Check Engine Light Problem

[rockinron142885]

On my 2000 Ranger, I clear all the OBD computer codes with my scanner and I am able to drive for many miles with no check engine light. However, when I turn the truck off and right back on, the check engine appears. Can anyone suggest how to solve this?

 

[MONMIX]

what code is it?

 

[koda2000]

Can't help you w/out knowing the code(s).

 

[rockinron142885]

what code is it?

evap purge valve

what code is it?

evap purge valve

 

[rockinron142885]

but the puzzling part is why does the light stay off until i turn off and then back on truck

 

[koda2000]

but the puzzling part is why does the light stay off until i turn off and then back on truck

I believe the way the evap purge valve works is that it's supposed to remain closed when the engine is turned off and open when the engine is running. That way gas fumes are captured and stored when the engine isn't running, then sucked in and burned when the engine is started. You didn't give the actual evap system error code you're getting, but there are few area's that need to be checked...

The hose leading from the fuel tank to the evap canister located over the spare tire.
The evap canister and it's mounting bracket, which tends to rust away.
The solenoid(s) and wiring at the evap canister (I think there are 2).
The hose/line going from the evap canister to the engine compartment.
The evap purge valve, which is located under the battery tray.
The hose going from the purge valve to the engine's intake manifold.

Tip: Wear gloves when touching the evap purge valve hose as it rots and will turn you hands black and is really hard to get it off your hands.