Filters arrived, have to go back under the TB

movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
Like I have been saying, I like to get all new to me used vehicles to a point where I know all the fluids and filters are at the same point, new, and then monitor from there. In another thread, I did my fluids. My fuel and air filter came today from RA. Now I have to get back under that rig. From what I can see on You Tube, the fuel filter is mounted near the fuel tank. Has the squeeze disconnects that can be a pain after being exposed for lots of miles and temps. Thankfully, this rig has spent its life in Oregon where we do not use salt on the roads. I also see that the filter carrier is made of plastic and has a Phillips head screw that squeezes the strap around the filter.
Hopefully the screw just comes right out but will have a couple very large zip ties available if needed. IMO, the in and out spouts should be a different size so as not to confuse but the OUT spout is marked. I will not mix up. I noticed that the you tube guys said to run engine, pull the fuel pump relay and let die and then remove the fuel fill cap and then the pressure would be relieved. Both instances, they removed the line(s) at the filter and fuel went everywhere. All good, I will be prepared.

I will be cleaning the MAF sensor when doing the air filter as well. I have no running problems, just something to do while I have it apart.

So, knowing all this, is there any words of wisdom to share out there. From what I saw, it looks like the best access to the fuel filter is just get the left rear up in the air and there it is, correct? Any info help is appreciated. Thanks in advance.
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
Nothing special. Two squeeze clips and the lines are off. Yeah, that screw for the retainer can be a b!tch. I think I wound up zip-tying it.

Cleaning what MAF? They didn't happen until 2005.

Cleaning the throttle body is also a regular thing.

How to clean your throttle body

Spark plugs? Use only ACDelco 41-103

Coolant?
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
Well, they got it wrong because I know for a fact 02-04 doesn't have it. If you look, there are only two listed, that NTK and UMP. It's not even the right one. This is the one for 05-09 and RA has a whole bunch of different brands:



Not the first time catalogues get it wrong.
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
I thought of that and assumed that port was up on the rail under the hood, like my 05 Z71 but that sure looked like a port cap in the video. I forgot to ask here about that cap. That would allow more control bleeding that pressure off before removing the lines. Great idea.
 

movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
Well, they got it wrong because I know for a fact 02-04 doesn't have it. If you look, there are only two listed, that NTK and UMP. It's not even the right one. This is the one for 05-09 and RA has a whole bunch of different brands:



Not the first time catalogues get it wrong.
You are correct sir. There is no MAF but there is an Air Intake/Charge Temperature Sensor. I pulled it and can get one from RA shipped for $17.42 and I did order it instead of trying to clean it. I ordered the Genuine GM part. Thanks for the info.

By the way @Mooseman, this morning was the first time I went to look under the hood. I was only going by what RA said and I have seen them be wrong before. Again, thanks.
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
Before undoing any fuel line, it would be good to pull the fuel pump relay and run the engine until it dies to relieve the pressure.
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
Before undoing any fuel line, it would be good to pull the fuel pump relay and run the engine until it dies to relieve the pressure.
Yea, standard operating procedure when opening any fuel lines on anything I have ever worked on. Thanks for the reminder and I also noted above that the you tube videos showed that as well and both videos said to open up the fuel cap.
 

christo829

Platinum Donor
Dec 7, 2011
459
Fairfax, Virginia
My fuel pressure gauge (nothing special, I got it at a local auto parts store) has a valve and small hose on it, so I can hook it up to the fuel rail, put a small jar on the end of the hose, and use the valve to bleed off pressure. The jar catches the fuel.

Just figured I'd mention another option for bleeding off fuel pressure. You'll still get some fuel coming out of the fuel filter and pipes when you remove it, but it won't come spraying out, and you can catch that in the same jar, so eventually you can just dump that back in the tank.

...and now I need to go remember where I put the fuel filter I ordered awhile back... SMH...
 

movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
Back at it again today. First thing was the fuel filter that I was worried about the retaining strap that I was thinking would have a screw that would give me fits. As it turned out, the strap was broke loose right at the screw clamp area. The screw was there but the strap was broke clean. No biggee. The retaining clips fought me at first but by then I had removed the filter from the cradle and twisted to gain clip access and it came apart pretty easy. remember, we have no salt on the roads here. The new WIX filter came with new clips and I just used them and then used a large zip tie to attach at the cradle pocket. Reinstalled the fuel pump relay and reinstalled the fuel fill cap and started right up and idled fine with no leaks. I did use the shrader valve at one of the attaching fuel lines to bleed off pressure before disassembly.

Moved on to air filter and that was straight forward but I tore down to and removed the throttle body and I am glad I did. The air intake housing was very cruddy inside and I used the CRC Throttle Body cleaner and a new shop towel to clean and then cleaned both sides of the throttle body, was cruded up pretty bad. Bet had never been done before. At the hinge pivot I used Q-tips and the whole thing was Spic and Span. Reinstalled the assemblies and showed my girl the difference between a clean air filter and a new WIX filter. Started right up and the idle was smoother and accel no longer had a slight hesitation when stomped on it.

Tomorrow, the new ignition switch gets done and then on to the speakers problem. Since I have bought, installed a new GM water pump, GM thermostat water outlet and thermostat, driver's door limiting check strap and driver's door arm rest, all fluids have been addressed and the two listed filters and the throttle bore cleaning. The Air Charge Temp Sensor is coming from RA and then, as I said, the speakers. I will then have this rig where I can depend on it. I was tempted to pull a spark plug or two while down to them but at 70k miles and running fine, I decided to let go for now. I would expect that the plugs/boots will be changed within the next 10k miles.

