Fuel Pump Replacement

[DelCoch]

Fuel Pump Replacement

First of all, I would hook up a jumper wire to the fuel pump test wire and double check the fuel pump pressure. (see below for location of test wire) Also, make sure your battery is fully charged. A weak battery will not power the fuel pump 100% and will cause a no start. If you have over 61 psi when using a jumper on the test wire then you pump may be ok?? If so check your wiring as described in this thread.

Also check this Thread about low voltage

Second, the consensus on this board is to use a Bosch or AC Delco replacement pump.

I’ve included a couple photos from when I replaced my pump, but mine is a ’95 4x4, which has a different type pump, but the gas tank, etc. should be the same. Probably take about 4-hours to replace the pump the first time you do it.

On a 4x4 - Remove the spare tire – Remove the skid plate under the gas tank if so equipped. Remove the left rear wheel and make sure you have good support, (jack stands on a solid surface) under the vehicle so it won’t fall on ya. Remove the neg battery cable.

The fuel line nuts that connect to the sending unit and fuel pump at the gas tank freeze up with rust. The line nuts get rusted to the fuel line and when you try to turn the line nut the fuel line will twist. Thus, I suggest getting a good penetrating oil from your auto parts store,- WD-40 won’t do it. Spray the line nuts up real good before trying to disconnect them. If the line starts to twist spray it up real good and let soak for a couple hours, maybe overnight.

Also, spray the 15mm nuts on the front and rear gas tank support straps with penetrating oil. These also get rusted and the ends of the straps have been known to twist off.

There is no drain plug on the gas tank, and the tank will weight well over 100 pounds when full, not fun when lying on your back under your vehicle, even with only a couple of gallons of gas in it. No problem I thought, just stick a small rubber gas hose down the filler neck and pump the gas out, right? Wrong!! Where the filler tube connects to the fuel tank, there is a little plastic ball inside the filler neck, which is only a couple millimeters smaller than the inside of the filler neck. It lets gas go into the tank, but not a small hose. (see photo) The purpose of the little ball is to prevent gas from running out of the tank if the vehicle turns upside down, as the gas will press the ball against a seat and seal off the filler neck. Next I thought I would disconnect the filler tubes and remove them from the vehicle. Wrong again. The filler tubes have a bracket made onto them that is bolted to the frame where they cross over the rear axle, and there is not enough room between the body and the bolt to get a wrench on the bolt.

So, before you drop the tank, try to get all the gas out of it. This can be done two ways:

1) If your fuel pump still works half way; There’s a fuel pump test wire under the hood on the driver’s side next to the fender, under the hood hinge. It’s a red wire that has a gray or black plastic cover on the end of it and it just hangs there next to the electrical junction box, not hooked to anything. Put a live 12 volt jumper wire to it and the fuel pump will run if it's not toast. If the pump runs then disconnect the fuel line at the fuel filter, (which is located on the inside of the frame under the driver’s door) put a hose onto the gas line coming from the tank and into a container. Then connect the battery cable, run the fuel pump to empty the tank and then disconnect the battery cable again. Or, you can connect an auxiliary gas pump to the gas line and pump the gas out of the tank.

2) Or, loosen the nut on the rear gas tank strap to lower the rear of the tank just enough to disengage the rubber hose on the filler neck at the rear of the gas tank, then put a small hose into the tank and either use an auxiliary gas pump to pump the gas out of the tank or you can use a siphon. (Whatever you use, it must be designed to pump gas – otherwise you might have a big, big fire) Fire is a great danger when removing a gas tank. I’ve seen repair shops burn down when gas is spilled and a shop light falls into it.

After the gas is out of the tank, if not already lowered, lower the rear of the tank 2-3 inches. On the top rear of the tank towards the left rear wheel, disconnect the rubber hose from the plastic fuel vapor relief valve – see photo for location. Also disconnect the wire connector that goes to the fuel pump. Use a set of flare nut wrenches and a secondary wrench on the fuel lines to loosen them at the fuel pump.

