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  1. #31

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    I replaced the FPR yesterday and upon start up notice right away everything was much quitter. The weather was about 50 out so Ill have to check when it gets cold again.

    Also anyone notice the noise only when their fuel level is 1/4 and less?

  2. #32
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    Quote Originally Posted by akcooper9 View Post
    I replaced the FPR yesterday and upon start up notice right away everything was much quitter. The weather was about 50 out so Ill have to check when it gets cold again.

    Also anyone notice the noise only when their fuel level is 1/4 and less?
    I never operate with the fuel below 1/3 ...kills fuel pump.

  3. #33

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    Hello folks, just wanted to chime in with this issue that I have also been dealing with. First some info, bought the 1999 nbs Sierra 2500 with the 5.3 this past summer in june as a restoral project , had alot of issues one of which was hard starting, this was remedied by replacing the what seems like common problem fuel pressure regulator (delphi unit) and all was good until I started hearing random buzzing at idle, wasn't to bad during the summer but as temps dropped into fall it got worse and worse, figured I had got a bad FPR so i replaced it with a ac delco unit, still no help. I then came across this post, and figured I would begin by replacing the drivers side rail with a brand new one (ac delco) since it was the primary rail where fuel is introduced into the assembly, I had noticed that GM had modified the part by removing the aluminum baffle inside and figured it was a good fix, well it was for about a week , then the damn buzzing came back, seems like everytime I remove the FPR and put a new coat of motor oil on the orings the buzzing stops for 2 to 3 days. As of now I am contemplating on replacing the passenger side fuel rail and also have a fuel pressure tester on the way,maybe the remaining passenger rail baffle vibrating is causing the pressure to pulse at the FPR?.. Ill follow and update this post as this issue continues on. After working on this truck and seeing how many common issues it has I really do believe GM deserves it's bad reputation by using substandard parts and using what I call sledgehammer/meat head engineering. Rusty brake lines,intermediate steering shafts , fuel pressure regulators, power steering coolers, blower motor resistors and the other long list of stuff I shouldn't really be replacing at this trucks age... I wouldn't knock it if it was stuff like starters and alternators but damn. As long as theres plenty of room to work and parts are cheap Ill keep this pig rolling down the road and use it as a learning experience lol...

  4. #34
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    Quote Originally Posted by Project2500 View Post
    Hello folks, just wanted to chime in with this issue that I have also been dealing with. First some info, bought the 1999 nbs Sierra 2500 with the 5.3 this past summer in june as a restoral project , had alot of issues one of which was hard starting, this was remedied by replacing the what seems like common problem fuel pressure regulator (delphi unit) and all was good until I started hearing random buzzing at idle, wasn't to bad during the summer but as temps dropped into fall it got worse and worse, figured I had got a bad FPR so i replaced it with a ac delco unit, still no help. I then came across this post, and figured I would begin by replacing the drivers side rail with a brand new one (ac delco) since it was the primary rail where fuel is introduced into the assembly, I had noticed that GM had modified the part by removing the aluminum baffle inside and figured it was a good fix, well it was for about a week , then the damn buzzing came back, seems like everytime I remove the FPR and put a new coat of motor oil on the orings the buzzing stops for 2 to 3 days. As of now I am contemplating on replacing the passenger side fuel rail and also have a fuel pressure tester on the way,maybe the remaining passenger rail baffle vibrating is causing the pressure to pulse at the FPR?.. Ill follow and update this post as this issue continues on. After working on this truck and seeing how many common issues it has I really do believe GM deserves it's bad reputation by using substandard parts and using what I call sledgehammer/meat head engineering. Rusty brake lines,intermediate steering shafts , fuel pressure regulators, power steering coolers, blower motor resistors and the other long list of stuff I shouldn't really be replacing at this trucks age... I wouldn't knock it if it was stuff like starters and alternators but damn. As long as theres plenty of room to work and parts are cheap Ill keep this pig rolling down the road and use it as a learning experience lol...
    what gets me going is we payed these GM people like wagner a free ride at taxpayers expense. 10 billion dollar loss of our taxes to bail them out. they should have gone thru bankruptcy. after the 1996 year thats when they started a design to fail approach to building vehicles. also NHTSA had / HAS GM people working to protect GM from costly recalls.

    park brake / fuel tank sender / fuel lines/ brake lines /resistor for fan / temp door control / piston slap so bad that they had to put oversized pistons / heads that cracked/rocker springs/dash stepper motors/ TAC failures..just a few of the designed to fail of GM prior to the bail out ///,, then then blamed the owners for abusing the vehicle.

    forgot to mention the defective DEXRON III that ate at the tranny parts when it turned into acid after 20-30,000miles...

  5. #35

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    Well guys I just replaced the remaining passenger side fuel rail and no help, still vibrates and makes noise, what I have found so far is after tracing all the lines and focusing on the fuel filter I remembered the o rings where in bad shape when i replaced the fuel filter this past summer... I am hearing a suction sound from the side heading to the engine rails and an occasional slurp sound when i jiggle the hard lines, I will have to find some orings to order and will update after replacement. Strange thing is it never leaks sitting statically.

    - - - Updated - - -

    Also after conducting a "destructive inspection" of the old drivers side rail I found no signs of hammering only the baffle clicking away when you shake the assy. It is insulated from the rest of the rail by 2 plastic clips and there really is no chance of the metal baffle smacking anything in my case. Good luck.

