Hi all,

Discovery 96 (V8, 4.0L)

do I need to despressurise the fuel system before removing the black cap on the fuel pressure test port and pluging the fuel pressure tester?

Thanks a lot,

 

should be ok. The valve works like a tire valve. Might get a little spray while hooking it up, but not much....

 

That cap is only a protector. That valve is a Schrader valve and you need to press on the middle to get anything to come out.

 

Let the trk sit for 30 min and there wont be any PSI left.

 

If there is no pressure left after 30 minutes, you have a bad pressure relief valve on the pump and the pump will need to be replaced.
The fuel should stay presurized for a couple of days or else you will have lots of hard start issues.

 

The fuel pump kicks on as soon as you turn on the key to pressurize the fuel system, it is meant to lose PSI. I have never had a car hold PSI for more than a hour, even a brand new one.

 

I have opened up and bled off fuel pressure on Rovers that have been sitting for days, when the valve is working properly.
Go bleed yours off tonight and then see how long it takes for your truck to start from a cold start in the morning.

 

And waste gas? At $4.50 a gallon? No thanks.

 

since it is a Schrader-type valve I guess it don't matter if there is pressure left in the fuel system

I can just go and plug the Gauge without worry

thanks all

 

If a fuel injection system stays pressurized for a couple days, you have an exceptional fuel system and you should count your lucky stars. If a fuel injection system bleeds down after 1 hour, you have a perfectly functioning system.

The systemprimes itself within seconds of turning on the ignition key. Shouldn't effect cold start conditions.