She is driving it more and getting used to the view spots and really starting to like the rig and again, I looked under the whole rig while under there when doing the fuel filter and again, is dry under there, NO LEAKS.
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
Did you disconnect the battery while cleaning the throttle? You have to do this or it will idle like junk.
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
I did not disconnect the battery when I unplugged the throttle body and removed it. I did the cleaning and reassembled and it started right up and idled fine. Several times during the cleaning process I did open the throttle plate partial and all the way and cleaned thoroughly with Q-tips as well. I fully expected to have to do a relearn road trip but the idle was smooth and at 600 rpm. Drove it 20 miles round trip and no problems were experienced. It had a very slight rough idle and a slight hesitation when accel hard and now both of those problems are gone.
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
It's usually when the A/C is on it will have issues regulating the idle. Alternatively, you can pull the PCM fuses for 30 minutes if you don't want to lose radio memory.

Maybe you had already disconnected the battery before cleaning the throttle body. Cleaning it would have fixed your issues.
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
The a/c was not on but the compressor was cycling at idle at stops and while driving because the defrost was on. Because we still need to address the speakers problem, she hardly ever has the radio on and if she does, she has one station she listens to and if for any reason I have disconnected the battery, she just changes to that station. I get what you are saying though. Sensing the load could need some recalibration but in this case, it appears to be ok and I hope it remains that way. Again, I will say that the very slight rough idle in gear and hesitation when accel problems are both gone.
 

TJBaker57

Guru
Aug 16, 2015
2,241
Colorado
If and when you might have a desire to remove power from the PCM for a reset there is actually just the one fuse to remove, fuse #10 under the hood. You will see it all over the web to also remove fuse #28 but in truth that fuse is fed by the ignition switch, terminal C and is only live in RUN and START. Removing it won't hurt, but it also won't accomplish anything either.


Now if we were talking about the V8 engines, VIN M or VIN H the single fuse to remove is fuse #29 instead of #10.
 

movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
If and when you might have a desire to remove power from the PCM for a reset there is actually just the one fuse to remove, fuse #10 under the hood. You will see it all over the web to also remove fuse #28 but in truth that fuse is fed by the ignition switch, terminal C and is only live in RUN and START. Removing it won't hurt, but it also won't accomplish anything either.


Now if we were talking about the V8 engines, VIN M or VIN H the single fuse to remove is fuse #29 instead of #10.
Again, more great info.

One other thing I noticed recently/yesterday. Since I did the oil and filter change and used Mobil 1 10w-30 full synthetic and my preferred WIX XP filters, the "sewing machine sound" that I hear at idle, is almost non existent.
 

TJBaker57

Guru
Aug 16, 2015
2,241
Colorado
Again, more great info.

One other thing I noticed recently/yesterday. Since I did the oil and filter change and used Mobil 1 10w-30 full synthetic and my preferred WIX XP filters, the "sewing machine sound" that I hear at idle, is almost non existent.

It is unfortunate that we cannot get a true oil pressure value from a factory LL8. The only way to see that is with aftermarket oil pressure gauges/sensors.

My own 2002 4.2 has seemed quite noisy to me since I acquired it 12 years and over 140000 miles ago. I have always used a full synthetic oil although I ise a house branded one.
 

movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
When I roadtested the TB yesterday, after the fuel filter and throttle body cleaning, I also watched the oil pressure. Is almost a duplicate of my 5.3 in my 2005 Z71. Idles at 40-45 psi and when accel will climb to 55-60 psi and then cruises at 45-50 psi. I wish I had the same 3.73 gear that the TB has, in my Z71, it has 3.42 gear. My old 2002 Tahoe LT had the 3.73 gear and I loved it. I did recently get/won a Christmas raffle drawing at Black Bear Performance and got a free traditional tune on my 05. Woke it right up.
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
Don't even bother looking at that pressure gauge. It's fake with PCM generated readings. The pressure sensor is really just a switch so it's really just an idiot light. If it shows pressure, you have pressure (unknown exactly what pressure), if it shows 0, you have no pressure or the switch is defective.
 
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
Have not looked yet. Is the oil pressure switch difficult to get to, like my 5.3, to attach a gauge to?
 

TollKeeper

Guru
Dec 3, 2011
7,342
Brighton, CO
Theres a service port, if I am remembering correctly, near the oil filter with a allen head that you can thread in a external Oil Pressure Sensor?
 

Mooseman

Moderator
Dec 4, 2011
23,693
Ottawa, ON
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movietvet

Registered Member
Original poster
Dec 21, 2022
171
Oregon
One of these days I will look for that oil filter area port. Anyway, Did the ignition switch today. Literally took me 10 minutes tops to do it. There were no torx head screws holding the lower cover at the steering column. The lower cover of the dash was held in place with 2 7mm screws. Popped them out, pulled the lower dash cover down, popped the lower steering column cover off, unplugged the harness and depressed the two retaining clips and it fell out of there. Set the little gear teeth the same as old and reversed the procedure and it was bing bang boom, done.

Went to use my new cooling system pressure tester adaptor at radiator neck and found the threads were boogered at the radiator neck. The new rad cap threads on tight and holds pressure but the adaptor will not thread on and I did look and saw the radiator neck threads are boogered. I double and triple checked the tester adaptor and is the correct one. When do a new radiator, I will worry about it. I know I have no coolant leaks.

Then Fed Ex delivered the new Air Charge Temp Sensor and I installed it in about 2 minutes. Calling it all good now till I attack the speaker problems.
 
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