Measurements for fuel pump access door (PIC INCLUDED!)

So with having to replace my fuel pump yet again and not wanting to pay a shop for labor again, I decided to do the fuel pump access door under the rear seat. This was the 2nd new pump in a year in a half and its cost me a lot to have it replaced twice. Ran fine Wednesday when I went to work. Try to start it Thursday morning after work and it wouldn't start so I had to have it towed to my house. Being short on cash, cutting a hole was about my only option. Thank god it was somewhat warm outside. So anyways, I removed the rear seat (It took me forever to realize that the two small bolts on the rear passenger corner of the seat had to come out). Peeled back the carpet after removing some plastic. Browsed the forums for a while and could only find info on the 2500 Av's. So I took a wild guess with the 4" grinder and made some cuts and was dead on. Managed to take a pic after the new pump was in and edited the photo to add measurements. Here ya go all! Hope it helps!

Thank you. I haven't had to do a fuel pump yet. But with 175k on her I think I'm on borrowed time.
going to bookmark this page for reference because its the clearest description I've seen yet.

Curious as to what brand of replacement pumps you used.

I just finished mine a couple of weeks ago. I cut the hole, but sadly, the lines were so rusted I had to drop the tank after all. I asked in a post if anyone had issues with any of the pump manufacturers, but no replies. I bought and installed "Spectra Premium SP6026M Fuel Pump Assembly" from Amazon Prime http://www.amazon.com/gp/product/B008VN1LZQ/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1 for just under $200 all in.
So far, it is running very well.
Before picture pump....after picture pump...metal ends that I had to cut open the plastic couplers to get out....

At least you have the access panel now to check on the condition and do preventive maintenance on the lines and pump module. Spray a good coating of rust/corrosion inhibiter every year or two, there are many good products from Boeshield (Boeshield T-9 my choice) WD-40, LPS and CRC.

A lot of the replacement pump modules available out now are all plastic on top, no metal. Not my first choice but if live in a area where they salt the roads it might be the best choice in the long run..

http://boeshield.com/why-boeshield/

Both replacements were airtex pumps with the plastic tops. Living in Northern NY, they put salt on the roads like stupid so plastic is the best option. The first replacement was has acted weird since the day I got it when getting on the throttle hard. Its like it couldn't keep up. But it discouraged me from getting on it too hard and saved me some gas so I didn't complain. Lol. Now its like a new truck!

cbouissey12 said:

Both replacements were airtex pumps with the plastic tops. Living in Northern NY, they put salt on the roads like stupid so plastic is the best option. The first replacement was has acted weird since the day I got it when getting on the throttle hard. Its like it couldn't keep up. But it discouraged me from getting on it too hard and saved me some gas so I didn't complain. Lol. Now its like a new truck!

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The reason I asked was it has been mentioned several times on this forum that it is usually suggested to go with OEM units.

I do not live in a salted area, so I am unfamiliar with concerns for that problem.

It just stands to reason that if a certain brand is showing itself to be less than reliable, then perhaps a different brand might be a better choice.

I have had fuel pumps fail in every GM truck I have ever owned, and there have been several, but all of those have had at least 80,000 miles on them before the first failure and I have never experienced a second fuel pump failure on the same vehicle.

Granted, I have previously had my fuel pumps replaced at a dealer (never again, for other reasons), and I must ASSUME that the replacement units were OEM.

My previous vehicle was a 1999 Suburban and the fuel pump went out at 180,000 miles.

When I traded that one at 241,000 miles it was still going strong.

Having two go out in a year just seems a bit excessive to me, that's all.

Good luck with this one.

Mine just went out after 135xxx it never went completely but I wound up dropping the tank. It wasn't too bad, but took about 2 hours.

My original went out at 160,000 miles and to me if you get more than 100,000 out of a pump your doing good. But like anything electric/mechanical it's going to fail sooner or later. The mechanical pumps that used to bolt up to the block and run off the camshaft used to last 50,000 miles if you were lucky, so the newer electric in tank pumps do a great job IMO.

It's just that the manufactures need to make an effort to engineer/make parts on vehicles  easier to replace/repair so changing a fuel pump that I can buy a factory replacement for $50.00 and takes less than a hour of my time to change it out. I shouldn't have to bring it to the dealer and get a bill for $1,000. Granted everyone does not have the tools or is capable of changing out a fuel pump, but if it was engineered to make replacing it easier it would cost half as much to have the dealer do it and would make the customer much happier.

After dealing auto parts for 7 years, Ive seen my share of defective parts right out of the box or ones that fail prematurely. Nature of the beast I guess. We will see how this one goes. OE one lasted about 150,000 miles. Replacement only lasted about 7,000. Hopefully this one holds up. Seems to be better so far as the truck runs better and seems to keep up under hard throttle unlike the last one. If not, it should only take about 20 minutes to change!

