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Chevy 3.5 issues

ConwayMuddy

ConwayMuddy

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May 19, 2020
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307
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Jerkwater wi
Truck is a 2004 chevy colorado with a 3.5L. Been throwing codes, but generally running ok. Twice prior to today its done the same thing, stop for gas, get on highway and it surges, check engine light flashes, then it will pull hard without trying, light goes off, no codes. Today it did it while I slowed and made a corner, cleared up and I parked it. Scanned it with the $20 special, pending codes p0300 and p0171, random misfire all cylinders and lean bank 1 (only has 1 bank), respectively.

Codes I've found before;
P0300 misfire all cylinders : I normally assume shit gas
P0305 misfire cylinder 5 : figure due for plugs
P0455 evap system control leak : bad gas cap?
P0171 : system lean bank 1 : there is a fuckton of possibilities here.

Tried to drive to town for parts, first stop 1/4 mile away, started surging, cleaned up. Drove a bit and it got low on power and surged bad enough I limped home.

Things I have done, in order; replaced fuel filter, air filter and cracked pcv hose. Cleaned MAF sensor and throttle body. This helped for a few weeks. Then the truck truck would alternate between codes p0171 and p0455. Today I recleaned the MAF and T.B. threw new plugs in it, and swapped coils between 3 and 5. The vacuum line from the intake to fuel pressure regulator had backed off, broke it removing the intake, cobbled another together, and replaced the gas cap.

Started the truck up, surged a little then briefly ran fine. Started missing bad as it warmed up. Shut it off, pending codes p0171 and p0300. Cleared the codes, started back up fine, CEL started flashing and it started missing, sprayed everything looking for a vacuum leak, didn't find one, same pending codes.

I have an o2 sensor coming tomorrow, earliest I could get one. Fuel pump dying on me? Not really sure what else to check, or what is common.
 
First, I'm not an expert. But with the research I've just done, I'm lead to believe the code to focus on is P0171. Every site and video I looked at all state it had to do with an air leak generally, whether it's intake or exhaust. The other possibilities from what I recall are MAF sensor, O2 sensors, fuel filter, fuel pump, or injectors.

Since you've stated checked the intake track, I would look over it in more detail to make sure you haven't missed anything. I'm not saying your not being thorough, but it's possible you may have missed something. I would also to look at your exhaust manifold for any cracks along with checking the connection between the exhaust manifold and exhaust itself.

Once you're satisfied that there are no air leaks, move on to diagnosing the other items. There plenty of information out there on how to test them.

And from what I remember, O2 sensors are a wear item that should be replaced every 60,000 to 90,000 miles. Replacing them wouldn't be a bad idea.

Good luck... :beer:
 
I'd start with fuel pressure test, get a gauge with a long enough hose to stick it under the wipe to watch while driving
 
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GM's that era are pretty shit at giving a specific cylinder misfire code, without a more fully featured scan tool you won't be able to see the misfire data you need to determine if moving that coil moved your misfire or not.

A misfire will also show lean and if left long enough could give the lean code, I would figure out the misfire first before worrying about the lean code. A leaking EVAP purge valve could give you both the lean code and the EVAP code too.
 
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New o2 sensor didn't help. Swapped fuel filter after chiseling the ice off, no help. Went back through intake, coils, no difference. I hit the pedal when I had it running the second time, zero throttle response. After swapping the fuel filter and starting it, I had throttle response again.

Since the manual is less than helpful, dumb question: there is a Schrader valve on one of the fuel lines, can I hook a pressure tester to that? The manual shows the test port as the random end of a line. If I can get pictures functional I'll post what I mean
 


Port on line. I did have gas shoot out
 

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Going to get a pressure tester after work tomorrow. Looking at fuel pumps, fucking hell its all one unit, not just a pump in a sending unit.

Trying to figure out the correct one, oreilly had 2 acdelco, a Delphi, and precision. Napa had napa, Bosch, and Delco. All different, but they all claim to fit the truck.
 
I only install AcDelco or Delphi in GM stuff, they're too much work to cheap out on IMO unless you're gonna hack a hole in the bed.
 
Kinda shitty that there's options, you'll have to figure out how many wires are going into yours, seems to be the difference between them.
 
Fuel pressure should be 50+psi koeo. I get around 30. Truck running it bounces between 50ish and 60 ish















Edit, that's the engine off pressure after bleeding the gauge and one pump prime. If I cycle the pump the pressure will increase
Double edit, started again barely hits 50 psi running
 
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Are you refilling while running? Evap valve near the tank, pop the cover off, foam thing is probably dirty, rinse clean and replace.
 
ConwayMuddy said:
Twice prior to today its done the same thing, stop for gas, (hmmm, this is a clue) get on highway and it surges, check engine light flashes, (this indicates an active misfire) then it will pull hard without trying, light goes off, no codes.

