I was wondering how to relieve fuel pressure to change the filter. I just ordered a fuel filter and the other day I tried to releive the fuel pressure by takign out the fuel pump fuse and running the car. I let it idle for about 3 minutes and it didn't stall so I am wondering how you can release the pressure. And when replacing the fuel filter, do you have to plug the lines, and does a lot of gas come out? Thanks.

By now you've probably replaced the filter already. After doing this to the first volvo I owned, I decided to no longer replace fuel filters as preventive maintenance. They are so large, and I keep the fuel tanks pretty full on average, I figure they will give ample notice of being clogged.

The cars like yours with LH injection don't store a lot of volume under pressure, so the rags are fine for me. I suppose for ideal conditions, you'd get the tank as empty as possible, and reach under the rear seat and disconnect the pump wire while running.

What input voltage do the injectors require to open? All you have
to do is disconnect one and provide it with the appropriate voltage,
either via an external battery, or through the car's 12V battery. Do
this for a few seconds; the injector will squirt whatever fuel is
pressurizing the system out. Since the ignition won't be on, the
pumps won't be running to repressurize the system.
.
Sadly, I don't have electrical diagrams for the 240, so I can't tell
you exactly how to do this.
-b.

re: "...What input voltage do the injectors require to open?... disconnect one and provide it with ... the car's 12V battery...."

I think I remember that the fuel injectors' coils are designed for less than battery voltage (5 or 6 volts). If I'm right, then putting 12 volts through them could hurt them.

I did say that I wasn't exactly sure of how to do this, and I assumed
that the external battery might need to be of lower voltage. Sorry
for the confusion, all.
.
-b.

Hello, I was a beginner on Sunday when I posted asking for help. Here's what I can tell you. After pulling the pump fuse, the car still ran for a half an hour and I surmised that somehow, there was still a bit of flow coming through the pump and filter. After a half an hour of waiting, I gave up and
1. Disconnected the neg batter cable.
2. Removed the three bolts holding the tray and sort of let things hang by themselves.
3. Loosened up, but not removed, the clamp securing the filter.
3. Removed the incoming line. You will need a 22 mm open end wrench to hold the filter flats. Everyone cautioned me about using an adjustable. You can then get a 17 socket with ratchet on the bolt and lean on it carefully.
When you get that removed, you can take the end of the fuel line and tilt it up to keep gas from dripping all over the place. In the meantime, you can then tilt the partially attached filter down to let any remaining gas drain into a container. Keep a slew of rags handy.
4. Despite all your attempts you won't be able to keep gas from going all over the place. I'd tackle the other bolt, to get the filter off altogether. You'll need to slide the filter down the clamp a bit to enable putting a 19mm socket on the end. You will also need to hold the flats, again no adjustable, with a 27 mm open end. Both sides of the filter came off easily.
5. Since there was so much gas spilled (maybe an ounce, but that's a lot), I elected to finish the job the next nite and let the stink go away on its own.
6. Use new washers if you have them. If you don't have them, someone suggested filing/sanding them flat to eliminate any indentations from previous use. I annealed mine by bringing them into the kitchen and heating them red hot (hold them with a needle nose) and when cool, clean them up with a clean rag.

Anyway, things actually went rather well. The car took about 30 cranks overall to start. I checked for leaks and amazingly, there were none.

On my 93, there's a schrader valve right next to the fuel pump you can use to relieve pressure if there's any left after running the car while the fuse is pulled. Also, when I replaced the fuel filter, I used a woodworking clamp to pinch the line from the tank. Lastly, make sure you have new copper gaskets or do as I did and just sand them flat on some 320 grit wet/dry paper. You can't just re-use them without doing that as they will have an impression from the sealing.

I find if I want to reuse the copper, a good going over with a butane torch works wonders if you can get one. They're a cheap tool that's also good for burning the carbon off the plugs when you've been running too rich.
--
Drive it like you hate it

Taking out the fuel pump fuse would do it. you must've pulled a wrong fuse...

You can also get 2 fuel clamps, hit the rubber line directly.
Or you can wrap the rag around the area and open the line.

Taking out the fuel pump fuse would do it. you must've pulled a wrong fuse...
Wish it was so, but there seems to be no LH Fuel Injection fuse that affects the Main pump directly. They all feed the FI relay, and will thus kill the injectors too.

The labeling on the '86 fuse cover is wrong. It may have been meant for a non-USA market. As shown in the WD, it feeds a K-Jet type relay. The car runs fine with Fuse #6 out. Although Fuse #4 will kill the tank pump, the car will still run.
Or you can wrap the rag around the area and open the line.
That's what works for me.



--
Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

The pressure will go down after a little while. Less than an hour.

If your worried......let it sit until the engine has completely cooled down.

Kyle245

The pressure will go down after a little while. Less than an hour.

If your worried......let it sit until the engine has completely cooled down.

Kyle245

So the best way is just to let the car cool, grab a handful of rags and maybe a pail and just remove the filter and all that ?