So I recently purchased a 1 owner 98 S90 with 181K thats in mint condition both in & out. Drove perfect for the 1st 30 miles until I reached my exit. At the off ramp, the engine had a tendency to stall as if it were out of gas. I Pumped the throttle a tad with hopes to revive & the engine roughly / chokingly snapped out of it & continued on perfectly. Sitting at the 1st traffic light for a good minute or two, I notice a strong fuel smell coming in even with the windows open followed by the engine suddenly running rough with an urge to stall & again I pumped the throttle where the engine was a bit choked up but quickly cleared & continued on fine again. The Next light, everything was smooth as silk & no fuel smell. Both these issues are on & off or just spontaneous.

I Arrive home & I could feel a slight fuel smell near the fuel filler & somewhat underneath around the LR tire. Theres no fuel smell under the hood at all even while the engine runs. BTW sometimes at idle if you sit long enough, the rough running/urge to stall thing sometime comes back & feels as if the car is misfiring but it clears with a rev or by itself if you wait a few seconds.

I plugged in my scanner tool & got the P0172 code ( System too lean bank 1 ) which my understanding is the 1st O2 Sensor & P0440 ( Evap system malfunction ). I've read in so many forums regarding the purge valve, check valve, Charcoal canister & gas cap. Some say it wont interfere with performance while others report issues. Most threads talk about these codes in V70's, S70's. & 850's while not being very clear about the problem nor conclude the thread with a solution or update.

Can the purge valve itself cause the symptoms I'm experience while at the same time cause the engine burn too lean??

 

P0172: Long-term Fuel Trim -- Lower Limit.
P0440: EVAP Valve - Leakage

Without getting too much into the inner workings of EVAP systems, you should first diagnose before throwing parts in. EVAP problems are not the easiest to find and fix. I would start with the smell -- it usually it's a pretty good indication of the source of the problem.

First things first -- replace the fuel filler cap. Gasket deteriorates and EVAP system starts leaking.

2nd, open the hatch above the fuel tank. Check those hoses connected to the tank and around the filler neck. Check also the Roll-over valve. it's above the tank. Make sure it is mounted properly. Check or even better replace those hoses with new clamps.

It should not smell back there. Do those things first and report back to the forum.

 

Yeah I removed the fuel pump cover & found a hose that was deteriorated on one side so I'm assuming thats where the fumes were coming from. I hooked on a short vacuum hose from a BMW 318ti I had laying around for the meantime until I get a proper replacement, I have driven the car a bit but not long enough to know if this solved the gas fumes issues but so far ( or mentally ) it seems to of disappeared. While at it, I pulled out the fuel pun to check on the screen to see if it had any blockage & that checked out ok. I did replace the fuel filter which seemed original as so much dark murky gas flowed out + it felt heavy.

I did buy a $12 purge valve from rockauto.com which I stupidly bought the day I got read the codes, just installed & I didn't notice any improvement.

Again it's possible I may have nailed the fuel smell issue but still the continues a slight hesitation when attempting a hard rev & or a spontaneous misfire while at idle for a few second. I did replace the spark plugs with some single prong Denso Platinums which didn't seem to help, IDK if not being the stock tri-prong plugs would help as the car does drive perfectly most of the time.. The car does continue to choke up at times when 1st engaging into drive & take off after a cold or warm start up almost as if the car were running out of gas but it always recuperates after some throttle input. Inspected the MAFS sensor which looked squeaky clean.

I've driven about 40 miles after doing all this & the weird part is that I haven't picked up any fault codes yet. I'm still quite stumped

 

You had smell and hesitation. And EVAP codes. Pretty good indication you had problems with fuel delivery and EVAP. But, you seem to be rushing, which may be justified. Yet you really need to be methodical. Fuel, EVAP, Ignition problems are not easy to find and fix.

I brought up the fuel filler cap, rollover valve, clamps and hoses. You addressed only 1 of the 4 items. What about the other 3?

Yet you go into something we didn't tell you to do -- fuel pump. There was a reason why we didnt' tell you to open the pump. Now that you opened it, you really need to go back, re-open, change the gasket and make sure new gasket is seated correctly. FCP sells it for $ 12.

Tune-up if not done already -- You should really bring the car to Stage 0, which is basic, OEM basic. But lets go over the basics (after you dealt with above):

1- Spark plugs -- Volvo OEM or plain copper work fine.

2- You should replace air filter.

3- Clean the IAC (Idle Air Control) Valve, with carburetor cleaner.

4- Clean the MAF again, with Simple Green.

5- Clean the Throttle Body with carburetor cleaner.

6- Check vacuum hoses in the engine compartment for looseness or breakage. Actually make sure vacuum lines go where there's supposed to. You would be surprised how many times people or mechanics mix them up. Follow the Diagram under the hood, or linked at the top of the Forum (resources).

- Scan for codes again.

I wouldn't do less or more than what listed here.