Write-Up: Fuel Pump/Tank Sending Unit Replacement

Rickw wrote:

Brian,
What year is your car and is it Supercharged.?
This makes a difference on pump selection as well as installation procedure.

You need to fill out your signature so we can better help you.
just look at the FAQ's for instructions on how to fill out that info also.

Definitely!

I have a writeup I haven't done yet, but here are a few photos of a '97 supercharged/VIN-1/MU35 fuel pump module...

Mine also had slop in the shaft and the contacts were no longer touching the rheostat. I added a bit of preload by bending the shaft and it appears to work!

Mikel wrote:

Mine also had slop in the shaft and the contacts were no longer touching the rheostat. I added a bit of preload by bending the shaft and it appears to work!

Alright, I got the pump and I'm going to install it here in about 30 minutes. Came with a new harness as well.

One thing that seems different is that it has a rubber sleeve instead of that flimsy rubber gasket I got with the last pump. This thing won't distort or move out of it's place. If I'm wrong thinking the other pump didn't have this, I'll update.

I don't think we have a fuel pump write-up yet, if you should happen to take some pics...

Well I've taken pictures up to this point.

Just realized the electrical connections are different. Hmmm..

EDIT: According to them the connectors are different and are suppose to be replaced. Off to do a small bit of wiring.

I got it installed. Couldn't use the rubber grommet. Hole isn't big enough.

It does work fine and is whine free, but my guess gauge is showing 1/4 more than it was showing with the last pump. Should I go fill up and see how much it holds to see if the new one is inaccurate?

manofmany wrote:

I got it installed. Couldn't use the rubber grommet. