My 94 850 with 140,000 mil has error code 315 - EVAP emission control system fault which sets check engine light on.I am trying to check solenoid valve for purge control. What is the bast way to test it? If I disconect vaccum line from solenoid to intake manifod when the engine is cold and suck the air thru, should the solenoid be close or open? Any other areas I should chesk?

Thanks, Joe

joe if you have never had the evap valve replaced on your 94 850, you should just replace it. we have have many problems with evap valves, even on the later model cars. the new one is a kit with a new valve,hose and wiring connector. easy to install. i had to replace it on my 94 850 turbo. when we get one in the shop with the 315 code. we check the hoses from the evap valve and cannistor. if they are ok and the valve looks original we replace it. never had one come back with the same problem.

Where is the best place to buy evap valve and how much does it cost?

Joe,

Joe here's what the shop manual says:

Mike


Code 3-1-5 (EVAP System)
1) Check for other codes. If Code 5-4-1 is also present,
check that code first. If Code 5-4-1 is not present, go to next step.

2) Start and run engine at idle. Remove vacuum hose between
EVAP valve and intake manifold. If vacuum is present in hose, go to
next step. If vacuum is not present in hose, check for obstruction.
Also check hose connection to intake manifold.

3) Start and run engine at idle. Connect hose between EVAP
valve and intake manifold to EVAP valve. Remove hose between EVAP
valve and canister from EVAP valve. If there is no vacuum in EVAP
valve when valve is not activated, go to next step. If there is
vacuum, retest using new EVAP valve.

4) Start and run engine at idle. Disconnect hose between EVAP
valve and canister at EVAP valve. Check if there is vacuum in EVAP
valve when valve is activated. If there is vacuum, go to next step. If
there is no vacuum, retest using new EVAP valve.

5) Start and run engine at idle. Connect vacuum hose between
EVAP valve and canister to EVAP valve. Remove vacuum hose between EVAP
valve and canister from canister. Check if there is vacuum in hose
when EVAP valve is activated. If there is vacuum, check if all
canister inlets and outlets are okay. Repair as necessary. If inlets
and outlets are okay, fault is intermittent. Go to next step. If no
vacuum is present, check for obstruction in hose between EVAP valve
and canister.

6) Check hose between EVAP valve and intake manifold, and
between EVAP valve and canister for an obstruction. Check canister
connections to ensure they are not clogged. Check EVAP valve for dirt
or deposits. Repair as necessary. If no faults can be found, test
system using new EVAP valve.