Monkeyboy

Looking for input on a problem with my car maintaining fuel pressure. Thought I had it licked as I changed my fuel pump this past weekend. The starting issue is improved (typical hard start on first attempt, starts fine on second attempt), but pressure is still not being held after shutting the car off.
I have a fuel pressure gauge installed.
Bleeds down to zero psi after @2 minutes - per Bentleys, it should maintain @20psi after 10 minutes.

What would cause fuel pressure to bleed off after turning the car off?

Long time problem, so here is a recap of what I have done that may be related:
- Seafoam
- All new check valves and Vac lines
- New spark plugs, gapped correctly (actually have been thru @3 different sets since the problem began)
- Had injectors electronically serviced to clean and check for any leaky injectors - no problems.
- Installed new fuel pump (stock)

Only thing I can think of next is:
1) replace fuel filter (for the heck of it - a dirty fuel filter should not cause fuel pressure loss)
2) replace fuel pressure regulator

what else might I be overlooking?

thanks

Yippers®

read Bentley's 'test procedure'

Monkeyboy

You can insert a fuel pressure gauge in the fuel line and take readings with and without the FPR line connected.

With connection: Specified value: approx. 3.5 bar (50 psi)

<b>pass</b>

- Disconnect vacuum hose (arrow) for fuel pressure regulator.

Fuel pressure must increase to approximately 4.0 bar (58 psi)
<b>pass</b>

Reconnect vacuum hose.
- Switch ignition off.
- Check for residual fuel pressure by monitoring decrease in pressure on gauge. Specified value:
After 10 minutes: at least 2.5 bar (36 psi)
<b>fail</b>

Obviously, the last portion fails since pressure drops to zero after @2minutes.

Not sure what Bentleys says to do next or where the problem may be (although you said FPR).

DAP@EPL

Does the pump have a check valve?

-Dave Pramanik

Monkeyboy

OEM - direct replacement..pump and basket..VDO/Siemens unit

2.0GT35

there will be full pressure once the key is turned to on for a few seconds before trying to crank the engine.

2.0GT35

Problem would be caused by the tank not being pressurized and allows the fuel to run down the return line back to the tank or back thru the fuel pump.

Monkeyboy

start car.
shut it off.
Clamp off the fuel line past the rail and FPR. If pressure is maintained, then the FPR is likely stuck open (outside chance of leaky injectors - since I did just get them bench cleaned/serviced).

(I assume I can just pinch the rubber fuel line with a big set of pliers)

Monkeyboy

but my car definiately fails the Bentley specs of maintaining fuel pressure of at least 20 psi after 10 minutes of shutting down. This, I believe, is the root of my hard starting problems.

Joey T

Pull the hose off the regulator and see if you smell fuel. Often, the regulator leaks, pushing fuel in to the vacuum hose, making the car run very rich when you first crank it.