard lights, are a car service reminder. The GMC Oil Life System indicates when and what service your car needs.
A Buyer’s Guide to the 2012 GMC Yukon
When When you want a big SUV that can hold its own, come what may, you’ll be happiest with a GMC Yukon. Although the inside of one of these vehicles can sometimes resemble an upscale hotel room, the 2012 GMC...
How Long Does a Fuel Pump Usually Last?
Fuel pumps are a simple and rugged part of the fuel system. They are usually found inside of the fuel tank and are...