Loosen, but do not completely remove the front gas tank strap, just drop the front of the tank down 2-3 inches and reach around the front of the tank under or through the plastic shield on the front of the tank and remove the hose from another plastic vapor purge valve located on the front left of the tank.- (see photo for location) Usually this plastic connection on the front valve, from people not knowing its there, gets broken off when the tank is lowered. A new one at the dealer is 20 bucks.

The plastic shield on the front of the tank won't come off until the tank is out of the vehicle.

When you are ready to drop the tank, use a floor jack to support it and remove the straps.

Once you get it removed be sure to clean all the dirt and gravel from around the sending unit and locking ring, as you don’t want this dirt to fall in the tank when you remove the pump.

Unless the pump has been replaced before, you will probably find the flange and locking ring on top of the sending unit having a thick coating of some kind of epoxy on it. I had to take a hammer and screw driver to chip all this crap away and then still had a hard time getting the lock ring to turn. After you knock down the 3 tabs, it turns clock wise – See photos. Use a brass punch to prevent sparks when hammering on these rings. After replacing the pump I sealed mine back up again with epoxy glue to keep water out of the tank.

Remove the retaining ring/locking ring from around the sending unit pipes and wire harness. Once free, the sending unit/fuel pump simply comes up and out of the tank. As you withdraw it from the tank it may require a 180 degree twist to get the pump out of the tank. Make note of how the pump sets in the tank and which way the float is pointing before you remove the pump. The new one needs to go back in the same way, with the float facing the same direction.

Make sure the new o-ring gasket that comes with the new pump is the right size, same size as the old one – if not, pick up one at the dealer. They are about 10 bucks. Lubricate the new gasket with oil when installing it.

Follow the directions that come with your new pump and install in reverse order of above. Use the floor jack to hold the tank up while connecting everything. Don’t forget to connect the front hose on the purge valve. While under there replace the fuel filter also.

Once everything is connected and the tank re-installed, put at least 8-10 gallon of gas in it and reconnect the battery cable. You will have a lot of air in the fuel line, so I would again put a jumper on the fuel pump test wire and check the fuel pump pressure again. Once you get over 61 psi remove the jumper wire and it should start up.

Someone else please jump in here with what I missed,

Good Luck

[rockethobbit]

Will these procedures work on a 96' S-10 V6 2WD ExtCab?

Does anyone have any other links to how to remove the tank? This seams to be the hardest part for me. Trying to disconnect the cables and hoses at the top of the tank while it's still mounted appears to be impossible when I look at it.

I heard of a guy who just cut a hole in the bed to get to it and that seemed temping rather than hassle with the tank removal, but if I can find clear instructions on how to get it out I would prefer to remove it.

Thanks.

[randy78]

61 psi ?

who told you that ?

lol

[randy78]

Originally Posted by rockethobbit

Will these procedures work on a 96' S-10 V6 2WD ExtCab?

Does anyone have any other links to how to remove the tank? This seams to be the hardest part for me. Trying to disconnect the cables and hoses at the top of the tank while it's still mounted appears to be impossible when I look at it.

I heard of a guy who just cut a hole in the bed to get to it and that seemed temping rather than hassle with the tank removal, but if I can find clear instructions on how to get it out I would prefer to remove it.

Thanks.

to drop the tank on a pickup you just remove the front tank hanger blt in the frame and then the rear strap bolt and lower it down enough to get all the hoses off, its a kind of tight clearance but you can do it

jackstand the tank side of the truck up soe to get extra tank to ground clearance, it will help out a bit

good luck

[blazee]

Originally Posted by randy78

61 psi ?

who told you that ?

lol

That is GM spec, and fairly accurate. Any less than 61psi causes hard starting. Less than 55psi and it won't start without starting fluid. Less than 43psi and the engine won't run at all.

[oirole]

im trying to drop the tank on a 99 jimmy. the fuel pump is sitting here and ready to go in.

has anyone out there ran into stripped bolts on the fuel tank straps? i have, and im wondering if i should get the SAW-ZAW out to cut them off. then i would have to grind off the heads of the STRIPPED bolts, and get the cores out. then finally replace the straps and bolts when im done.

this turns this 1/2 day project into a full day project.

any suggestions would be appriciated?

