Fuel Pressure

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Apr 17, 2004 | 09:45 AM

#1 (permalink)

Alan

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drives euro trash

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Fuel Pressure

Stupid question:

Just hooked up an Autometer mechanical fuel pressure gauge to my fuel rail (used an NOS fitting instead of the Autometer which broke before...NOS has much better fit/finish). Anyways, I adjust the Kirban FPR to read 39psi without vacuum. When I put vacuum to it, it drops to 31psi. I'm assuming this is normal, right? Unfortunately I don't have an in cockpit fuel pressure gauge, so I can't see how the fuel pressure rises under boost. But Kirban is "the bomb", so I guess I'll have to trust it until I can eventually find my way to a dyno.

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Apr 17, 2004 | 10:16 AM

#2 (permalink)

Mars_302

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Yea its supposed to drop. It just varies, But 8# seems a little too much. Id ont know, mine only drops 5-6

Apr 17, 2004 | 10:16 AM

#3 (permalink)

SLO5OH

torque on tap

Joined: Apr 2003

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I believe Ford's spec is 39psi with the vacuum hose disconnected. A drop in pressure with the vacuum connected is normal.

Edit: It seems like most 2.3T guy lose between 6 and 9psi with the vacuum connected.

Last edited by SLO5OH; Apr 17, 2004 at 10:19 AM.

Apr 17, 2004 | 10:16 AM

#4 (permalink)

Just Dave

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Its working fine. Basically, the more vacuum the motor is making, the less load it is under and the less fuel pressure it needs. If it were an N/A car, no vacuum in the motor (represented by pulling the vacuum line off the FPR) represents max load and thus, max fuel pressure. Now on a turbo car, once you go past "0 vacuum" you make positive pressure, causing fuel pressure to rise above that 39psi to compensate for boost.

You're going tonight right?