Thank you for posting the image and measurements. I joined the club in cutting my floor. I am pleased with where my cut out landed, I was able to swap the pump easily. If I might suggest a minor tweak to the measurements. The 7" from the plastic back wall and the 15" line that makes towards the front is bang on the money. I'd move the cut from the carpet edge inward to 9 1/4" instead of 8" and let that push the other side over to 18 1/4" instead of 17". That'd really center that sucker. Glad you posted that pic though, cleared it right up for me. Thanks.


Do not cut further on the side I struck out in the text, see  my follow up post.

This is what makes this club so great! Expanding on one persons solution to perfect it even further. This place could be a one stop shop for Avalanche Diagnostics and Solutions!

Txakura said:

Thank you for posting the image and measurements. I joined the club in cutting my floor. I am pleased with where my cut out landed, I was able to swap the pump easily. If I might suggest a minor tweak to the measurements. The 7" from the plastic back wall and the 15" line that makes towards the front is bang on the money. I'd move the cut from the carpet edge inward to 9 1/4" instead of 8" and let that push the other side over to 18 1/4" instead of 17". That'd really center that sucker. Glad you posted that pic though, cleared it right up for me. Thanks.

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Nice clean cut, great job. Now find an AV in a junk yard cut a piece out in the same spot only bigger then trim it so it's about 1" larger all the way aroundand make a access panel. Seal it with a light bead of silicone and your good to go until the next one or just maintenance.

I do like the idea of the doubler you've made, you may have restored any structural strength that was lost by the cut in the floor. Nearest junk yard to me is 90 miles one way, if they even have what I need.

I made some flanges, bolted them with 1/2" 10-24 screws, lock washers and nuts on the under side. The idea is the flanges are 'permanently' afixed. The plate cut out was then drilled and I used the holes for 10-24 clip nuts. Now the plate simply unscrews for access. If the flanges get in my way, I can unbolt them.

This does not restore any strength that could have been lost, the floating plate does not contribute, it is just along for the ride now. The 1/2" corner radius of the cut out will have to allow the stresses to pass around the cut out without cracking. A sharp 90 degree corner could stress crack as the forces transmitted through the material will concentrate in the sharp corners. If I was that worried about it 

I had to cross out my earlier post measurements, there is a piece of heavy structure under the floor near the inside most cut. It would be best to stay away from that. If you flange like I did, adding a 1/4" would be useful but it might make it tight to remove the pump. I attached one pic with a red line for 'do not cut past here' and two green lines for 'if I did it again' I would TRY to cut here. cbouissey12 really did nail it to begin with, his measurements are very good. I'm only suggesting bringing the door side cut closer to the pump. Being a little off center actually works to tip the pump towards you standing in the door removing it.

I deburred all my cuts and holes, and just touched up the bare metal for some kind of rust prevention with a little paint. Wear gloves, another poster wasn't kidding about this metal making razor blades along the edges when you cut it. The metal tape is for dust, moisture or whatever.

I almost forgot! Put a piece of sheet metal on top of the tank, the lines or wiring when you are drilling. Something, even a piece of wood. If you over do it, you will tap the metal or the wood without making a nice hole in your tank, wiring or fuel lines.

Protect yourself! I only had my tank open long enough to put the new pump in. I was outside with no electrical sources, the battery had been disconnected, no cell phone in my pocket and all the truck doors wide open. I had 7/8 of a tank and it fumes up FAST when you open that hole. Use non sparking tools to spin the pump collar off and back on, brass, bronze, phenolic, wood... no steel on steel.

That looks really good! I did a similar thing with the flanges to keep the flap from going below the floor level. I riveted stips of metal underneath then put the flap down, and riveted thin strips on top to secure it down. So it it happens again, I just have to break the rivets to open it. A bead of silicone around it and good to go! Glad this info helped people out.

Not bad. Thanks for the measurements. 

Nice writ up! Txakura, what tool did you use to cut the metal with the nice radius?  Also, If only using a cut off wheel, how careful concerning depth of cut so as not to cut lines/tank etc? Forgive my ignorance, I could go crawl under my av and see but its cold outside lol. Is there enough room for a piece of metal to protect these parts while cutting?

Great job!!!

Thank you so much for the pics and write up . The measurements are spot on! and pictures with measurements are even better. I've got a 06 and only cut three sides and  bent it up, I'll see how it goes  back together as I need to pickup up the pump. Cutting with and oscillating tool made a quick and straight cut. I took the front part of the seat off first before removing the seat, that way it was a lot lighter and easier to get out. Thanks for the help!

Great article, I'm looking to this to my 2002. What year of truck was this done on?

tacomike said:

Great article, I'm looking to this to my 2002. What year of truck was this done on?

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Their signatures say 2002

Glad I found this thread.
Hope I never need it
Looks like it's close to the floor board, would have to be very carefully. Using a angle grinder with all the sparks could be a disaster