Fuel pump and gauge issues

[gica]

Hello and hope to find everyone still here and in good health. I haven't done anything else to the trailblazer since last year about this time. Wanted to update on what I am doing now since this is the only venue where people still talk about this car.
So I took out the tank today and ordered the inlet valve, new AC Delco pump and lock ring. Will install tomorrow. The inlet valve was leaking and it is visible after driving as it is damp around it. I assume that will fix the P0422 code that is probably causing a somewhat lean condition. The car is heating up again it went to 128 yesterday going up a short hill at low speed. I know that's not normal because it didn't use to do that 3 to 4 years ago. So for now I am doing the tank and getting rid of the P0422 code. I am wondering if that will make a difference.

 

[gica]

By the way I bought the Tech2 VxDiag scanner and it does read the car but I cannot use it to test the fan clutch it does not trigger it and any percentages. What is the cheapest scanner you guys are using for a trailblazer that can do bi directuonal stuff?

 

[mrrsm]

This one is probably the least expensive Pro Grade OBD2 Hand-Held Scanner that has the ability to run Bi-Directional Tests along with a whole battery of other sophisticated diagnostics at roughly 1/2 the price of the Lower End Autel Pro Scanner:

https://www.amazon.com/dp/B07Z481NJM/?tag=gmtnation-20



... not sure if devices like these can Read and Write PCM Calibrations like the Tech 2 Scanners and TIS2000 SPS Software can perform. In your present situation...updating your PCM might cover a 'multitude of sins' and solve outstanding problems that GM already has solved with SW Updates.

 

[Mooseman]

The new fuel pump will do absolutely nothing for your P0422 code. Your cat is likely plugged and causing your heating issues. You would need to do a back pressure test on the exhaust to confirm. You can also use a temp gun to confirm the cat is dead as per this video:

Lack of power and overheating are also signs of a plugged cat. You can remove and unplug the upstream O2 sensor to see if engine performance and overheating improves.

The VXDiag should be able to do bi-directional. Do you have Tech2Win? It emulates the Tech2 scan tool on the computer and should be able to do everything the Tech2 does. Don't go to the extra expense of an expensive scanner just for the fan testing. As you've seen before, there are other ways to test it.

 

[gica]

Read about the 5610 scanner and under reviews a guy with a 2007 chevy avalanche said it did not perform most functions on it. So did you actually use it on a trailblazer?
I do have the a few scanners like the Autel MD802 which I like and it's 5 years old at least, and a Foxwell NT650 which is not what I expected.
I do have the VXDiag with the Tech2Win but it won't do the Fan speed test successfully. It tells me the fan speed but cannot get the fan to go at different percentages when I click on the option. Just does nothing to the fan speed, it stays the same when I input 10% , 50% or whatever. It does do the purge valve tests and it resets at 11% probably from the inlet leak. I am using it on a win7 X32 and it's pretty unstable on it I wish they made it more stable I cannot access all the screens just the main ones. Do any of you have this and run it successfully? If so how?

I know the pump replacement will not fix the P0422 but it will give piece of mind that the pump is new. The inlet valve leak should fix the P0422.

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I always wanted a bi directional scanner for home use but never justified spending the 800 plus on it. I do love these gadgets though. Have a friend that bought the Mercedes dealer system probably cloned from China for about 1k and it does everything the dealer one does on any models. I have the E350 2011 and it is great on it. Wish the Tech2 clone was as handy and precise. It was $100 so you get what you pay for.
I tested the exhaust pressure with the front(before the cat) O2 sensor removed and it stayed at 0. I did not do the temp check or the oxygen voltage yet, but I will it looks like a great way to test. As soon as I get the inlet check valve in place(coming tomorrow) and the tank back up I will test again.

 

[mrrsm]

I have a "GYMKO" (General Motor Knock Off) Full Bosch Vetronix Tech 2 Kit... so No... Other than answering your question about whether there are any "less expensive" OBD2 Scanners are out there with Bi-Directional Features ...you should be suspicious if others on the related GM Platforms caution you away from getting one.

Regarding the inability of the Fan Speed to respond may have more to do with something going sideways in the Wiring being the problem and less to do with any defect with your present Scanner.

Scannerdanner did this excellent Trailblazer Electro-Viscous Fan Diagnosis Video showing his Step By Steps while covering the topic quite completely. Ignore the fact that the specific code he is concerned with is not your issue, as the procedures he follows are the standouts worth seeing:

 

[Mooseman]

Regarding the inability of the Fan Speed to respond may have more to do with something going sideways in the Wiring being the problem and less to do with any defect with your present Scanner.

Yeah, I thought the same thing. Wiring or the EV fan clutch itself. If it's the only thing the scanner can't do, I'd suspect the clutch itself.

 

[gica]

As soon as I put the inlet valve back in I will report.

