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New fuel pressure regulator - severe vibration!

KE5FKP

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KE5FKP Enthusiast

KE5FKP

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Posted

:)

2000 Silverado Z71 5.3. Had intermitent starved-fuel starts, discovered fuel oozing from split vacuum boot on top of the fuel pressure regulator. So this means I need a new FPR and boot.

 

Could not find a replacement boot anywhere, but I found a scrap of fuel hose that fits snugly, and trimmed off a piece to use in place of the split boot. Double checked all new o-rings, fuel screen replaced, clip installed. Seal is very (VERY) tight to fuel rail.

 

Starts right up eagerly, but when the vacuum hose is reattached to the FPR, a severe intermitent vibration occurs, which resonates all the way down the fuel line to the rear of the truck. Very loud and originating from the new FPR. I thought maybe a vacuum leak, so I applied cable ties, then a hose clamp to the vacuum connection - no good. Vibration subsides upon removing the vacuum boot from the FPR. In fact, the motor starts/runs great without ever attaching the vacuum line. :banghead:

 

I'm about ready to declare the FPR an out of box failure. Any suggestions? I spent all day on this stupid job - should have only taken an hour!

 

Thanks in advance...

 

KE5FKP

98 Z71 SLT Senior Enthusiast

98 Z71 SLT

Posted
Posted

1. When you replace the fuel pressure regulator, it almost always comes out in pieces from the fuel rail.. Usually the top half breaks off, leaving the screen and tiny o-ring seal in the fuel rail.

 

2. I HOPE you did NOT take apart the new regulator, then install it. Because if you did, you most likely ruined it.

 

3. You still have something jammed in the rail-you said that the new FPR fits very tight--well, it shouldn't. It should have some slop when installed in the rail. I bet you still have the small o-ring seal locked in the rail?

 

4. CAREFULLY take it all apart and re-do it.

KE5FKP Enthusiast

KE5FKP

Posted
  • Author
Posted
1. When you replace the fuel pressure regulator, it almost always comes out in pieces from the fuel rail.. Usually the top half breaks off, leaving the screen and tiny o-ring seal in the fuel rail.

 

2. I HOPE you did NOT take apart the new regulator, then install it. Because if you did, you most likely ruined it.

 

3. You still have something jammed in the rail-you said that the new FPR fits very tight--well, it shouldn't. It should have some slop when installed in the rail. I bet you still have the small o-ring seal locked in the rail?

 

4. CAREFULLY take it all apart and re-do it.

 

Hey thanks for the response. When I took the bad one off, the small o-ring and fuel screen remained in the rail, as expected. I carefully removed them with a tiny screwdriver. Both were in the good condition, but I replaced them with the new ones that came with the new FPR.

 

As far as taking apart the new one, all I did was remove the o-rings (large and small) to lubricate them with clear motor oil (per instructions). The only other parts were the new fuel screen, and the plastic "back-up" ring - which I did not remove. That's all - the FPR itself is one brass piece that will not disassemble.

 

Perhaps there is some debris or foreign matter in the rail - although I would think the truck would run poorly in that case. I'll pull it back off and see if I can see anything in there.

 

Thanks again...

KE5FKP Enthusiast

KE5FKP

Posted
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Posted

Good news - truck is fixed. The FPR was in fact defective.

 

Apparently, the aftermarket parts do not work correctly. I went to the Chevy parts counter, and the design is slightly different on the OEM part. It cost almost twice as much, but it works flawlessly - no vibration and the fit was better, too.

 

I took the bad one back to Auto Zone and was cheerfully refunded. The GM parts guy said he gets lots of guys like me who couldn;t get the aftermarket FPRs to work.

 

Thanks again for the help - the answer is - go genuine part on this one. It's worth it.

 

KE5FKP

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