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Fuel Pressure Numbers

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Old 07-14-2018, 01:54 PM
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belairbrian
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Default Fuel Pressure Numbers

92 LTI, with Bosch IIIs.
Just installed a new Delphi with Strainer, removed pulsator. New GM fuel Filter.

After 5 ignition cycles 22 psi but it holds steady for a half hour.

Running is 38 (so slightly below what the FSM calls for). 56 with FPR disconnected No fuel in vacuum fitting.

As soon as you turn car off drops back to 22 psi and hold. Eventually drops to 10 after about 2 hours.

Little bit of a stumble at idle, hot days in traffic.

Is it time to replace the regulator?
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Old 07-14-2018, 04:21 PM
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C409
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….. Engine off fuel pressure will have ZERO affect on hot engine idle …..
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Old 07-14-2018, 09:08 PM
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pcolt94
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Originally Posted by belairbrian View Post
92 LTI, with Bosch IIIs.
Just installed a new Delphi with Strainer, removed pulsator. New GM fuel Filter.

After 5 ignition cycles 22 psi but it holds steady for a half hour.

Running is 38 (so slightly below what the FSM calls for). 56 with FPR disconnected No fuel in vacuum fitting.

As soon as you turn car off drops back to 22 psi and hold. Eventually drops to 10 after about 2 hours.

Little bit of a stumble at idle, hot days in traffic.

Is it time to replace the regulator?
36 to 38 is fine when idling.

56 is high with the vacuum line disconnected.
Either the pump is putting out to much pressure or there is a restriction back to the tank for the return flow

With the vacuum line connected and you rev the engine half throttle for a second the pressure should jump to about 40. If you are much higher than this there might be too much instant pressure for the injectors hence making it to rich causing a stumble. Just a theory
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Old 07-17-2018, 01:59 AM
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Hey guys new here and new vet owner got a 92 Iím having problems Iím getting around 34 pounds pressure starts and runs for a while heats up and dies not sure have replaced fuel filter and regulator not sure what next thinking injectors the ones in it the resistance on them is all Iíve from 11.93 to 12.21 any ideas ??
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Old 07-17-2018, 08:07 AM
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aklim
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Originally Posted by Batman35 View Post
Hey guys new here and new vet owner got a 92 Iím having problems Iím getting around 34 pounds pressure starts and runs for a while heats up and dies not sure have replaced fuel filter and regulator not sure what next thinking injectors the ones in it the resistance on them is all Iíve from 11.93 to 12.21 any ideas ??
I would turn the car to run and see what the pressure spikes to. See if it holds. Tape the gauge to the glass and do a WOT run and see if it holds pressure.

As to the injectors, if they are Multec, dump them. With ethanol, it could be an issue since the coil windings and ethanol don't get along and you will be forced to go to gas stations that have 93 octane 100% gas which will be a PITA.


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