 

[gica]

Was looking at the Autel DS808. They look interesting.

 

[TJBaker57]

but it won't do the Fan speed test successfully. It tells me the fan speed but cannot get the fan to go at different percentages when I click on the option. Just does nothing to the fan speed, it stays the same when I input 10% , 50% or whatever.

At what engine rpm are you doing the elevated percentages? In my vehicle I find that at idle there is no difference, you won't notice anything. You have to hold rpms up higher like 1500 to 2000 to see or hear any real difference. And the response is very quick to ramp up but requires a minute or more at no less than 2000 rpm for the fan speed to ramp down.

 

[TJBaker57]

With regards to the catalytic converter..... do the o2 sensors provide much diagnostics on a clogged vs normal catalytic converter??

I have no issues with mine, to be clear.

Once again I like the Torque app for looking at such data. In particular for o2 sensors. Using the graphing function I find easier than watching a fluctuating number. Here are 2 screenshots, the first showing normal cruise and the second showing a change to near wide open throttle with power enrichment.

Any speculation on what would a clogged catalytic converter look like? Or would it be any different??

 

[TJBaker57]

I just reviewed the thread and noted you have already checked out the catalytic converter for blockage so we can somewhat ignore my last post directly above.

 

[Mike534x]

The new fuel pump will do absolutely nothing for your P0422 code. Your cat is likely plugged and causing your heating issues. You would need to do a back pressure test on the exhaust to confirm. You can also use a temp gun to confirm the cat is dead as per this video:

Lack of power and overheating are also signs of a plugged cat. You can remove and unplug the upstream O2 sensor to see if engine performance and overheating improves.

The VXDiag should be able to do bi-directional. Do you have Tech2Win? It emulates the Tech2 scan tool on the computer and should be able to do everything the Tech2 does. Don't go to the extra expense of an expensive scanner just for the fan testing. As you've seen before, there are other ways to test it.

OP mentioned they used an off-brand/aftermarket one. What are the chances the new cat is tripping the fault code? When I did calling around about doing a universal one in my Envoy, every single shop mentioned vehicles would come back because of a cat fault code after installing an off-brand/cheap one. With how picky GM/this platform is, seems plausible with how much these things love "OEM" parts.

 

[gica]

Pisses me off I just changed the fuel pump assembly and now the gauge shows full after restart and after awhile goes to empty, than to half back to empty. Shows full after restart. I have 7 gallons in it.
I checked the temp on the cat before is 375F⁰ after 420F⁰

 

[gica]

Here's the O2 at 2k RPM graphs and numbers.O2x1 goes back and forth O2x2 pretty stable

 

[gica]

So the gas gauge seems to have stabilized and it's sitting a bit below half with 7-8 gallons. No longer going to full or zero. Is it self adjusting?! Maybe.

 

[gica]

More Torque shots at 2k RPM
It's a hot day today in Liberal So Cal.

 

[budwich]

With regards to the catalytic converter..... do the o2 sensors provide much diagnostics on a clogged vs normal catalytic converter??

I have no issues with mine, to be clear.

Once again I like the Torque app for looking at such data. In particular for o2 sensors. Using the graphing function I find easier than watching a fluctuating number. Here are 2 screenshots, the first showing normal cruise and the second showing a change to near wide open throttle with power enrichment.

Any speculation on what would a clogged catalytic converter look like? Or would it be any different??

View attachment 95383

View attachment 95384

I would think that the "waggle" on the upstream which you are showing would be not as regular along with a different response downstream response, a slight "waggle" or possibly higher than "normal" plateau.

 

[gica]

Went back to full on the gauge. Damn it.

 

[TJBaker57]

Have you had a look at fuel level in Torque to see if it's the stepper motor in the cluster failing?

 

[gica]

I changed all the stepper motor on this dash not too long ago. And before I changed the fuel pump it worked great. Wanted to know if I should get another pump and fuel sending unit assembly? It would be weird if it was the stepper. I didn't check with Torque yet. if the Torque doesn't say otherwise, I still have to lower the tank back down and unplug the harness and plug it in the old one without putting it back in the tank and see if it works.

 

[gica]

So TorquePro is the best app for android car monitoring?
I only had the free Lite.
Does it show fuel level also?

 

[Mooseman]

Moved these recent posts from your older unrelated thread. Please create new threads for new issues.

 

[TJBaker57]

So TorquePro is the best app for android car monitoring?
I only had the free Lite.
Does it show fuel level also?

I don't think Torque shows fuel level as a default option......but you can get what you need to add that parameter manually from the thread "More Pids for Torque App" here on GMTNation. Look at post #31. You don't need to have Torque Pro for this one, the current free version will allow adding new Pids manually.

 

[TequilaWarrior]

I had similar gauge behavior and traced it down to a bad fuel pump/ sender assembly AND burnt wiring at the tank. Only after addressing both did my issue go away.