New fuel pump/EVAP Monitor wont complete

Backwoods16

Original poster
Member
Aug 14, 2012
21
Hey guys,

Changed my fuel pump out this past weekend, 2007 Envoy Denali, my sending unit was broke and with 100k+ miles I just replaced the entire pump/sending unit. I am due for inspection at the end of the month and would fail with the check engine light from the bad sending unit.

Have about 200 miles/ half tank of gas/more than 5 drive cycles on it so far, the check engine light is gone and there are no pending codes. All of my monitors are reading ready/complete with the exception being the EVAP monitor.

Is there a specific drive cycle that needs to be complete for this monitor to complete? Any other ideas, I wont pass inspection without this monitor reading complete. Not sure what else I need to do. Filled up after the new pump went in, currently at half a tank.

Thanks
 

McGMT

Member
Jun 17, 2012
621
Backwoods16 said:
Hey guys,

Changed my fuel pump out this past weekend, 2007 Envoy Denali, my sending unit was broke and with 100k+ miles I just replaced the entire pump/sending unit. I am due for inspection at the end of the month and would fail with the check engine light from the bad sending unit.

Have about 200 miles/ half tank of gas/more than 5 drive cycles on it so far, the check engine light is gone and there are no pending codes. All of my monitors are reading ready/complete with the exception being the EVAP monitor.

Is there a specific drive cycle that needs to be complete for this monitor to complete? Any other ideas, I wont pass inspection without this monitor reading complete. Not sure what else I need to do. Filled up after the new pump went in, currently at half a tank.

Thanks

It takes quite a few drive cycles and miles for the system to complete its checks on the EVAP system... The speed, temps, everything has to be done in a specific way and time for it to complete tests... You will be fine by the end of the month just keep on driving and it will complete the tests, I believe mine takes about 15 days with the amount of driving I do, which is alot... Just give it time and drive it as much as possible always shutting it off when you will be sitting there a while so it counts as a ignition cycle....
 

Backwoods16

Original poster
Member
Aug 14, 2012
21
Thanks, I did learn the EVAP system was the last to complete. I will check it again next week.
 

Backwoods16

Original poster
Member
Aug 14, 2012
21
Ok, the evap monitor has yet to complete. However..had the check engine come on, code P0121. It went off after 3-5 drive cycles and then it comes back on again, and then clears itself again after I drive it for a bit.

I am going to clean my throttle body this weekend and hope that clears it up, never cleaned it. Any other suggestions?
 

McGMT

Member
Jun 17, 2012
621
Backwoods16 said:
Ok, the evap monitor has yet to complete. However..had the check engine come on, code P0121. It went off after 3-5 drive cycles and then it comes back on again, and the. n clears itself again after I drive it for a bit.

I am going to clean my throttle body this weekend and hope that clears it up, never cleaned it. Any other suggestions?

Was doing some checking around and it seems that there has been some success in cleaning the TB with that code, and another instance (that I cannot confirm) where someone has cleaned the contacts on the sensor in the TB itself but I wouldn't recommend that to an inexperienced tinker...


Paging Dr. Roadie, please pick up the white courtesy phone!

Clean her up and take it out see what happens... But when you do go to clean it you need the battery disconnected and such which is going to reset your computer and you will have to wait even longer to get the EVAP tests completed. Necessary evil though, disconnecting your battery during a TB cleaning as the computer must relearn a clean TB....

Good Luck...
 

Backwoods16

Original poster
Member
Aug 14, 2012
21
Ill give it a shot and see what happens, hopefully it just needs a good cleaning and the entire throttle body doesnt need to be replaced. Given how this code comes and goes I think the cleaning will take care of it.

I am aware of disconnecting the battery prior to cleaning the TB, I am going on a fairly long trip this weekend, 800 miles roundtrip, going to try and get this cleaned prior to leaving. Hopefully the EVAP monitor will complete during the 800 miles.

Thanks for the advice.
 

Backwoods16

Original poster
Member
Aug 14, 2012
21
Update - I cleaned my throttle body and MAF sensor over the weekend. Put 600 miles on the truck since then with no P0121 code. Looks like it just needed to be cleaned, was pretty dirty. If anyone is getting a P0121 code try cleaning your throttle body and MAF before anything else. The EVAP sensor still has not completed, I am taking it in for inspection next week regardless.
 

canbust

Member
Nov 23, 2012
5
Backwoods16 said:
Update - I cleaned my throttle body and MAF sensor over the weekend. Put 600 miles on the truck since then with no P0121 code. Looks like it just needed to be cleaned, was pretty dirty. If anyone is getting a P0121 code try cleaning your throttle body and MAF before anything else. The EVAP sensor still has not completed, I am taking it in for inspection next week regardless.

Did you pass inspection without the EVAP monitor completed?

How many monitors did complete?
(I'm guessing 6)

I have the same problem - need a sticker, but waiting for EVAP.
 

91RS

Member
Dec 4, 2011
105
You don't need the EVAP test to be completed to pass an OBD inspection. As long as the check engine light isn't on and all of the other tests have run, it will pass.
 

Backwoods16

Original poster
Member
Aug 14, 2012
21
91RS said:
You don't need the EVAP test to be completed to pass an OBD inspection. As long as the check engine light isn't on and all of the other tests have run, it will pass.

Yes, this is accurate. In NJ you can have 2 systems incomplete and pass as long as the check engine isnt lit or in a pending status. I passed inspection with no problems.
 

canbust

Member
Nov 23, 2012
5
Thanks 91RS and Backwoods - you guys were correct!!

I tried again today and it passed MA inspection even with an Incomplete EVAP!

They said Chevy was slow to complete.
It took less than 200 miles to get the other 6 monitors to complete.
 

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