Rover Tech: Discovery 1 GM Fuel Pump Swap

NB: This is an incomplete post from December 2016 on the subject of replacing the core of fuel pumps for 1980s-90s Land Rovers. I never finished it, but I’m publishing it in March 2018 for the benefit of a friend in need of the information. I’ll get to it eventually.

If there’s one thing I like doing with my truck, it’s making it more field servicable. The great thing about 90s-era Land Rovers is that they actually have a lot of parts crossover with other European, and even American, cars. One of the classic instances of this is swapping a fuel pump from a General Motors vehicle into a Discovery 1 or Range Rover Classic.

I did this on the side of the road in Upstate New York back in June 2016, but it seems like my half-assed trail fix backfired, as now in a deep and dark December, I find my truck again stranded, this time in my driveway.

Since there’s a lot of forum posts about how to fix this, but no really thorough explanation for those of us who are both visual and anal-retentive, I’ve written this heavily-illustrated article to help you, oh gentle reader, too get your Land Rover on the road.

This is a somewhat simple fix, all in. You can cobble it together, as I did, and do fine for a while. But in the heat of the moment on a warm summer’s day in a gas station forecourt, I missed several steps, and there’s some things I wish I’d done differently.

The details henceforth apply to a 1994 Discovery 1 with a North American-spec 3.9 litre Rover V8. They “should” cross over to V8 Range Rover Classics after 1989, and continue to cover all Discovery 1 models through the run-out year of 1999. However, I make no guarantees. Later Discovery 1 trucks had some variations in their fuel systems, most notably the addition of AEL (Advanced Evaporation Loss) systems in the 1997 model year, and the 4.0 litre GEMS engine may have some different requirements to the earlier 14CUX ignition system. As I’ve only ever owned 14CUX trucks, I’m not sure there. There’s a pretty good chance that these instructions largely or totally apply to these other applications, but I make no guarantees, and if you blow up your truck using these instructions, that’s on you.

Right, onward.

When I say "remove everything from the back," this is how not-fun that is to do on a roadtrip.
When I say “remove everything from the back,” this is how not-fun that is to do on a roadtrip.

The fuel pump is located in the fuel tank, and can be accessed through a hatch in the rear floor on all Discovery 1s and Range Rover Classics after 1989. To get to this hatch, remove everything from the back of the vehicle, pull up the rear carpeting, and you will find a flap cut into the rubber padding beneath in the rear cargo area floor. Flip it over and you’ll see a round hatch about twelve inches around. Undo the six screws and set it aside. Do not lose the screws like I did.

There’s three things to disconnect here, which are both electric and fuel. Remember, these things do not go well together. The electric multiplug comes off by pushing the tab in the side and sliding it off. There’s two fittings holding the feed and return lines that go from the pump to the engine. Depending on where you live, when/if this was last done, and your lot in life, these may be very, very seized. A liberal application of your favourite penetrating liquid (I’m a PB Blaster man myself) and high-quality profanity, combined with the patience of a saint, should undo these. Keep calm, if these break you’re kinda pretty much completely screwed.

Now that you’ve undone these three connections, the good thing to do would be to vacuum the indentation around the fuel pump port in the tank so that you don’t get all the dirt and crap in the tank. This is possible to varying degrees depending on situation, however, so if you’re really stuck just do the best you can. Then undo the giant ring around the fuel pump hole, and lift it away. The pump now sits before you, awaiting its careful removal from the hole in the tank, an exercise to be undertaken with the greatest of care to avoid damaging the float for the level sensor.

Unless you’re a better man or woman than I, you will spill fuel in your cargo area. Fortunately you’ve got the carpet all tucked away somewhere nice, and you can just try and sop up as much as you can.

The liberated pump.
—”Mr Fuel Pump, are you free?” —”I’m free!”

You have now liberated the fuel pump, and it’s time to really dig in. Go somewhere relatively clean with it and it’s time to disassemble.

The pump itself is contained in the lower, enclosed half of the assembly. To detach this, carefully prise the four clips holding it in, taking the utmost of care to not break them. Doing this second exercise in December, with an outdoor temperature of 15 Fahrenheit, I decided that it would be prudent to bring the assembly inside to warm up a bit to help prevent brittleness issues. (Remember, direct heat is not a way to assuage this, considering the circumstance.)

You should now see the metal cylindrical pump exposed, with two electrical wires attaching it to the top of the assembly and a plastic corrugated hose connecting the pump’s output to the outlet for the feed line at the top of the assembly. The original pump, at least on my truck, has a flanged barb on the end of the output outlet, which nicely nests into this hose.

When keeping in mind that Land Rover did not really intend for this assembly to be a user-serviceable part, this hose has a very symbiotic relationship with its original host pump, but it is both very difficult and somewhat impractical to reuse it. The two replacement pumps I’ve had so far (more on that below) did not have these dramatic barbs on the outlet, which impacts the ability of this hose to seal to the new pump. When I had my original trailside repair, I kind of picked it off with an etching chisel and needlenose pliers, and later reattached it by squeezing it shut with a zip tie. This was functional but not ideal, so let’s do it proper.

Right, now you’ve got the actual pump itself free, let’s take a look.

I’m looking at three pumps here: (1) the original Land Rover part, which may or may not have been there for twenty-two years; (2) the latest purchase, an ACDelco EP241; and (3) the interim device, a Delphi FE0114 that I purchased at a NAPA on site.

Here is where I figured some stuff out after the fact. Apparently the 14CUX (1994-5 D1, possibly RRC 1989ish-1995) and GEMS (1996-9) trucks could use different spec pumps. Going back to vintage resources, the venerable Discoweb parts number resource, likely last updated some time during the second Bush administration, supplies different part numbers that I’ve extrapolated as follows:

14CUX/3.9
AC Delco EP-241

GEMS/4.0
Airtex E3270
Delphi FE0114

What’s the difference?

(WHAT THE $@%# IS THE DIFFERENCE?)

After replacing the part, I’ve found that the EP-241 does, in fact, seem to run better than the FE0114. It is quieter, and the truck seems to have slightly better performance. This may be in my head.