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Old 08-24-2006, 11:41 PM   #1
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Default Fuel Pressure Test...fun at Bonnevilla

While at Bill'* today replacing the HB (the correct one) I decided to check my fuel pressure to see where I stand. He wanted me to post the numbers so this is what we found:

While pressurized and sitting with the car off I held 40psi. After a few minutes it dropped to 30.

Started her up...54psi while idling.

Disconnected FPR, went up to 60psi.

While driving, held 54, under hard acceleration it went down a bit then started to creep back up. Never went below 50.

I was happy to see I had good pressure, though I never had reason to believe I had a problem or ever felt I was lacking power. Mr. Boost was surprised, and thought I may have an FPR issue.

I'll let Bill post his thoughts.
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Old 08-24-2006, 11:43 PM   #2
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sounds just like my car. Never disconnected the FPR though.
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Old 08-24-2006, 11:48 PM   #3
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Pete, I just spoke to Bill about this on the phone. I suspect you have a restriction in the return line to the fuel tank, causing a false high pressure. It could also be caused by a faulty FPR.

This could cost you in fuel economy in the long run if your PCM can't lower the duty cycle of the injectors to compensate. Another victim will be your Catalytic Converter over time. (assuming the PCM/injectors can't compensate).

Assuming the PCM and injectors CAN compensate for the higher pressure, your fuel atomization will benefit, increasing performance and efficiency.
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Old 08-25-2006, 12:00 AM   #4
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Quote:
Originally Posted by willwren
Pete, I just spoke to Bill about this on the phone. I suspect you have a restriction in the return line to the fuel tank, causing a false high pressure. It could also be caused by a faulty FPR.

This could cost you in fuel economy in the long run if your PCM can't lower the duty cycle of the injectors to compensate. Another victim will be your Catalytic Converter over time. (assuming the PCM/injectors can't compensate).

Assuming the PCM and injectors CAN compensate for the higher pressure, your fuel atomization will benefit, increasing performance and efficiency.
The first thing he asked me after we were cruising around with 54psi, "Sooo, um....how'* your gas mileage?"

Funny thing is, my gas mileage has never been better than it has been the past couple weeks. I usually got ~26mpg city and highway on a full tank. Last week on my 300 mile highway trip home from NY I got 34mpg (with a bad HB too...lol). I let the tank go down to almost nothing and averaged 29 mpg. Granted, I have a fairly light foot 90% of the time.

I asked Bill if it was a problem that my FPR could be a little faulty...if poor gas mileage is the worst thing I'm not too worried since I am fine in that regard. And the car has always seemed to run very well. Acceleration is very strong.
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Old 08-25-2006, 12:05 AM   #5
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Strong....like his right foot...lol

Funny thing Pete.. Bill says.. his pressure is jacked on the 93 at the track etc. He'* no where near ya...lol
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Old 08-25-2006, 12:12 AM   #6
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so that fruggin FPR didnt work for u bill lol
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Old 08-25-2006, 12:13 AM   #7
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Quote:
Originally Posted by BillBoost37
Strong....like his right foot...lol

Funny thing Pete.. Bill says.. his pressure is jacked on the 93 at the track etc. He'* no where near ya...lol
That'* what I was wondering. Damn I didn't think mine was THAT high.

It seems like the PCM is compensating though.

How could I check for a restriction in the return line? OR should I just replace the fuel filter as normal maintenance as check the pressure again?
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Old 08-25-2006, 01:39 AM   #8
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Fuel filter is on the SUPPLY line. Not the return line. You need to get under the car and check the return line from the fuel rail all the way back to the tank. Both lines run side by side. Look for visible bends and kinks. Assuming you don't find one, you'll be dealing with an internal restriction (line, pump, or connection), or the pump assembly or FPR.
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Old 08-25-2006, 01:51 AM   #9
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wow that pressure is a bit high.... 41-47 PSI is the range you should be in...

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Old 08-25-2006, 08:01 AM   #10
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Originally Posted by jr's3800
wow that pressure is a bit high.... 41-47 PSI is the range you should be in...
We hooked up.. I looked at the gauge and

I even hooked the gauge up to a known car to double check it hadn't gone wonky.
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