Fuel filter - best way to relieve pressure?

StickyPocket · Post by **StickyPocket** » 08 Mar 2020, 21:17

2004 S60, gonna back it up on ramps and replace the fuel filter with a Hengst from FCP. Best way to relieve fuel pressure? Pull the relay while the engine is running?

chris11211 · Post by **chris11211** » 08 Mar 2020, 22:54

There's a schrader valve to the left or near the tank. Unscrew the dust shield, push the pin with something like a tire pressure pen and a rag, then things should be easier.

Also, get a pan below the filter, there will be quite a spill.

Post by **oragex** » 09 Mar 2020, 04:19

COLD engine. If you do this on a warm engine, the warm fuel will keep 'expanding' and 10 seconds after releasing the pressure at the valve, when you'll pull the sensor out you will get a nice spray - warmly recommend using safety googles. When pushing on the valve, cover it with a piece of paper tower to soak the fuel and not get sprayed . Careful with the sensor screw not to strip the head, the sensor needs twisted while pulling gently and by all means use a little bit of vaseline on the o-ring of the new sensor
On a cold engine, the fuel pressure stays for weeks or months, so always release the pressure, even on a junkyard car.

Post by **abscate** » 09 Mar 2020, 04:35

You also still need to clamp off the upstream fuel hose on the filter

StickyPocket · Post by **StickyPocket** » 09 Mar 2020, 06:39

oragex wrote: ↑09 Mar 2020, 04:19 COLD engine. If you do this on a warm engine, the warm fuel will keep 'expanding' and 10 seconds after releasing the pressure at the valve, when you'll pull the sensor out you will get a nice spray - warmly recommend using safety googles. When pushing on the valve, cover it with a piece of paper tower to soak the fuel and not get sprayed . Careful with the sensor screw not to strip the head, the sensor needs twisted while pulling gently and by all means use a little bit of vaseline on the o-ring of the new sensor
On a cold engine, the fuel pressure stays for weeks or months, so always release the pressure, even on a junkyard car.

What sensor screw are you talking about? I wasn't planning on replacing a sensor. Also, am i just opening the shraeder valve? (Where exactly is it?) Am i also pulling the pump relay? I'm reading multiple how-tos and they all seem to have different ways of releasing pressure, and some of them dont at all.

Thanks!

Post by **oragex** » 09 Mar 2020, 08:54

Oh, I presumed you are replacing the FPS sensor.. my mistake. No need for fuel pump relay, just undo the small cap of the valve at the rail, cover with a piece of paper towel - it will protect you and also suck in all the fuel, and depress with something the small pin on the valve. The gas is very hard to clean off hands, and also very smelly - would only do this outside

And this is what happens when working on a warm engine - I had released the valve pressure shortly before this, but since the engine was warm, the gas kept expanding and building pressure - so always work on a cold engine

chris11211 · Post by **chris11211** » 09 Mar 2020, 10:10

StickyPocket wrote: ↑09 Mar 2020, 06:39
What sensor screw are you talking about? I wasn't planning on replacing a sensor. Also, am i just opening the shraeder valve? (Where exactly is it?) Am i also pulling the pump relay? I'm reading multiple how-tos and they all seem to have different ways of releasing pressure, and some of them dont at all.

Thanks!

The valves are, for example, what are on the wheels when you need to put in air into the tires. The part that sticks out and you have to push a pin in to let air in/out. It's the same idea for the gas line. So if you want to release pressure before releasing the fuel filter, then there is a valve between the gas tank and the filter.

chris11211 · Post by **chris11211** » 09 Mar 2020, 10:11

chris11211 wrote: ↑09 Mar 2020, 10:10
StickyPocket wrote: ↑09 Mar 2020, 06:39
What sensor screw are you talking about? I wasn't planning on replacing a sensor. Also, am i just opening the shraeder valve? (Where exactly is it?) Am i also pulling the pump relay? I'm reading multiple how-tos and they all seem to have different ways of releasing pressure, and some of them dont at all.

Thanks!
The valves are, for example, what are on the wheels when you need to put in air into the tires. The part that sticks out and you have to push a pin in to let air in/out. It's the same idea for the gas line. So if you want to release pressure before releasing the fuel filter, then there is a valve between the gas tank and the filter.

That's just how i did it, no need to open the hood, or go anywhere else.

StickyPocket · Post by **StickyPocket** » 11 Mar 2020, 10:59

Replaced it today. Pushed on the Shraeder valve and only a bit of gas dribbled out. Most of the spilling came from the open lines and old filter - but no pressurized spraying.

Post by **oragex** » 11 Mar 2020, 11:17

There should have been some pressure and hissing sound at the valve, I believe when the small stem is depressed. Will leak only little gas indeed, but must have some pressure to it