P0455 evap system control leak
Click to expand...
I would start chasing the P0455 first. Verify canister purge valve and canister vent valve are both sealing when they are commanded off. I see a lot of problems with both in a pretty regular basis.
 
Thatg9659 said:
Are you refilling while running? Evap valve near the tank, pop the cover off, foam thing is probably dirty, rinse clean and replace.
Click to expand...


No, shut the truck off while filling. I don't overfill either. Evap purge valve is buried on the side of the engine, vent valve/ control solenoid is by the canister in back of truck[/QUOTE][/QUOTE]
 
Johnny Longrifle said:
I would start chasing the P0455 first. Verify canister purge valve and canister vent valve are both sealing when they are commanded off. I see a lot of problems with both in a pretty regular basis.
Click to expand...
How do I test these, manual just says where/what they are and how to replace them.
 
Started working on getting the tank dropped. Sucks working on a tarp on a soupy gravel driveway. Soaking bolts overnight. Fun fact, the front of the tank is under the cab and
over a crossmember
 
Tank is out. New pump tomorrow morning. After a bunch of reading and comparing, only thing I could find different between pumps is what they come with. Float, sending unit, seal... trying to understand the lock ring. New part shows full circle, I have this.
20230407_171828.jpg
 
TrikeKid said:
Yours was a full circle when it was new, the rest has returned to the earth with the help of your state DOT















That's what I was beginning to think. Now I'm wondering if I have a tank full of shit gas from snow and water seeping in.
Click to expand...
 
Well this got interesting. The tabs that hold the lock ring are also rotted off. Didn't notice until I pulled the sending unit. Because the sending unit is spring loaded, it won't seal. There is not enough remaining tab to try and fold it over. GM discontinued the tank, I can't find anyone that makes a new replacement. Found 2 used ones through u-pull,but what shape they are in is anyone's guess.
 
Searching I found the following:

GM 15239258 Tank kit, genuine OEM part

19.5 gallon fuel tank GM genuine OEM part.
oemcats.com oemcats.com

Supposedly three available OEM tanks with the above link. And I found there are "repair" kits for the rusted lock ring issue:

www.ebay.com

CANYON -COLORADO 2004-05 PLASTIC GAS TANK LOCK RING REPAIR #TR27-R | eBay

THAT HOLD IN THE FUEL PUMP ON 2004-05 COLORADO AND CANYON TRUCKS. CANYON -COLORADO 2004-05 PLASTIC GAS TANK LOCK RING REPAIR #TR27-R (#283936420371). COLORADO / CANYON 2004-2005. TR27-R PLASTIC TANK LOCK RING REPAIR KIT FOR 2004-2005 GMC CANYON/CHEVY COLORADO - YouTube.
www.ebay.com

That link is the actual company that makes them, Erson Inc. And a video that covers the installation process:



Hopefully one of these options will help... :beer:
 
Will Scarlet said:
Searching I found the following:

GM 15239258 Tank kit, genuine OEM part

19.5 gallon fuel tank GM genuine OEM part.
oemcats.com oemcats.com

Supposedly three available OEM tanks with the above link. And I found there are "repair" kits for the rusted lock ring issue:

www.ebay.com

CANYON -COLORADO 2004-05 PLASTIC GAS TANK LOCK RING REPAIR #TR27-R | eBay

THAT HOLD IN THE FUEL PUMP ON 2004-05 COLORADO AND CANYON TRUCKS. CANYON -COLORADO 2004-05 PLASTIC GAS TANK LOCK RING REPAIR #TR27-R (#283936420371). COLORADO / CANYON 2004-2005. TR27-R PLASTIC TANK LOCK RING REPAIR KIT FOR 2004-2005 GMC CANYON/CHEVY COLORADO - YouTube.
www.ebay.com

That link is the actual company that makes them, Erson Inc. And a video that covers the installation process:



Hopefully one of these options will help... :beer:
Click to expand...

If the tank was a third of that price, I'd order one. Thanks for the link, everything I found was discontinued and out of stock. Cut some repair rings today. Been siphoning gas. Need to figure out how to such the chunks of crap out. Boat fuel line and primer bulb don't work.
 
New pump is in. Thoughts on how to leak test it? New o ring for the sending unit fit for shit, but I think I finally got it to seat in the groove long enough to get the pump in and held down. Holes for self tappers were pre-drilled and filled with rtv before running them in tight.







Picture of this dumpster fire.
 
The video I included above had a testing section to verify it was sealed good enough. If I remember correctly, they spraied soapy water around the fix and used an air compresson to pump air int o the middle hose attachment to about 3 PSI. No soap bubbles, no leakes.

Hope this helps... :beer:
 
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