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ravingmadman
10-01-2009, 04:57 PM
Hey all!! First real post here. I just bought a 1999 4dr, 4wd, shaved, 4" suspension lifted on 33x12.5R15's, custom blue ho for my wife from a guy who really abused it. So far in the couple weeks we've had it, it has left my wife stranded twice, needing a new alternator, and a new fuel pump. It also needed new everything brakes. I couldn't find anyone with any info on how to swap the fuel pump, and the haynes manual was pathetically inaccurate. So here's how I did it for the cost of parts ($250), saving a good $600.

You need:

Metric socket set
2 crescent wrenches
Flat head screwdriver
Jack Stands, or other large blocks to hold up the fuel tank
Wire cutters
Wire Connection Crimpers
Wire Strippers
Pressure fitting disconnector tool (rent from O’Reilly for a couple bucks)
Hammer
Buddy to laugh at you, drink your beer, and turn the ignition on once in a while
Beer
Fuel Pump Relay (~$8)
Fuel Filter (~$10)


DON’T ORDER/PURCHASE THE FUEL PUMP YET!!!!!

Replace the fuel filter (need to do it anyway, to keep the pump warranty):

Disconnect the negative/ground cable from the battery
Find the filter under the driver’s side, just in front of the fuel tank, inside the frame rail.
Unscrew it, involuntarily get gas in your mouth, eyes, nose, and screw the new one in.


Replace the fuel pump relay:

Under the hood, driver’s side, halfway back, under the “Relay Panel.” Sitting in the driver’s seat, it would be the 1” x 1” cube furthest from you, furthest to the right, with 5 pins, marked 85, 87, etc.
Connect the battery, turn the ignition on, listen for the pump to operate for 2 seconds. If no pump whine, proceed. If you hear the pump, and you didn’t before, hit the starter, see if it goes!!!


Replace the Fuel Pump:

Disconnect the negative/ground cable from the battery
Disconnect the filler & breather pipes (hoseclamps; flat head screw driver) from the rear of the tank, siphon out as much fuel as you can. Always have beer ready, if siphoning by mouth. I paid $5 for a siphon kit at O’Reilly. ...Worth it...
Support the tank with blocks of some sort. I used jack stands with marginal success.
Undo the two steel bands holding the tank on.
Lower the tank about half way using a jack if you need. The tank will have to move rearward to clear the frame member at the front of the tank.
Look at the code (i.e. “GFU”) on top of the pump. Call your favorite parts houses, and see if someone has one on the shelf, or get one ordered at this point (roughly $220). There are 2 kinds, and you can’t tell without the code on the pump.
Use a flathead screwdriver and disconnect the 3-wire harness at the rear of the tank, and the 4-wire harness off of the pump in the middle of the tank. Use the pressure fitting disconnector tool (5/8th?) you rented to remove the fuel line couplings. You’re going to get gas everywhere. (BE CAREFUL!!! If you damage these lines, you can’t replace them; no one makes them. If you damage the inner retaining clips, like I did, Napa sells replacements for a couple bucks, but you’ll have to bring in the fuel line (disconnect at the fuel filter, and the supply line comes out easy) to show them what you need.)
Take a breather, drink beer, do a sanity check here. The fuel pump harness should be a square harness with 4 wires. If it is a rectangle, your pump has already been replaced at least once, and your wires will be different colors except the grey wire. With a multi-meter, connect the leads to the grey wire in the fuel pump’s wiring harness and ground. Have the buddy who is drinking all your beer turn the ignition on. You should see 12 volts for about 2 seconds. If you don’t, your fuel pump isn’t getting power, and you’re chasing your tail. Try something else, but don’t continue here.
Lower the tank to the ground
Use a flathead screwdriver and hammer to turn the retaining ring, making sure as you loosen the ring, you push the little plastic catch the out of the way. You’ll see it. The pump is spring loaded, and will pop up a couple inches when free. Pull the old pump out.
Your old pump will have a square harness. Your new pump will have a rectangular harness. Why? Because GM hates you. But this isn’t too bad. Drink more beer. The square harness, if you rub the dirt off of it, will have labels a, b, c, d on each wire. The new rectangular harness will have a & d on either end, it is alphabetical. Cut ‘A’ from the old harness, and splice it to ‘A’ on the new harness. The wire colors will not match up. The wire gauges will not match up. It will work anyway. Why? Because GM hates you. Splice the rest of your wires, drink more beer.
Do another sanity check before you put the pump in gas, and void the return- connect the battery, connect the new harness to the new pump, (wash your hands) hold the pump, and have your buddy turn on the ignition. The new pump should roar for 2 seconds. If it doesn’t, you failed somewhere.
Lube the new gasket with the new goop that came with the new pump, and install the new pump in the tank. You’ll have to push it down, and then get the retaining ring started again, and then hammer screwdriver the ring into place. This is a bitch.
Lift tank half way, and connect fuel line pressure fittings (no tools, just push them on), rear harness, pump harness, and front pipe.
Lift tank all the way, attach the steel bands that hold the tank up, connect filler & breather pipes.
Fill the tank with 5-ish gallons of gas and check for leaks from filler/breather
Connect battery, turn ignition on, listen for 2 second pump operation, check for leaks
Turn ignition off, listen for 2 second pump operation, check for leaks, then on again, listen for 2 second pump operation, check for leaks, turn ignition off, listen for 2 second pump operation, check for leaks.
Pour a little beer on the ground in homage of GM’s recent bankruptcy, and start your truck.

