Rick's Free Auto Repair Advice

Replace fuel pump

Fuel pump replacement instructions

You can replace your fuel pump and save several hundred dollars. But there’s gasoline involved here and some very specific procedures. Screw them up and you could wind up toasted to a crisp or damaging other parts that will cost more than if you had paid a shop.

CAUTION: You’ll be exposing your work area to raw fuel vapor. You must perform this job in a well-ventilated area away from sparks and open flames. That means you can’t do it in a closed garage and you can’t have a space heater running nearby.

To learn more about symptoms of a failing fuel pump, read this

Relieve fuel pressure before disconnecting fuel lines to fuel pump

The fuel lines on all fuel injected vehicles retain up to 50-psi. Disconnecting a fuel line can soak you in gasoline. Start by removing the fuel cap from fuel tank to relieve any tank pressure. Then remove thee fuel pump fuse from the fuse block or disconnect fuel pump connector under the vehicle. Start the engine to operate the fuel injectors and bleed off fuel line pressure. The engine should start and stall immediately. Check your fuel gauge and jot down the amount of fuel in the tank. Then remove the key from the ignition and disconnect the negative (-) battery cable.

Determine fuel pump access

Every vehicle is slightly different so consult the shop manual for your particular car or truck. Some vehicles have an access panel under fuel pump access coverthe back seat that eliminates the need to drain and drop the fuel tank. If your vehicle has that, consider yourself one of the lucky ones. If your vehicle doesn’t have an access cover, you’ll have to drain and drop the fuel tank as the first step.

If you have to drop the tank, start by referring to the note you made in the previous step where you check the amount of fuel left in the tank. The reason for this is that you’ll have to disconnect the fuel tank filler neck from the tank and if the tank is more than half full when you disconnect the filler neck, gasoline could pour out of the tank and spill all over the floor.

How to drain a gas tank

First, figure out how much gas is in the tank. If it’s near fuel gauge and fuel pump replacementfull, you may need as many as five 5-gallon buckets with snap on lids to hold the gas. Don’t start this job without taking that into account.

There are three ways to drain gas from a fuel tank:

1) Siphon or pump. This is easier said than done because all vehicle fuel tanks are equipped with anti-siphon features. To bypass those features, you’ll have to snake a small tube past the anti-siphon mechanism. For the best way to do that, check with a vehicle specific user forum and ask the users for the best approach. Or check for a youtube video. Once you have the siphon tube in place, start the flow and fill the buckets.

2) Use the fuel pump itself. This assumes that the pump still works. If it does, disconnect the high pressure fuel line in the engine compartment and connect to a drain hose and a bucket. Remove the fuel pump relay and jumper the contacts so the fuel pump will run when you turn the key to the RUN position. CAUTION: running a fuel pump down to the point where the tank is empty can damage the fuel pump. Only use this procedure if you’re planning on replacing the pump anyway.

3) Remove the drain plug if equipped. Yeah, some tanks have a drain plug. The biggest mistake DIYers make is not having enough buckets handy to handle the number of gallons of fuel left in the tank. If you don’t pay attention to this point, you’ll be bathing in gasoline and possibly wind up toasted.

fuel tank drain plug and fuel pump

Fuel tank drain plug

Disconnect the fuel tank filler neck

Before you can drop the tank you’ll have to disconnect the fuel tank filler neck. The

fuel tank filler neck and fuel pump

Fuel tank filler neck connecting hose

connection to the tank is usually a rubber hose with clamps. The hose will be slightly “welded” to the tank fitting, so you’ll need to loosen it

heater core replacement

OTC 4521 Hose Removal Tool New

with a hose loosening tool like this.

 

 

 

 

fuel tank and fuel pump

 

Disconnect the fuel tank straps

Soak the fuel tank strap bolts in rust penetrant like PB Blaster or Liquid Wrench. Don’t use a wimpy all purpose lube like WD-40—it’s a lube, not a rust penetrant. Place a large 3/4 “ piece of plywood on your floor jack and raise it to the tank. Then remove the fuel tank strap bolts, drop the straps and slowly lower the tank, but just partially.

Reach above the tank and disconnect the fuel lines. Some require a special removal tool. Don’t try to force these fittings—they’ll break. Also, be careful with plastic lines. If you break them, you’ll need special tools to repair the break.

Next, disconnect the electrical connectors to the fuel pump and fuel tank pressure sensor, if equipped. Then you’re ready to disconnect the fuel tank EVAP hoses and possibly the charcoal canister. Once everything is disconnected, lower the tank to the ground.

Remove the fuel pump locking ring

This next step can cause dirt and grit on the top of the tank to fall in once you remove the locking ring. So use compressed air and rag to blow off all dust and dirt. Get it clean before you proceed.

The fuel pump module is held in place with a fuel pumpremove fuel pump locking ring locking ring. Some tool companies make a special tool for each make and model, but you can often get by using a small cold chisel or wood block and a rubber mallet. Locate the chisel on one of the locking ring ears and tap it until it rotates. Once it’s loose, remove the ring.

Lift out the fuel pump module

The fuel pump is usually located inside a plastic tank replace fuel pumpmodule that also contains the fuel level sending unit and float. Mark the orientation of the fuel line connections before you lift the module out. That’ll make installation a little easier. Then lift the old module out completely.

WARNING: Most repeat fuel pump failures are caused by failure to clean the tank before installing the new pump. Not kidding!. You fill your tank about 100 times every 25,000 miles. That’s 100 opportunities to get crud in the tank—crud that clogs the screen filter, or worse yet, gets PAST the screen filter and into the pump impellers. You’ve come this far, take a look inside the tank and check for crud. If you see any, clean the tank!

Install new fuel filter

Now matter how clean you think you’ve been, you’ll replace fuel filteralways drop some grit into the tank. So replace the in-tank fuel filter and screen with a new fuel pump.

Install the new fuel pump module

This is where you need patience. The new module contains a float arm that must be angled into the tank properly. If you rush this step and try to jamb the new fuel pump module in place, you can bend the float arm, which will give you incorrect fuel level readings.

fuel pump module showing the names of each part

The fuel pump module housing contains the fuel pump, pulsator and fuel pressure regulator, filter sock, fuel level sensor, float and float arm, inlet and outlet connections, and springs to keep the unit at the bottom of the tank

Once the float arm is inside the tank, lower the fuel pump module so it’s flush with the top of the tank and a new O-ring. Never re-use the old fuel pump O-ring! Then install the locking ring and rotate it into the locked position.

 

Reverse the removal procedure

Lift the tank enough to reconnect the lines, filler neck, EVAP hoses and electrical connectors. Make sure any rubber isolation pads that were on top of the tank are still in place. Then lift the tank up fully and secure the tank straps. If the straps are rusted, replace them now. They’re cheap.

Test the new fuel pump

Reinstall the fuel pump relay and connect the negative battery terminal. If your vehicle has a variable speed fuel pump with a regulator, you’ll have to reprogram to let the regulator know you’ve installed a new pump. Add about five gallons of gas to the tanks and check for leaks.

Turn the key to the RUN position for a few seconds to hear the pump run. Repeat the RUN/OFF key cycle to fill the fuel line all the way to the fuel rail at the engine. That’ll reduce cold cranking time. Then start the engine and check for leaks.

©, 2017 Rick Muscoplat

 

 

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Posted on by Rick Muscoplat


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