Write-Up: Fuel Pump/Tank Sending Unit Replacement

Honestly, I couldn't tell you. There were no markings on it. Aside from switching out the floats, it's working great.

Can someone on the forum comment on the fuel sender unit for the 1995 S/C Riv?

My fuel gage moves down very slowly to reading a little more 3/4 of a tank when, based on known MPG and miles traveled, the tank is actually about 40% fuel.

I suspect that the sending unit is the problem and I would like to replace it.

To that end,

1. Can someone tell me if there is access to the fuel pump throught the trunk as noted for the 1998 and 1999 models as referenced elsewhere in this forum?

2. Any recommendations on where to get a replacement fuel sender unit and about how much one might cost?

Thanks for the help!

Love my Riv!

See this write-up for Series I SC. It should answer your questions:

https://rivperformance.editboard.com/t2918-write-up-walbro-255-lph-fuel-pump-series-i

has anyone come across a repair for replacing rusted away tank lock ring tabs?

mike97 wrote:

has anyone come across a repair for replacing rusted away tank lock ring tabs?

ask BigRay.He found a way.

I've been searching for a tank to replace mine with lock tab rusted out. I have found some tanks along with some very conflicting and confusing info.
all I wanted to know was which years and model used the same tank as my SC-97, not tough, you'd think. I called all four local dealers, 10+ salvage yards,
parts places and GM buick customer services. what I got was a combination of more than eight different answers- and a slight headache. take a look.
97 - riv only
97 - SC riv
97 - 99 riv
95 - 99 riv
97 - 99 riv, aurora
97 - riv, aurora, park ave
97 - 05 park ave
97 - 05 park ave ultra
I won't mention the pontiac's. I would stick to SC- 97 but there rare here (non rust) or long distance.
can anyone help me out with some first hand info or know where I can get it.

The 97 Riviera, Park Ave., and Aurora used the same fuel tank.

Replacing the tank is a big job. A friend of mine used 4 stainless self tapping screws and washers to hold the pump ring down. he used some sealer, and screwed them into the plastic tank.

LARRY70GS wrote:

Replacing the tank is a big job. A friend of mine used 4 stainless self tapping screws and washers to hold the pump ring down. he used some sealer, and screwed them into the plastic tank.

great idea. What's the worst you can do - ruin the tank?

deekster_caddy wrote:

LARRY70GS wrote:

Replacing the tank is a big job. A friend of mine used 4 stainless self tapping screws and washers to hold the pump ring down. he used some sealer, and screwed them into the plastic tank.

great idea. What's the worst you can do - ruin the tank?

Worked like a charm for my friend. In fact he sold the car to a member on this board. Forget who it is. Car was from Monroe, CT, and was black. I want to say it is DEMonte1997 , but I'm not sure.

thanks for the response but according to my gmp service manual
the riv have a different tanks with .6 gallons more than aurora
riv - 76 liter
olds - 73.4 liter

I just want a spare tank on hand to replace mine if poking holes goes badly !

LARRY70GS wrote:

deekster_caddy wrote:

LARRY70GS wrote:

Replacing the tank is a big job. A friend of mine used 4 stainless self tapping screws and washers to hold the pump ring down. he used some sealer, and screwed them into the plastic tank.

great idea. What's the worst you can do - ruin the tank?

Worked like a charm for my friend. In fact he sold the car to a member on this board. Forget who it is. Car was from Monroe, CT, and was black. I want to say it is DEMonte1997 , but I'm not sure.

You are correct, Larry. I bought that car from Bob and after a few years sold it to DeMonte1997. Bob did the repair and it never leaked.

71gsx455-4spd wrote:

LARRY70GS wrote:

deekster_caddy wrote:

LARRY70GS wrote:

Replacing the tank is a big job. A friend of mine used 4 stainless self tapping screws and washers to hold the pump ring down. he used some sealer, and screwed them into the plastic tank.

great idea. What's the worst you can do - ruin the tank?

Worked like a charm for my friend. In fact he sold the car to a member on this board. Forget who it is. Car was from Monroe, CT, and was black. I want to say it is DEMonte1997 , but I'm not sure.

You are correct, Larry. I bought that car from Bob and after a few years sold it to DeMonte1997. Bob did the repair and it never leaked.

Maybe we can get DeMonte1997 to unbolt the inspection cover and take a picture of the repair. A picture is worth a thousand words, and at least some of us will be faced with this fuel tank problem at some point.

I PM'd DeMonte1997 and asked him to look in here.

Taking the inspection cover off now...

Some info on the fuel tank (pic of tank removed) and capacity findings can be found here:

https://rivperformance.editboard.com/t1760-the-gas-tank-fuel-capacity

On second thought...

I'm not sure how the inspection cover is usually configured. This one has 5 bolts. Those are 7mm and come out easy enough. However, it appears the cover itself was RTV'd to the trunk base to form a gasket. It doesn't want to budge. Is this typical? It could be double sided tape... doesn't seem like a normal rubber gasket judging by how it does not give no matter how hard I pull on it.

If someone can chime in in the next hour or so, that would be fantastic. I'll need to button this sucker back up in a bit but I'd like to try and make a final attempt at getting the pics prior.

The cover should not be sealed to the floor. A flat screw driver should peel it right up. There are some pics on page 6.

I think mine had some soft sealer, but it came off. Just have to pry a bit.

I'm not sure what went on with this cover but someone thought it would be prudent to goop it to the trunk. :/ The cover looks like it was pretty warped and then somewhat hammered it flat. Still looks screwed up to me. That might be why it was RTV'd. Not sure if that is necessary..

In short, it would take a large effort to get this damn thing off.

I've played with soft sealer on the inner door insulation and that wasn't any trouble. This stuff does not want to budge.

Oh Well, thanks for trying.

I don't own a Riviera, but I've been considering purchasing one. Is it as simple as lifting up the carpeting in the trunk and looking around the fuel pump to see if that ring is rusted out, or is it more hidden?

Just trying to educate myself on model specific things to watch out for when I'm looking them over.

Yoss wrote:

I don't own a Riviera, but I've been considering purchasing one. Is it as simple as lifting up the carpeting in the trunk and looking around the fuel pump to see if that ring is rusted out, or is it more hidden?

Just trying to educate myself on model specific things to watch out for when I'm looking them over.

Yes. The carpet and the wooden spare tire "cap" has to come out in order to see it. AND, there is an access cap with about eight 7mm screws that also has to be removed.
As for the gas tank, it's not so easy to replace. They damn near built the entire rear suspension around the tank

That's what I hear. I may try to do this as a project now, though I've never 'dropped' a rear suspension before. My buddy found a few gas tanks, but doesn't have the time to give me on doing the job. I'm sure there's a youtube video somewhere probably, and he'll help me to the extent that he can. I figure it's worth a shot, as I love the car. There's nothing too complicated he says, just the probability of alot of rusted bolts - nothing a hacksaw and torch can't handle. Let's see... a torch and a gas tank - doesn't sound like a good combination!

Thanks to all for your input.

Mike

taking a dinner break now..

My lock ring is rusted bad and will not budge. I am trying to tap it with a screw driver and hammer but have only gotten it to move maybe 1mm. It's on there REAL tight and not going anywhere fast.

I just did some searching and there is a tool - a fuel sender spanner wrench J 39765 to get the ring off?

Do i need that or is mine stuck on there unusually well?

Bout to finish dinner and go back out to beat the crap out this thing.