Its possible to post pics here but I dont know how yet.

on my Volvo 122 there is a thing above the differential with three lines to it , but those are brake lines and it's a pressure accumulator I think , basically a piston with a spring behind it all sealed into a unit that never seems to fail. my van has a brake proportioing valve and it leaked and it has rear drums.. its near the reservoir.

I think the 240 doesn't need that brake accumulator as it has 4 wheel disks.

there might also be basically a brass block with 3 brake lines, it has a spool and if one side of the split braking system has fluid loss the piston shifts, a switch reacts. and turns on the brake warning light. I think that one is on the firewall or near the brake reservoir.


I'm curious what this thing is. often the canister is in some out of the way place and outside the car.. some are tucked away under a fender. I can't think where it is on my 240. I have an 89 someone will know this.. the cannister is probably about the size of a 1 lb coffee can and if that isn't in the engine bay you can probably follow the thin PVC ( not rubber) line from just past the Air mass meter to where it is.

the fuel tank makes pressure sometimes, or maybe vacuum too. so it vents through the charcoal and then the manifold vacuum pulls air from the canister. There might be more to it.. maybe also a larger line. those lines may leak and that might cause poor running because any air that can enter without the AMM seeing it will cause the injection system to not inject the fuel needed to keep the balance of air fuel mixture.

under the drivers seat there will be a fuel pump and the filter. its on a bracket with rubber mounts.. It pressurizes the fuel fed from the pump in the gas tank. sends it up to the fuel rail and there is a return line, any fuel not used is allowed to return back to the gas tank. there might be a check bvalve somewhere in that system.. ?

a fuel pump doesn't "make pressure" not exactly, because it needs fluid resistance to have pressure , the fuel rail has a pressure regulator that maintains a certain fuel pressure and I think that is adjusted by the amount of vacuum in the manifold, more vacuum , more fuel pressure. the engine sucks harder and it gets fed more fuel the rest returns to the gas tank. I think that's basically how that works. in laymens terms.
vacuum is weird though, taking your foot off the gas increases vacuum. engine is "sucking" but throttle plate is closed, that creates more negative pressureinside the manifold, I think..

I remember having an old truck with vacuum driven wipers and it would stop wiping sometimes and I'd have to lift off the gas to get them to run ,so I could see. I was increasing the vacuum by lifting off the throttle.