    - - - Updated - - -

    Another update, after throwing leak detector on the fuel filter connections and seeing no difference I don't think the o rings are bad , not sure what I was hearing last time.. im still going to order the orings and change them... I also put the fuel pressure gauge to use this time, with the engine off and ignition on im getting anywhere between 49-52, if I turn the ignition off and crank again it will increase to 54 with only 1 psi drop after 5 minutes and then steady pressure. With the engine running and breather hose connected on fuel pressure regulator I was getting 49-52 psi with heavy pulsation in the gauge (between 48-52) and with the engine running and breather hose off it was a steady 60 psi solid no pulsing of gauge and engine speed smoothed out. Vibration sound stops when I pull the breather hose from the FPR. Any suggestions would be appreciated.

  6. #36
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    the fuel pump regulator has a vacuum hose to it. when you remove the vac the regulator outputs max fuel pressure. 60 psi is normal. the problem I see is your regulator is not working correctly because you need above 52psi to idle the engine . a good working regulator with a good fuel pump/filter should have 57 psi at idle of 650 rpm.

  7. #37

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    Thanks j cat, am I assuming correctly that since my fuel pressure reads 60psi while disconnecting the vacuum line going to the FPR that my fuel pump is assumed good? I have also noticed on napa autoparts website that they have FPR's with a 50psi rating and the delphi unit they sell is rated at 56.56 psi which I currently have installed, I have also tried an ac delco unit originally after I had discovered my factory fpr defective. Maybe I should try the Standard motor products unit. I am determined to fix this problem and wish to share the progress with everyone as this can be valuable troubleshooting help for what seems like a common problem. Makes me wonder.....GM wouldn't switch over to a returnless fuel setup mid body cycle on these trucks unless there was something fundamentally wrong with the specific setup in these trucks. Any Fuel pressure regulator problem related search on google will always have gm trucks plastered all over the search results..

  8. #38

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    All, thanks for all your posts. I have a 2001 Chevy Silverado 4.8L. I had problems starting unless turned key on-of 1-2 times. As read previously, either leaky check valve, or worse bad injector. I did not need a fuel pressure gauge to know I was loosing pressure. I replaced FPR with Delphi FP10021 because it was the least laborious/cheapest option. As NAPA states pressure rating is 56psi. It did not solve my staring issues. It did not cause chattering. Weeks later, I replaced fuel pump with Bosch 67305. Had air in lines causing chatter, but went away after purging fuel lines. It did fix my start-up problems. But, month’s later, when cold, chatter came back. As read, chatter goes away when vacuum line is removed and fuel pressure reads steady at 60psi (~55psi with vacuum line attached). I will check vacuum tonight and try lubricate o-rings, and test for other vacuum leaks. Additionally, new Delphi FP10021 has set-screw added to housing. Chatter noise did not change from empty to full tank. So, it should not be the fuel pump. But, does not mean the fuel pump does not have a different harmonic. Hopefully, by adding dampening (lubricant) to the FPR, or changing the spring loaded pressure (or vacuum), it will eliminate the chatter. I will let you know.

  9. #39
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    the fpr change I believe was when they went to E85. 1999 should be the same as my 2000 5.3L 56 PSI.

    also with the engine running and all is good the pressure should read this 56/57 psi.....with our vehicles..

  10. #40

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    Quote Originally Posted by sportnot View Post
    All, thanks for all your posts. I have a 2001 Chevy Silverado 4.8L. I had problems starting unless turned key on-of 1-2 times. As read previously, either leaky check valve, or worse bad injector. I did not need a fuel pressure gauge to know I was loosing pressure. I replaced FPR with Delphi FP10021 because it was the least laborious/cheapest option. As NAPA states pressure rating is 56psi. It did not solve my staring issues. It did not cause chattering. Weeks later, I replaced fuel pump with Bosch 67305. Had air in lines causing chatter, but went away after purging fuel lines. It did fix my start-up problems. But, month’s later, when cold, chatter came back. As read, chatter goes away when vacuum line is removed and fuel pressure reads steady at 60psi (~55psi with vacuum line attached). I will check vacuum tonight and try lubricate o-rings, and test for other vacuum leaks. Additionally, new Delphi FP10021 has set-screw added to housing. Chatter noise did not change from empty to full tank. So, it should not be the fuel pump. But, does not mean the fuel pump does not have a different harmonic. Hopefully, by adding dampening (lubricant) to the FPR, or changing the spring loaded pressure (or vacuum), it will eliminate the chatter. I will let you know.
    I had the same issue starting my 2001 suburban. It takes about 3-4 tries in the AM before it fires up. I was losing fuel pressure when engine was off. Thought it was a regulator issue so I changed it. No change and the fuel rail started to chatter. Tried a different FPR from dealer, the same chatter. I just left the second FPR alone. I changed the fuel pump. Fuel pressure held even after engine was off and fixed my starting isse. I am very sure the old fuel pump was still good. The reason why I was losing fuel pressure when off was the built-in check valve on the fuel pump module was bad and not seating properly anymore.
    After driving the burb for a while, the chatter disappeared.
    2011 Chevy Silverado LT 4WD 30k miles
    2001 Suburban 2WD, 5.3, V8 185k miles
    1993 964
    1996 318TI

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