04 Malibu fuel pressure questions

[wcamaddox]

Ok here is my question and I hope somebody can help. My wifes Malibu every once in a while has a problem starting. So when I changed the oil I put the furl pressure gauge on it. The pressure came up to approx. 55 psi and than I shut off the key. After the amount of time it took to change the oil the pressure had bled off to about 40 psi. Is this normal or do I have a bad pressure regulator. And if it is the regulator is it part of the fuel rail like the old school 2.8 & 3.1 mpfi? Also does this bastard even have a fuel filter? Just wondering and thanks for the help in advance.

Bill
P.S. its a 3.5

[NocturnalCreations]

What year is your wifes malibu and what motor does it have?

When it fails to start does it crank but not start?

When you first shut off the car was the pressure still at 55psi?
If it was then you lost pressure during your oil change you probably have a leaking injector, bad return line or fuel pump.

I dont think the pressure regulator can make you loose pressure unless its leaking, wich you would see...or possibly leaking into the return line, im not sure about that one

Do you smell gas? If so look between the upper and lower intake around the injectors for puddles of fuel.

[wcamaddox]

2004 Malibu with a 3.5
doesnt fail to start just turns over a bit than starts like the fuel pump needs to pump up to pressure.
Didnt start the car just turned the key on to check pressure and turned the key off to see if it maintained pressure. The pressure was at 55 until just a little bit later and it started leaking down.
No smell of gas even under the car inspecting the return line. Its plastic so I wanted to make sure that wasnt a problem no kinks and no signs of the fuel leaking from it. If my injectors were leaking wouldnt it foul a plug? None of the plugs were fouled and actually all had a nice color to them. I know the older 60 degree MPFI pressure regulators would leak into the return line I had one on a cavalier that would, had me beating my head against a brick wall on that one.
Just unsure if this car even has a regulator under the intake plenum or not kind of hard to see.

[NocturnalCreations]

Put your fuel pressure gauge back on. Prime the fuel pump and watch the gauge. Note how long it takes for the pressure to build. It should be fast. Once the pressure is up to 55psi or whatever the peak pressure is, try to start the car. If the car starts right up, do it all over again but let the car sit till the pressure drops again. Now try to start it without waiting on the pressure to build up.

Im half awake right now so bare with me.

If the car wont start right up with the pressure at its peak then it has to be an ignition problem(assuming because its an 04). Lets hope its not another passlock issue. If the pressure takes too long to build up, the car will crank for a few seconds before it starts when you try to start it normally. It could be the filter, leaking injector, pump etc. that makes the pressure build up slow....

anyway let us know what happens with the pressure test. Im just trying to eliminate parts...like passlock and pump.

[beautiful_eyes]

What is a passlock issue and how much is that?

[NocturnalCreations]

Read here on passlock
http://www.automotiveforums.com/vbul...d.php?t=454520

[wcamaddox]

I hope its not a passlock issue either, I had read through that before I posted my question because I hate asking questions someone else may have already resolved. I will let you know on the starting under low pressure on Monday(I work 12hr days and this is my 3 day weekend to work), it seemed to me when I turned the key on it didn't take very long to build up pressure and I have told my wife to let it wait a couple of seconds with the key on before engaging the starter, she has a bad habit of putting the key in and immeadiately trying to start the car and getting upset when it doesn,t start right now. Trying to train her but it takes a while......

[NocturnalCreations]

Thats funny.

[slls]

Originally Posted by wcamaddox

2004 Malibu with a 3.5
doesnt fail to start just turns over a bit than starts like the fuel pump needs to pump up to pressure.
Didnt start the car just turned the key on to check pressure and turned the key off to see if it maintained pressure. The pressure was at 55 until just a little bit later and it started leaking down.
No smell of gas even under the car inspecting the return line. Its plastic so I wanted to make sure that wasnt a problem no kinks and no signs of the fuel leaking from it. If my injectors were leaking wouldnt it foul a plug? None of the plugs were fouled and actually all had a nice color to them. I know the older 60 degree MPFI pressure regulators would leak into the return line I had one on a cavalier that would, had me beating my head against a brick wall on that one.
Just unsure if this car even has a regulator under the intake plenum or not kind of hard to see.

The fuel pressure regulator is built into the fuel pump assy at the fuel tank. One line system with no filter in the fuel line.

[beautiful_eyes]

i dont have anti-device, so i guess i can rule this out...

[beautiful_eyes]

hmmm, maybe i should try that, but we shouldnt have to do that, i mean the car should just turn over,,,will u let me know too?

[beautiful_eyes]

i sometimes smell gas when i start it, after the 5 seconds of starting the b@#$%! i would think the computer would sense fuel injectors bad......i know i have a #4 spark plug and wire bad, mind u i just had them change and the parts are junk, but this wouldnt cause it.

[wcamaddox]

Yeaaahhh!!! Just what I wanted to hear all that crap is one unit and in the fuel tank no less...... you know sometimes engineers can be so fu@#&%^ stupid it amazes me. Hell my dads an engineer he BUILT a car while he was in school (1930 model A) and the darn thing is so easy to work on its not funny. Just not very safe......