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1999 Buick Century EVAP issue.

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Aug 19, 2009, 9:18 AM

Post #1 of 4 (7536 views)
1999 Buick Century EVAP issue. Sign In

Hi, as far as you can tell i'm pretty new here. But hopefully I can get some help here because I cannot anywhere else. I have a 99 Buick Century Custom, 3.1L and cannot get the thing to pass emission inspection. My MIL light is on and for a while when I would read the codes I would get just P1441 "EVAP System Flow during non purge". I went and checked everything out from loose hoses to silenoids, malfunctioning valves, to leaking hoses, even replaced the gas cap twice and could not find anything wrong. Tonight I decided to take another look and found there is an open hose leading from a vent from the top of my fuel tank. This vent is slightly to the right of the fuel sending unit. Anyone know where this hose is supposed to go? Because I could not find any other open counterparts that it would belong to, or is it supposed to be open like that? Another thing I noticed tonight was when I checked the codes again I got another P0401 "EGR Flow Insufficient" could this be an underlying cause as to why the first code was given, because that one never came up until now, the only thing I can think of that would cause an EVAP error and EGR error would be a vacuum leak, is that right? The EVAP one has been reading for over a year. Or is it something else completely? Any help would be most appreciated, thank you.

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(This post was edited by Hammer Time on Aug 19, 2009, 10:38 AM)

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Sidom profile image

Aug 19, 2009, 5:16 PM

Post #2 of 4 (7511 views)
Re: 1999 Buick Century EVAP issue. [In reply to] Sign In

Evap codes are hard to track down with out the right equipment. For this problem you are going to need a Tech II. You are trying to fix a leak problem by changing gas caps & checking for loose hoses.. Those problems will give you a P0440, large leak or P0442 small leak. you have a P1441 which means it's purging when it shouldn't be, not a leak problem. Could be a bad purge valve, misrouted vacuum lines or an electrical problem, this is where the Tech II comes in to confirm the problem....

The EGR flow problem is a little easier to find but considering the EVAP problem, it might be better to just bite the bullet & take it in and get it diag'd


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Aug 20, 2009, 8:35 AM

Post #3 of 4 (7504 views)
Re: 1999 Buick Century EVAP issue. [In reply to] Sign In

Ok, thank you very much for the reply. I took another look at it last night and found a small crack in a vacuum line leading from my PCV valve to the intake. Before patching it and running a vacuum test it was reading just over 10hg then after i repaired the line it was reading slightly over 15, not sure if that affected anything. I wont know for a while because i cleared the DTCs and last time I did that it took forever for all the monitors to read, even after driving over 200 highway miles.

Loren Champlain Sr
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Aug 20, 2009, 1:49 PM

Post #4 of 4 (7496 views)
Re: 1999 Buick Century EVAP issue. [In reply to] Sign In

anorwood; Don't want to burst your balloon, but the vacuum leak probably won't help your initial problem. Unsure
Usually, on these engines, when we get 'insufficient EGR' (assuming the sensor and valve are okay) it is the passageway between the Throttle Body and the EGR has become restricted and requires physical cleaning. It's remotely possible that the PCV hose leaking lowered the manifold vacuum enough that the EGR hasn't been opening and caused the passageway to plug, over time. Just a wild possibility.
SW Washington

1999 Buick Century EVAP issue.

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