I am in the process of replacing the fuel sending unit on my 1998 Land Rover Discovery. When I removed the old one I realized that the plastic retaining ring that is the top of the tank was broken. After paying an arm and a leg Country West was kind enough to send me a new ring. This ring is not sold as a seprate piece, but with the gas tank. Now I can't get the damn thing tightend all the way down.

Does anyone out there have any suggestions?

 

Yeah, its a PIA, it only goes in one way, I forget which way is up you will need to trial and error.

 

Land Rover Discovery I Fuel Parts Available from RoversNorth.com
Land Rover Discovery I Fuel Pump Parts Available from RoversNorth.com

LAND ROVER PARTS - RETAINER RING - FUEL SENDER

I wish you had asked about fuel pump assemblies prior to spending an arm and a leg for a 5 dollar part. I always check with Rovers North FIRST, even if I do not buy from them, they have the best illustrated parts breakdowns for each and every system in our aging Discoveries. They show each individual part, their relationship to the other parts and their prices, which for new Rover parts, Rovers North is hard to beat. They deal only in Rover Parts, they have practically everything in stock, at a very fair price, all of their staff own and drive Rovers of practically every type and they will take the time to answer any question you may have.

Whoever told you that the locking ring is not available as a separate part was flatout wrong or they lied to you.

I have an early 97 which is the pre-AEL version. A complete fuel pump assembly in the ProLine brand which is a direct drop-in perfect fit replacement is right at 100 bucks, the retaining ring is a whopping 4.99. I referenced 3 of their webpages showing the overall system right down to the individual part.

On mine, the top of the assembly had a nasty crack which necessitated the replacement of the entire assembly, I also bought the retaining ring. At their prices, I cannot complain. I also bought this seal:
LAND ROVER PARTS - SEAL - FUEL PUMP-TANK ADVANCED EVAPORATIVE LOSS

As far as getting it back together, I learned that the easiest way was to put the new seal in place on the tank lip, I used a light coating of vaseline on the interior surface of the seal, eased the replacement pump assembly into place being careful to keep the seal in the correct place. With the new pump seated, you can ease the locking ring down over the top of the pump assembly and compress the ring straight down as you start to rotate the locking ring on the threads. You should be able to continue threading the ring into place, you may need to use both hands and carefully rotate it.

You can also carefully tap the ring with the tip of a flat bladed screwdriver held against the side of the ring tapping with a hammer to securely tighten the ring in place.

The real key is putting the seal in place first, fully seating the pump assembly, then tightening the ring. I first tried with the seal around the pump assembly and trying to put the pump assembly into place but that method does not work as easily as what I describe above.

Patience and finesse will conquer it. Otherwise, you will struggle with it and not be able to get it together fully. It is imperative you get it fully seated and sealed as the pressure is in the 36-40 PSI range and a gap is a bad thing, as fuel will spray everywhere.