2000 blazer poping multiple codes

MADMAN

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2000 blazer, 132K, 4.3 v-6, auto, 4dr., 4 wheel drive. this is driving me buggy! if one code, maybe i could fiquer it out, but as a tinkerer, i'm not a mechanic, but i've played arround a little, i reize that there might be a reason when code P0453 poped, then with it a P0452, another P0453, then a P0446, again a P0453 (pending) with a P1441. any help on were to check 1st? i believe its in the emmisions for high tank pressure, low tank pressure, but not sure with the P0446 and P1441? is there somthing causing all these to pop? thanks
 

kev2

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DTC P0452 Fuel Tank Pressure Sensor Circuit Low
DTC P0453 Fuel Tank Pressure Sensor Circuit High
DTC P0443 Evaporative Emission (EVAP) Purge Solenoid Control Circuit
DTC P0446 Evaporative Emission (EVAP) Vent System Perf
DTC P1441 Evaporative Emission (EVAP) System Flow During Non-Purge

As you see all are EVAP and this appeared all at once? - do anything repairs, maintance, off roading, wiring, accident... there is something in common thinkiig that you may not connect the codes with "something' that happened....

While you respond ....have you tried resetting and then tell what codes reapear?
 

kev2

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also I would look at the purge solenoid... purge when not commanded and no purge when commanded..
A scan tool would really help as we could command vent. purge and read FTPsensor voltage...
 

MADMAN

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nothing but normal driving, i did clear codes, 1st time driving car approx 3 miles nothing. stioped, shut off engine 20 min. resatred it and there was P0453, drove it home 3 miles, and check codes again, P0453, P0452, and pending P0453. cleared them again, had to leave for work, nothing, on the way home 10 hours later, about 2 blocks poped the mil. got home 10 miles, had code P0453, P0452, P0446, P0453 pending, P1441. try changing gas cap to original one (one on car is a stant locking cap, been on car for about a year with no problems), clear codes, drove next day, after ist start up, same codes. so i dont think its the cap. 2 years ago had to change fuel module (bad pump) but everything was soldered, and heat shrink, and taped to cut down on corrosion. just dont know how to check the purge solinoid, (if thats the one on engine) or the vent thingy (up behind spare tire)? can any of these cause that? and can the be checked in any way before just swapin parts?. did a quick visual on hoses, and electrical but everything looks good? only one vacum line running from engine mounted purge valve(?) has a vacum line (rubber) running over to left front fender, looks a little old and spongy, but seems to run into inner fender and i have no idea where it goes behind there? i dont want to start pulling on it in cas it falls apart and i have to remove fender to fix / or at least get at it. any suggestions. thanks
 

MADMAN

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FTP??? is that fuel tank pressue voltage. i'm using a little inova code reader. one bought from the neighboorhood w-mart. not really a mechanics choice, but its all i have. thanks
 

NickD

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Fuel tank pressure sensor, measures in inches of water, seldom goes bad, except for corroded connections exposed to road salt. A part of the game when the PCM decides to do an evap test that basically checks for super sub minor air leaks. Even with fuel evap codes, don't get he slightest gas odor in my air tight garage, but certainly an annoyance when your check engine lamp pops on all the time.

Placing the cannister and the vent valve at the rear of the vehicle sure didn't help matters when also exposed to road debris. Vent valve is normally opened, has to be with the ignition turned off, otherwise your seal gas tank would explode when the heat of the sun hits it. If vents through that carbon filled canister. But during the PCM test, has to be closed tighter than a drum or will kick out an error code. Can be tested with a 12 V power source and a hand held vacuum pump. Find these thing loaded with road debris and charcoal, a good rinse with denatured alcohol generally takes care of that. When closed, has to show 20"/Hg indefinitely.

Purge valve is normally closed, just the opposite of the vent valve, again has to show 20"/Hg in the normal state. Its function is to purge that canister mounted way at the rear while the engine is running, so you are burning that gas. But that canister having reverse flow through it acts like a large vacuum cleaner sweeping up road debris, more problems.

Can also find minor leaks in your fuel filler tube, yeah, everyone says its the gas cap, should be so lucky, or in the fuel sender, or even a minor pinhole in the fuel tank.

Everyone gets fuel evap codes one time or the other, so don't feel alone. Problem areas between the front to the clear end of the vehicle, can be minor air leaks or electrical problems. Have fun.
 

Mobile Dan

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Repaired a car yesterday with several evap codes...some hungry critter had eaten the wires to the rear solenoid. Also the ride height sensor.
 

kev2

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All thise codes at once I was hoping for something that could easily tie them together without going thru the trouble trees for each code... you are on the game -purge valv on eng, vent hidden up by spare, and the tank pressure is on top of tank....
As you do not have a bidirectional scanner, got to think thru this.

SOME IDEAS
reading NickD's post .... he has a good idea and plan .... start with vent valve... as mentioned sticking not venting,key on 12v pnk wire... key off white wire is not grounded use DVOM , as that would close vent without PCM command...

try that... then the PURGE valve for leaking vac to vac line eng running...
 

jasonn20

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Usually an evap cose is a gas cap and the only other thing is some work done that damaged the plastictubing which requires a smoke machine
 

MADMAN

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thanks to all, i was hoping some one had a concrette solution. quess i'll start at rear valve. maybe i can disasseble and clean but 1st i'll try using my vacum puller, and see if it holds vacum or not, then hot wire it and see if it changes. fiquer out results and move from there. but any one know abbout this vacum line going through the right side inner fender? were and how it goes? maybe that spongy rubber is worst behind there were i cant see it. any way, vent valve in back should be open when key off, and close with key on ? and engine purge should be closed key off and open key on? hope thats right, Thanks
 

NickD

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Only thing that is electrical is the fuel pressure sensor with an silly-con diode trying to guess what's leaking depending on which valve is suppose to be opened or closed when that leak doesn't have anything to do with that particular valve, can be else where just as well. Then for a system that doesn't tolerate any leaks at all, all plastic parts with plastic hoses that snap on with plastic fasteners, wondered why I even purchased a box of tools.

Did get my heat gun out though as was doing this in the middle of winter to warm these fasteners a bit so they wouldn't break off. Just pulled everything off to my warm work bench and tested everything. Well not the pressure sensor, that meant dropping the tank, but did check the connectors. That was on my 04 Cavalier, but its major problem was rust build up on the filler tube held to the tanks with a radiator kind of hose. Dealer wanted 160 bucks for a new one, before I did that, sanded off the old one, was all good metal underneath and gave it a professional paint job. That was about two years ago. Also coated all the nipples with non-hardening Permatex for a superior seal and corrosion protections.

Kid was getting all kinds of evap codes on his 2000 Taurus, first came the gas cap, loaded with debris, cleaned that off, gasket was good and put some silicone grease on in. But when putting it back on, noticed his plastic filler pipe had a crack right up on the top. Wanted a fortune for that piece of crap as well. Taped it with #33 electrical tape with a dab of hot glue so the tape wouldn't fall off and sealed that crack with RTV, that was last year, his codes never came back. Just feel on these newer systems, working with crap, and crap it is.

Don't have a smoke machine, but a good visual inspection tells where the problems are at.
 

kev2

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not so simple as open/close with key on.... operation is controled by PCM and several conditions must be met ie eng temp, fuel level, rpm, and others

Start with the easy - as stated purge no vac leaking into tubing, then the vent being stuck, it is normally open..
Wi;; look for a routing dia of the evap vac line ....but its saturday no workie
 

MADMAN

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still no luck in finding anything ? Kev2 did you ever find a diagaph of evap routing? thanks
 
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