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Replacing broken fuel pump studs

Lets face it, our cars are old. We've all got rusted bolts in various places that end up twisting off. One of the more unpleasant places for this to happen is on the fuel pump cover plate. The studs are built into the fuel tank and can't just be pulled out. They have to be drilled out and replaceed with a new stud or bolt. The ugly part of all this is all the grinding sparks flying around gasoline. This is how I dealt with my broken studs.

Parts needed
Three 6x30mm flange-head stainless steel bolts & nuts or equivalent.
JB Weld under water formula (comes as a stick).
Possibly a new fuel pump cover gasket (only available from the dealer when I looked.)

Tools needed
Well ventilated work area
latex gloves
wire brush (optional)
24mm socket for fuel tank drain plug
14mm open-end wrench for fuel line
19mm open-end wrench or vice-grips for fuel line
8mm socket for fuel pump cover nuts
pliers or vice grips
Dremel or similar cutting/grinding tool
Drill and 1/4" bit
Sand paper (optional)
Floor jack
Wet/Dry shop vacuum
Phillips head screw driver

Time needed
One to Two hours.

The very first thing I did was remove the negative battery cable. Odds of an electrical spark are slim but it would be stupid to take a chance.

You'll also want to wear latex gloves any time you may end up touching gasoline.

After disconnecting the battery, remove your gas cap and drain any gasoline left in the tank. The drain plug is located on the driver's side rear corner. I brushed all the debris off the drain area with a wire brush and used clean pans to catch the gas so I could reuse it. I also jacked the right side of the car two feet off the ground to drain as much gasoline out as I could. You can leave the plug in loosely if you want the gas to drain slowly or remove it completely to drain it faster. Just be sure you have a pan large enough to hold all the gasoline that comes out.

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After the tank has drained as much as possible, remove the fuel pump assembly. To do so, pull the two screws holding the access plate and disconnect the power cable. The release mechanism for the clip is on the underside of the harness. Just reach underneath, press on the tab and pull the clip out.

Next you will need to remove the hard line leaving the pump cover. A 14mm wrench fits the small side and a 19 mm should fit the large side. If not, use a pair of vice grips on the larger nut. DO NOT try to pull the line without two wrenches. The line going into the pump assembly is thin and will crush or twist off if you don't use two wrenches. A little gasoline will pour out of the line once it is disconnected.

The small canister on the right of the opening will need to be disconnected from the pump cover as well. The easiest route for this is pulling the rear hose off the canister, bending the mounting tab inward and then pulling it up off the tab. Leave the front hose connected and move the canister towards the front of the car to wedge it out of your way.

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After that, take your 8mm socket and remove how ever many nuts you have left on the cover plate of the fuel pump and pull the whole assembly out. The floater for your gas gauge will snag, just pull the wire back gently and pull the fuel pump assembly up out at an angle. Set the fuel pump assembly aside and use your shop vacuum to suck out any gasoline left in the tank.

Check your shop vacuum manual to see if it can safely vacuum up flammable chemicals. My Craftsman 5.75hp wet/dry vacuum did the job nicely. I also made sure to suck the gasoline out slowly just in case.

After the tank is empty and fumes have dissipated you are ready for the next step, cutting those broken studs off. For added protection I used a cap over the outgoing fuel line and a cap over the fuel tank. The cover go my grease container was just the right size to cover the gas tank hole without interfering with cutting off the studs. I clamped the rubber line in the bottom right up and out of my way. I also hit the whole area with some water to wash any gasoline away.

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You're ready to cut the studs off and grind them flush. I used my Dremel and a cut-off wheel. There isn't much space to work in so if you don't have a Dremel find something suitable. Checker Auto might still sell a $20 unit like a Dremel if you're desperate. You could also use a small hack saw or file if you're patient enough.

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After the studs are cut off and ground flush put the fuel pump assembly back in and put a couple nuts back on to keep it from moving. You'll need a drill and 1/4" bit now. Use the cover plate as a guide to drill out the old stud holes. Be careful not to drill out the three smaller holes where the fuel pump gasket comes up through the cover plate. Look for the shiny spots you just ground off and you'll be fine. Be sure to drill all the way through the tank as you'll be putting new bolts in through the bottom.

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Once you're done drilling your new holes remove the pump assembly again. Now you will need to grind down the burrs left inside the tank from drilling out the old studs. I tried sandpaper and changed over to using my Dremel & cutting wheel at low speed so I didn't create any sparks. These holes need to be clean and flush for the flange head bolts to seat properly.

Before installing the new studs clean any debris out of your tank using your vacuum cleaner.

Once you are satisfied with the holes you drilled and the tank is clean you're almost ready to put in your new bolts/studs. Before moving on, reinstall the rubber cover-plate gasket. The gasket fits over the bolts very snugly and will help hold them in place while you are working. Now to mix up your JB Weld. Follow their directions for applying it. I used about 1/4" of the stick for three bolt heads and had a lot left over. Roll the putty out into worms and wrap it around the underside of the bolt flange before inserting it up through the tank and gasket. Push the bolt firmly into place and squeeze the putty around the head.

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After waiting 15 minutes gently install the pump cover plate again. Make sure that the bolts are nice and straight in the holes.

Give the JB Weld a few more minutes to cure and then gently tighten the flange head nuts down onto your new studs. If you twist too hard too early the JB Weld will let go of the bolt and it will spin or fall into the tank the next time you pull the fuel pump.

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JB Weld says their goo is fully cured in an hour or two. I gave it about 15 minutes before torquing the new heads down and reattaching all the fuel lines. Be sure you reattach the outgoing line AND the green bell with the rubber lines. Put the gas tank drain plug back in, and fill the tank back up. Before putting the access plate back on, hook up the pump wiring and start the car. Go look for any leaks in the lines. If there are none put the access plate on and go clean up, you're done. If there are leaks, tighten the lines or use plumbers tape on the threads.

From start to finish this job took me about 1.5 hours.
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15+ Year Contributor
Jun 16, 2005
Durango, Colorado
Just thought I'd add that after having done this and driving around for a while my fuel trims were much more stable and happy. Making sure your fuel tank is sealed makes a much bigger difference in performance than I thought it would!


DSM Wiseman
Feb 3, 2002
Boulder, Colorado
You would have been much safer with a full tank of gas that a drained one. Fuel taks car continue to fume for quite a while after the gas looks gone and the the fumes that are deadly. It's pretty hard to light liquid gasoline. A magnet also helps to collect the metal bits when you drilling so that don't fall into the tank.

Nice write up.

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