 Fuel pressure, Measured while running or just key tured on? |
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| gunny |
 Nov 5 2012, 08:04 PM
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#1
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Member  Group: Members Posts: 205 Joined: 17-October 12 From: Madison Al Member No.: 15,051 Region Association: South East States  |
When do you measure the fuel pressure? I get 29 lbs when I turn on the key and 32 lbs when it's running.
1976 2.0 DJet |
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| ConeDodger |
Nov 5 2012, 08:06 PM
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#2
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Apex killer! Group: Members Posts: 23,589 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California 
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I think that's spec... You measure running.
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| Dave_Darling |
Nov 5 2012, 09:52 PM
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#3
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914 Idiot Group: Members Posts: 14,986 Joined: 9-January 03 From: Silicon Valley / Kailua-Kona Member No.: 121 Region Association: Northern California
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Measure running; 29-30 is the spec. At 32 PSI, you'll be a little richer than at spec. If that's working for you, then good enough.
--DD |
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| walterolin |
Nov 5 2012, 11:08 PM
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#4
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Senior Member Group: Members Posts: 685 Joined: 30-November 11 From: Louisville, Ky Member No.: 13,838 Region Association: South East States |
Difference is probably a function of the alternator running. Ignition on, but no alternator, you are drawing on the battery, and any load will drop the voltage a little. With the engine running you are probably getting a robust 13.5 volts into the system.
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| ConeDodger |
Nov 6 2012, 01:34 AM
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#5
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Apex killer! Group: Members Posts: 23,589 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California
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QUOTE(walterolin @ Nov 5 2012, 09:08 PM)  Difference is probably a function of the alternator running. Ignition on, but no alternator, you are drawing on the battery, and any load will drop the voltage a little. With the engine running you are probably getting a robust 13.5 volts into the system. (IMG:style_emoticons/default/blink.gif) fuel pressure Walter! Fuel pressure! (IMG:style_emoticons/default/biggrin.gif) |
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| walterolin |
Nov 6 2012, 06:59 AM
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#6
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Senior Member Group: Members Posts: 685 Joined: 30-November 11 From: Louisville, Ky Member No.: 13,838 Region Association: South East States |
I was thinking (?) fuel pump is an electrical device, subject to variations in the voltage, but forgot there is a pressure regulator in the line. On the other hand, if the regulator is a really precision device, it shouldn't matter what the pump is doing. Perhaps the fuel flow in the dynamic state causes the small drop.
Back to sleep. |
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| gunny |
Nov 6 2012, 08:21 AM
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#7
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Member Group: Members Posts: 205 Joined: 17-October 12 From: Madison Al Member No.: 15,051 Region Association: South East States |
I guess I will need to reduce to 30 while running.
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