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  • SN95 4.6L Mustang Tech

strating problems (fuel related)

  • Thread starter Thread starter holy_cent
  • Start date Start date Mar 8, 2010
H

holy_cent

New Member
Jul 17, 2009
3
0
1
Mar 8, 2010
#1
  • Mar 8, 2010
  • #1
i have a 98' gt and its all stock. Sometimes it just cranks and wont start but i can hear the pump coming on. if i turn the inginition on and off twice (dumping in extra fuel) than it usually helps.....seeing this i put a pressure guage on the fuel rail and found that when i turn the key, i get a spike of pressue but than it immediately goes back to zero and the car wont start....as soon as the car does start however, than the pressure is fine.....i had to replace the fuel pump a couple months ago but this problem has been happening since before i replaced it. not sure what is causing this problem so if anybody has any advice than that would be awesome!!!
 

Rickyll7

Member
Dec 16, 2005
718
4
19
Mar 8, 2010
#2
  • Mar 8, 2010
  • #2
You might have a fuel injector stuck open or a bad fuel pressure regulator.

Cycling the ignition on and off doesn't add any fuel to the engine, it only primes the fuel system so that it is pressurized... unless you are actually cranking it.
 

wmburns

SN Certified Technician
Aug 14, 2009
5,892
514
204
Houston Texas
Mar 8, 2010
#3
  • Mar 8, 2010
  • #3
Leaky fuel injector, bad fuel pump check valve, or bad pressure regulator.

If leaky fuel injector, would expect to smell gas when key cycled.

A bad fuel pump check valve would have to be totally bad to allow immediate presure leak down. Did you replace the entire fuel pump assembly or just the pump?

Possible a bad regulator. Hands down, the easiest part to replace.

In any case, the leak has to be big to have the pressure bleed down so quickly.
 
H

holy_cent

New Member
Jul 17, 2009
3
0
1
Mar 9, 2010
#4
  • Mar 9, 2010
  • #4
i only replaced the pump in the tank. could it be an injector if i dont have pressure at the rails? and i havnt been smelling any gas at all. thanks for the help so far guys. i got some stuff i can check
 
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