Location of Schrader Valve on 5.3 L engine

[cubfan56]

This question concerns an 03 Yukon XL with the 5.3 L Flex fuel engine.

I understand there is a Schrader valve used to release the fuel pressure in the fuel line. I want to put on a new fuel filter. My problem is I can't find the valve. I assume it's up on the fuel rail somewhere. If my assumption is corect, can someone tell me if it's in the front or back and on which side of the engine?

Can I do this safely without using a pressure gauge to bled the system?

I haven't looked for the filter yet. Is it under the vehicle, on the frame rail near the tank?

[maxwedge]

Welcome to AF. Don't know if the FF has the same filter location, but it should be l/s near the tank, you also may find a bleed off valve at that location.

[cubfan56]

Thanks, I appreciate the help. It got cold out here in Idaho so I'm going to wait till the weekend to go looking again.

[kh090903]

I just replaced my fuel filter on my 03 Yukon with the 5.3 Flex recently. It is directly under the drivers seat along the inside of the frame rail. I didn't mess with the schrader valve since I didn't have the proper gauge. All I did was take the gas cap off. I used a rag around the filter and didn't notice any extreme pressure when I loosened the line from the filter. There is a special tool that would be helpful to get the filter off if its the factory filter. The aftermarket filters have a different clamp and are a lot easier to remove. On the factory filter, its a four sided interior clamp thats just about impossible to get off without the special tool. Since I didn't have the special tool, I used a wirecutter (be very careful here) to cut off the front of the filter. I then used toothpicks on each of the four interior clamps to hold each while pulling out the filter (what was left of it). This was an unexpected pain, and I would highly recommend the special tool, if you can find it. Unfortunately, you would never use the tool again since the replacement filter clamp is different. Not sure what the dealer would charge, but this is a five minute job up on the lift with the correct tool. I paid $20 for my filter at the dealer.

[cubfan56]

Just to finish off this thread, I thought I'd post what I found out. The Schrader valve is positioned between the two fuel rails under the plastic cover on top of the engine. After removing the gas cap, there wasn't much presure in the line. I didn't use the pressure valve with a drain nozzle,as the repair manual suggested, I just put a rag around it and pushed in the valve with a screw driver. Very simple and not real messy. About a teaspoon of fuel was released.

I found exactly what KH090903 found with regard to removing the old filter. A special tool is required and I found it at the local parts store for $12.00 and it worked very well. But you do have to have it unless you want to do as KH did.

Since I bought the original filter at the dealer I'll need to use the tool again in 30k miles. At that time perhaps I'll buy an aftermarket filter.