[Blutarski]

Originally Posted by oirole

im trying to drop the tank on a 99 jimmy. the fuel pump is sitting here and ready to go in.

has anyone out there ran into stripped bolts on the fuel tank straps? i have, and im wondering if i should get the SAW-ZAW out to cut them off. then i would have to grind off the heads of the STRIPPED bolts, and get the cores out. then finally replace the straps and bolts when im done.

this turns this 1/2 day project into a full day project.

any suggestions would be appriciated?

Any help on this? The rear strap bolt that attaches to the frame rail, with the threads hidden inside the frame, simply spins - I'd cut it, but the whole spark shower in the presence of gas vapor.... hmmmm

[Blutarski]

Figured it out, just cut the bolt - use a regular hacksaw if needed, shouldn't be an issue. When you buy your pump, just buy the short end of the front strap, plus the replacement bolt and clip to go with it(if salt and rust are an issue in your area), it will all make sense. Also get a new lock ring for the pump, as that will probably be a rust pile as well.
Good luck.

[peterjon1]

Just a FYI--dealer wants $300 for that filler neck. I got my replacement (when mine rusted out) from a jy for $20. Parts guy sez "No wonder we don't stock those!"

[JasonSpaeth]

I do not understand. I thought the grey test lead wire was on the driver's side near the brake master cylinder. You are stating that it is behind the fuel pump relay which is in the glove box. I do not see access to get behind the relay to get to any wire. And, on the engine bay side access is blocked by the heater fan motor.

What I did do - and I am not sure if this tells us anything - is I hooked my voltage tester to the positive terminal of the battery and onto the grey wire at the fuel pump/tank. With the key on, it registered 11.68 volts.

Does this tell you anything? What do you suggest I try next? Sorry if I am not following you on the grey wire thing - I am just confused. Thanks.

[dtb2253]

It appears the fuel pump is out on my sons 2000 S-10. Great information here, but i have 2 more questions:

1. His is a 4WD 6 cyl. Where would the fuel pump test wire be located on my vehicle?

2. Looks like it might be easier to raise the cargo box rather than drop the tank. Did this on a 1988 S-10 and it worked very well. Any input regarding this approach?

Currently charging the battery (was low ~10V) and waiting for it to warm up here - its 8 degree F. Any other input would also be welcome.

Thanks all.

[old_master]

The fuel pump prime connection on a 2000 is right next to the fuel pump relay in the underhood fuse panel. There is a single, recessed, unused, terminal in the fuse panel. When you apply battery voltage to it, the fuel pump should run continously.

Two ways to service the pump: pull the box or drop the tank, either way works well.

Key ON, Engine off, pump running, pressure must be 60 to 66psi. After the pump shuts off, pressure must remain above 55psi. Post your results.

[djjm3]

Also.... Black & Decker Has a JackRabbit Pump Part #134000-03, cost is $37.00...(call 800.544.6986 and they can find a service dealer close to ship to you) Clamp the tube to the front end of the fuel Filter and you can pump the gas Safely .....

[01-Cavy-01]

how would i go about testing and figuring out how much psi the pump is running at, i have to change the pump since the old one gave out on me but i was thinking this would be a simple drop and go replacement..is it needed to test the pressure of the pump after installing the new one or is the pump only tested when trying to diagnose causes for hard starting?

[Knight stick]

I have a 2000 S10 4.3 Vortec 4WD 57,000 miles. My fiancee informed me one day that the last time she started the truck, the check engine light came on. When I checked the truck, the engine would turn over but it would only run a few seconds with starting fluid. The truck was not being driven since I needed to replace U joints & replace the tires. I could not locate the fuel relay switch. I priced fuel pumps in my area. They are a special order & will cost $343.00 to $369.00 depending on the parts store. I could hardly believe the price!!!! I have thought about cutting a hole in the bed to allow access to the fuel tank & sealing it back after I had installed the fuel pump. Has anyone attempted this....successfully??? I welcome any information.