Installing an In-Tank Fuel Pump
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© 2001 Brian F. Schreurs
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Never listen to those who say it can't be done, unless they have a pegleg to prove it.


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The single biggest problem with running a supercharger is the immense amount of fuel it requires when it's providing boost. Letting an engine run lean is a good way to burn a valve or put a hole in a piston, so it's a Very Bad Thing. Since we're installing a Vortech S-Trim supercharger on the visiting 1995 Ford Mustang GT, we decided discretion was the better part of valor and planned to upgrade the in-tank fuel pump.

To ensure that there would be no future problems, we went with a 190-lph (liters per hour) in-tank unit by BBK Performance (#1606). At least, it's packaged by BBK; the unit itself is made by Walbro, the same manufacturer as the original stock unit. Installation isn't hard, although it's smelly; the only specialized tools are a brass punch and two Ford fuel line disconnect tools: 5/16" and 5/8". It really helps to have a transmission jack, but you can get by without.

Once the gas tank is lowered this far, it's not too hard to disconnect all the wiring, vacuum hoses, and fuel lines from the top of the tank.
Make sure the gas tank is mostly empty. Unplug the battery. Jack up the rear of the car. Get as much clearance as you can, because you have to get the gas tank all the way out.

Unplug the wire harness from its connector, located near the back of the tank. Set the harness in a position that it won't interfere with the tank as it is being dropped.

Remove the 8mm bolt in the support bracket holding the tank by the fuel pipe.

Remove the three 8mm bolts holding the fuel filler neck under the fuel door.

Raise the transmission jack under the gas tank. If you don't have a scissors-style transmission jack, think hard about getting one. They make themselves useful in all kinds of odd ways. If you still don't believe us, then BBK recommends using a board on a conventional floor jack. Either way, be aware that the balance point on the gas tank is actually very much on the passenger side of the tank.

Undo the three 1/2" bolts holding the retaining straps in place. Start with the strap on the driver's side, then the rear passenger side bolt, and then finally the front passenger side bolt. Before that last bolt comes off, make sure the tank is supported, because once the bolt is removed, the tank will start to drop out of place.

Slowly lower the gas tank until you can access the top of the tank. Once you can reach topside, disconnect two fuel lines using the disconnect tools, unplug the wiring for the fuel gauge sender (the driver-side) and the fuel pump (passenger-side), remove the vacuum hose that sits in a grommet on the tank, and pull the filler neck off. The filler neck can be a little tricky, and needs to be worked out of its grommet slowly, as you drop the tank at the same time.

There's the fuel pump, attached to the very top of the tank with to fuel lines leading from it.
The fuel pump is retained by a special kind of ring. This ring has to be gently rotated by tapping on it with a punch. To prevent any sparks (trust us, the LAST thing you want is sparks of any kind), use a brass or bronze punch. These aren't as common as conventional punches, but they're around. We got ours from Snap-On and paid dearly for it. Get a small one, as there's not a lot of space to work.

Once the ring is loosened, the pump pulls out. It's a little tricky to wiggle out, but it'll do it. We can't really explain how, as it's one of those things that you fiddle with for a while then all of a sudden pop! it comes out for no apparent reason. Pay attention to the proper orientation of the sock on the end of the pump; it has to fit between some baffles inside the tank and must be facing the correct direction.

Take a moment to look around the inside of the fuel tank. It's cool.

The next few steps are more easily done on the bench. Start by removing the sock (you did note which direction the sock faces?). It just pulls off. Then, undo the four 5mm bolts that hold the metal housing together. With the bracket removed, it's a simple matter to cut the two wires and disconnect the hose to the pump. The pump's out!

Original fuel pump, top, and new performance fuel pump, bottom. Yeah, they pretty much look the same.
The new pump has a slightly different configuration for its plugs; just reusing the original spade connectors will cause it to short out. You do NOT want this particular item to short out! Use the new connector that BBK provides. It just splices in normally, using normal connectors -- nothing special required. BBK provides far more wire than you'll ever need, so go ahead and hack off a lot of it. Be sure to match the wires.

Reassemble the pump and housing. Put the new sock on the same way that the old one came off. Make sure to put the new plastic disc into place on the new pump. The kit provides you with a replacement to the stock plastic disc, and it just slips around the bottom of the pump, in between the pump and the sock.

Place the assembly back into the tank. It's going to wiggle in much the same way it wiggled out -- be patient and hang in there! Once you get it in, tighten down the ring.

Lifting the tank back into the car works basically the same as taking it out. Lift it about halfway up and reattach the electrical connectors, the vacuum line, and the fuel lines. Wiggle the fuel filler neck back on -- this part kinda sucks and again requires considerable patience and determination.

Lift the tank the rest of the way and reattach the straps. Reconnect the wiring harness. Put the three 8mm bolts back onto the fuel filler neck. It may be difficult to line the holes up and get the bolts started, but with a little patience, it is possible. It's done!

We can't really tell the difference. I mean, come on, the only difference is that it pumps more fuel! But the supercharger will thank us, and if you're going the 'charged route, yours will too. One thing you might consider, though, is finding out whether you can save some money by buying the pump straight from Walbro. We don't see any compelling reason to pay BBK extra for their logo and incomplete instructions.