• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

240 B21 evaporative canister question

bwright002

Active member
Joined
Feb 12, 2005
Have a 78 242 with a manual B21(e I believe).
I've been trying to track down a rough idle from cold. I was reading a thread about idle that was referring to a link between idle, vacuum when removing the gas cap and the evaporative system.

My evap canister has a Volvo part number of 1266459, round in shape, up by the passenger side headlight with two hoses going into the top and one hose coming out the bottom. One of the hoses (the smaller diameter of the two) was a loose fit on the canister, so I've replaced it with fresh hose that is a tight fit. The other end goes onto a plastic tubing line.

Replacing the hose has given me a smoother idle (at 900-950 rpm), so that's good news, but I'm still hearing a major suction when I release the red Volvo gas cap (has the four holes in the underside of the gas cap). And the car will make a surging or pulsing noise if I run it much below 1/3 tank.

The hose that comes out the bottom doesn't connect to anything. Is that correct? The canister already has a vent hole in the bottom, so I'm wondering why the bottom hose isn't connected to something.

I've looked in my Bentley's as well as the Haynes manual for the pre-80 240's. Not finding any details about the bottom hose.

Car runs great, so I don't think there's anything seriously amiss, but a hose that goes nowhere has me wondering.

78 242 180,000 mi, 4 speed.
 
You have the early charcoal canister setup. A hose that is plastic should be coming from the back of the car. If I recall it's from the filler neck on the gas tank. The other hose should go to the throttle body to use vacuum to burn the fumes. The bottom hose on the canister is a drain for condensation that gets in there.

Common idle issue is injector oring seals. If your seals are older than three to five years old. They need to be replaced just for proactive maintenance reasons. A vacuum leak on the intake manifold from a bad gasket or a badly installed intake boot on the throttle body can all cause vacuum leaks affecting the idle. Don't forget to check over the pcv system. That can also make a vacuum leak.
 
Common idle issue is injector oring seals. If your seals are older than three to five years old. They need to be replaced just for proactive maintenance reasons. Don't forget to check over the pcv system. That can also make a vacuum leak.

I owned this car for 10 years until Bruce bought it, and it always had an inconsistent idle when warmed up. I did all the flame trap parts and vacuum lines in 2010, and I replaced the injector o-rings probably 5-7 years ago, chasing idle issues. It didn't make a difference, but that's all probably about due anyway,

This car also had a loud fuel pump noise that would pop up in hot weather with low fuel in the tank. It ran no differently, but never did it at idle long enough for me to open the gas cap to check for suction. In the end, I thought it may have been vacuum building in the tank due to clogged vent hose, but never got around to checking that out. The in-tank pump works and has a new hose.
 
There should be some kind of valve to control when vapors are drawn from the charcoal canister. Some are inline (34,42) and some are right on the canister (9). The valve only allows vapors to be drawn from the canister when the throttle is open. If the valve is missing or damaged it may be drawing vapors all the time causing lower than normal vacuum to lift the air flow meter plate at idle.

GR-22016.jpg
 
Thanks Stephen for the background on your time with "Casey" (the yellow 242) and thanks to HiPerfAuto for the exploded diagrams.
My canister is the bottom left illustration and the hoses 20, 21, 29 and 27 are in place. Not sure why there's a 28 connected to the 27 hose if that's just a drain hose for condensation.

So I guess my next task is to make sure that I have a #42 valve and if so, make sure it's functioning correctly. I'm assuming that this valve is somewhere back near the gas tank, but I'll check my Haynes and Bentley manuals next.

If this is still the original canister, would it still be functioning correctly. I'm assuming it has activated charcoal or some such material inside to absorb the vapors.

And in regards to the gas tank, I've just made it a practice to always keep it over half full so I don't get the noises (sounds a bit like an old oil can flexing) when the tank gets below half full.

But I do want to emphasize that the car runs very well and the slight irregular idle when first starting up is not affecting normal driving.
 
Back
Top