Fuel Pressure Regulator.....Bad? - CamaroZ28.Com Message Board


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Old 09-10-2011, 03:48 PM   #1
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Fuel Pressure Regulator.....Bad?

Replaced the fuel pump and my car still takes a few seconds to fire up.It use to start right after I turned the key. I removed the vacuum line from the regulator and I smelled a faint odor of gas. Is that normal? I'm thinking the diaphragm may be bad.Thanks
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Old 09-10-2011, 05:27 PM   #2
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Re: Fuel Pressure Regulator.....Bad?

no, its not normal. Smell your dipstick and see if it smells of gas too. When fpr's are leaking, they leak into the manifold while its shut off and causes a flooding situation which causes the hard starts. Pressing in on the throttle while cranking it puts it into flood clear mode, which should make it start easier.

You wanna check your oil so you don't ruin any bearings from fuel contamination.
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Old 09-10-2011, 11:27 PM   #3
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Re: Fuel Pressure Regulator.....Bad?

Short answer, yes, your diaphragm is bad. You need a new regulator.
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Old 09-11-2011, 01:00 PM   #4
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Re: Fuel Pressure Regulator.....Bad?

Anyone know the torx size for the bolt that holds the two fuel lines together? I know the bolt for the regulator is a T27.

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Old 09-11-2011, 04:11 PM   #5
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Re: Fuel Pressure Regulator.....Bad?

If its only a "faint odor" I wouldn't be so sure its a faulty regulator. Wet fuel would be a dead giveaway.

They certainly didn't do anyone a favor by having the head of the screw on that bracket facing downwards. It's so long since I took that apart (and I no longer have the stock lines) that I can't remember the size. I do remember the T27 for the screw that holds the regulator on.
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Old 09-13-2011, 12:08 PM   #6
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Re: Fuel Pressure Regulator.....Bad?

All the torx on the fuel rail are the same size.
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Old 09-13-2011, 07:10 PM   #7
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Re: Fuel Pressure Regulator.....Bad?

I'm not sure what the heck is going on now.Car will fire right up after sitting all night,but now it's hard to start throughout the day. I've actually had to pump the gas a few times to get it to fire up.The car runs strong after it starts.I'm not sure when I replaced the fuel filter,but would that cause this problem? Anymore thoughts?

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Old 09-14-2011, 09:42 AM   #8
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Re: Fuel Pressure Regulator.....Bad?

Hard starting is usually low/no fuel pressure related causing 1- no fuel during cranking or 2- engine flooding. To isolate.. Get a FP gauge and verify pressure prior to starting, if no pressure then fuel is leaking either back to the tank or into the intake. Click key off-to-on 3 times to run the FP 2-3 seconds each time, and rail pressure should build and hold at high 30's to low 40's (PS: it should hold there for at least half an hour or more). After pressurizing the rails try to start it , if it kicks over fine w/o touching the throttle then low pressure was caused by fuel leaking back into the tank (open check valve in FP, or regulator fuel bypass stuck open). If it requires throttle depressed to start then as FEENIX said in post #2 , it may be flooded and low pressure is due fuel leaking into the intake caused by an injector stuck open or from a defective regulator diaphragm passing fuel through the vacuum line. .

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Old 09-14-2011, 11:57 AM   #9
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Re: Fuel Pressure Regulator.....Bad?

I replaced the pump and regulator the other day. When I checked the rail pressure after the pump install it was around the 38-40 psi mark Ill check again later today.
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Old 09-14-2011, 05:14 PM   #10
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Re: Fuel Pressure Regulator.....Bad?

Did a pressure test and during pump prime>40psi then it drops to 0. I keep hearing a noise that sound like air rushing through a tube that I haven't noticed before underneath the hood,going to try and track that down. I unhooked the vacuum to the FPR and it jumped to 40 psi from 30psi at idle. Maybe a bad(new) FPR? I also am wondering if maybe one of the hoses has somehow come off the pump in the tank.Would that cause it?

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Old 09-14-2011, 07:25 PM   #11
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Re: Fuel Pressure Regulator.....Bad?

First, 30 psi is really low. Second, the pressure is supposed to jump when you remove the vacuum hose; you are simulating WOT.
My vote would be a line came loose in the tank.
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Old 09-14-2011, 07:43 PM   #12
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Re: Fuel Pressure Regulator.....Bad?

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Originally Posted by koolaid_kid View Post
First, 30 psi is really low. Second, the pressure is supposed to jump when you remove the vacuum hose; you are simulating WOT.
My vote would be a line came loose in the tank.
I'm hoping that it's a hose in the tank.Since I did the trap door mod,it's not a big deal to get to. The pressure doesn't gradually drop from 40 to 0,as soon as the pump stops, it's on 0. Last week I was at 38-40 at idle.Maybe Ill get lucky.
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Old 09-14-2011, 07:56 PM   #13
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Re: Fuel Pressure Regulator.....Bad?

Yeah definitely sounds like a line in the tank is leaking. I had a check ball sticking that did that as well. Just an idea, though my guess would be a line leaking.

Last edited by Feenix; 09-14-2011 at 11:57 PM.
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Old 09-14-2011, 11:12 PM   #14
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Re: Fuel Pressure Regulator.....Bad?

Jumped the wire under the hood to see if I could hear anything and I did hear what sounded like gas gushing through the fuel lines and it sounded louder at the FPR.Should I be hearing anything at all?
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Old 09-14-2011, 11:35 PM   #15
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Re: Fuel Pressure Regulator.....Bad?

yeah you'll hear the fuel in the lines when you jump the pump. If it's still dropping pressure to 0 when you shut it off, I'd check the line to see if its leaking, and if the injectors are leaking if you've not done so.

The sound of the fuel rushing in the lines is normal though.
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