I donated and asked question, but answer left out full response. PLease answer more fully

Tiny
JAMESV
  • MEMBER
  • 1998 MAZDA 626
  • 160,000 MILES
It seems to be fuel related. I can hear what I believe to be fuel pump when I turn the key on, it hums for aprox. 2 seconds. Does that means its working or? Does it have a fuel relay? And if so where is it located?
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Friday, November 11th, 2011 AT 10:21 PM

11 Replies

Tiny
RASMATAZ
  • MEMBER
Check and test both the main relay and the fuel pump relay in the main fuse block-What exactly is it doing?
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Friday, November 11th, 2011 AT 10:32 PM
Tiny
DRCRANKNWRENCH
  • EXPERT
The humming noise is the fuel pump priming the system to start the car. There is a fuel relay and it is located under the dash on the drivers side.
The fact that the fuel pump turns when you turn the key means the relay is working. If you think you are having fuel pump related issues, it could still be failing.
Even though the pump turns it might not be producing enough pressure to get the engine to performa correctly.
You can genrally borrow a test gauge from an AdvanceAuot or Auto Zone with a deposit. There is a test port on the fuel rail and the gauge will come with a bunch of adapters so you can attach it to the test port and see what the pressure is.
Sometimes the fuel pressure regulator can fail and that will affect the fuel pressure as the need for more increases with engine load and RPMS. The fuel curve gets thrown off when they fail and will perfomr worse the more load or the higher the RPMs. Fuel pump pressure will affect the engines overall perfomrance at any RPM or even at idle.
Let us know if you need any further assistancew.
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Friday, November 11th, 2011 AT 10:36 PM
Tiny
JAMESV
  • MEMBER
It simply will not start. You asked if I could hear fuel pump, I can but only for 2-3 seconds. Is this normal? It does turn over fine but will not start. Its v6- 2.5. Woild relay be markrd EGI relay? I don't see a fuse marked for fuel in anyway.
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Friday, November 11th, 2011 AT 10:42 PM
Tiny
RASMATAZ
  • MEMBER
Do below and let us know what's going on.

Could be a fuel pressure, injectors not pulsing and no spark

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine atleast 3/16 away from ground-have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, Do you hear the fuel pump come On when you turn key on? If not check fuel pump fuse and fuel pump relay if okay-check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, cap and rotor, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it and keep testing
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Friday, November 11th, 2011 AT 10:47 PM
Tiny
JAMESV
  • MEMBER
When it quit me it did start twice(sort of)it started the first time but only for a second or two, second time it started after pumping pedal alot but only ran if you did not touch pedal, then it died and hasn't started sinse. Could that be the regulator? If so where is it located? I donated two more dollars Thank you so far You have been informative.
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Friday, November 11th, 2011 AT 10:54 PM
Tiny
RASMATAZ
  • MEMBER
Lets rule out the fuel pressure before we go anywhere else its important that we know the actual fuel pressure with and w/o the regulator-we move from here
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Friday, November 11th, 2011 AT 10:57 PM
Tiny
JAMESV
  • MEMBER
I'm going to check the fuel pressure tomorrow. What is the norm on the pressure?
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Sunday, November 13th, 2011 AT 10:50 PM
Tiny
RASMATAZ
  • MEMBER
71-92psi
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Monday, November 14th, 2011 AT 1:26 AM
Tiny
JAMESV
  • MEMBER
Thank Yoy guys for the info it has been very helpful.
I'll recomend you to others, I was impressed with your site. One last question, Being it won't start at all does trat rule out the pressure regulator?
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Monday, November 14th, 2011 AT 9:35 PM
Tiny
RASMATAZ
  • MEMBER
Hook the fuel pressure gauge up and turn key On-what is the FP reading-let me know
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Tuesday, November 15th, 2011 AT 5:42 AM
Tiny
JAMESV
  • MEMBER
I replaced fuel pump. In checking fuel pressure, I took a line loose and had no pressure at all. Replaced fuel pump and all is well again. Thank You for your info. Proved very valuable. I have already recommended yourr site to others which have already used it
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Tuesday, November 22nd, 2011 AT 10:51 PM

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