:drunk:

Blueridgerunner
12-01-2009, 04:53 PM
great info. Thanks:hands:

Effeckt
12-01-2009, 05:18 PM
Anyone know if this write up applies to the NBS Tahoe's as well? If it does I would tackle this at some point to fix my fuel gauge issue.

Mild
05-29-2010, 02:03 PM
working on this now. having an issue with the "Pressure fitting disconnector tool" but working on it.

BlizzardX23
05-29-2010, 02:04 PM
Stickied

Broken Truck
07-13-2010, 02:43 PM
Good post. The Haynes manual really lead me wrong on this repair. I ended up jacking the truck up on all four corners and supporting each corner with 2 concrete blocks and a block of wood. You NEED the space! And like the posters says..... don;t buy the pump until you get the old one out. Look for the GFU or other code and then buy the pump. Careful touching the code. It can wipe off very easily.

hoondueces
08-09-2010, 11:16 AM
I bought my tahoe a year and a half ago. The fuel pump was one of the first parts I needed to replace. GREAT write up. I wish I would have been apart of this forum when I went thru that...I did it in my driveway on jackstands.

scott_white85
08-27-2010, 09:40 PM
These are the basic steps and most tahoes are of similar part structures so it applies to all. It is indeed a good how to replace a fuel pump (http://www.automd.com/62/how-to-replace-a-fuel-pump/) article, car repair noobs would find it easy to follow. a little more visuals would have been nice.

TonyJ
11-21-2010, 08:01 AM
Thanks for the writeup. It's hard to believe nobody sells a pump that just plugs into the harness. Time for a little research...

T-Bagg
12-26-2010, 04:24 AM
Why can't manuals be written like this?

Electrichorseman
04-18-2011, 09:08 AM
Ravingmadman,

Thank you! We need more posts like this!

Ken C.

jonnytahoe
04-19-2011, 06:11 AM
I like the fact that you point out that there will be "fuel everywhere". I think I'm just going to change mine now and get it over with. I wont pay 800.00 either. Let's see, a 12 pack is what, 5 bucks. wow that's alot of beer!! I sure miss going to Champion Auto and buying a mechanical pump for 25 bucks.

gulleyman
04-25-2011, 02:28 PM
Does anyone know what the difference is between the fuel pump (complete unit) for a 2dr and a 4dr? No one seems to have the 2dr pump assemblies in stock, wonder how different they are...

retorq
04-25-2011, 04:58 PM
Probably the depth of the internal units ... the rest is more then likley the same.

gulleyman
04-25-2011, 06:24 PM
Probably so, guess I'll just have to wait for the parts to come in...

retorq
04-25-2011, 07:24 PM
Pulls yours out and go down to the parts store and see about comparing them side to side ... or you can just replace the pump part.

gulleyman
04-27-2011, 12:35 AM
Thanks SO much for this thread, I replaced mine today. All the info I needed was right here. The only issue I ran into was that the 2dr's had a different pump than the 4dr's and I had to order the pump and the sending unit/ floater separately. Having never done this before I didn't know how to put the two together and read four pages of mind numbing instructions just to learn to put the pump in with two hose clamps and attach the harness...sheeez

Love this forum!

Spade
02-02-2012, 09:26 PM
subscribed

Gzes
02-04-2012, 09:21 PM
cool too bad im jus payin about 150 for the fuelpump and instal... and a little more for a new floater

gulleyman
02-09-2012, 01:33 PM
Thought I'd mention that a couple of weeks after what was thought to be a successful installation my truck started to stall out. I took it to a friend of mine who looked at it and advised that the hoses that come with these kits are almost always too short, he replaced the hose and it worked great. Happy tinkering ya'll!

maxim9691
03-01-2012, 08:26 AM
Nice guide- had a local shop replace mine for $400 and after reading this I feel better about the cost.

99Yukon4x4
04-03-2012, 10:35 PM
Good write up, but question for anyone. I just did mine (2nd time in a GM product), and got the old one out, and put the new one it, got the wiring harness figured out. Now, I went and put gas in it, and found that it would really not go past 1/4 tank. I pulled the pump again (I had cut an access hole in the floor board, since my bolts and straps were not being friendly), and my tank was damn near full. I have a 4 door 4x4 Yukon SLT, could I have gotten either a bad fuel pump, or the incorrect one?

Thanks!

ajaxnxs
04-03-2012, 10:39 PM
Had mine replaced today

Sent from my SAMSUNG-SGH-I727 using Tapatalk

99Yukon4x4
04-04-2012, 10:07 AM
After getting the wiring schematic for the original plug (square), and going over the new plug harness, it is not as easy as going A to A, B to B, C to C, and D to D. Mine was color coded to match both harness's. I did it the above way, and it thru a check engine code, and with a full tank, it was reading 1/4 or less. Switched wires, and engine code went away, and fuel level went accurate. Not sure if it is the same with all units, but this is how it worked for me.

xanatost
04-04-2012, 01:02 PM
When I did mine I put an external pump on mine. If it goes out again then I don't have to drop the tank. On my old truck it took me about 15 mins to chance it out when it went out for the 2nd time. Just an idea for those who are keeping there for a long long time.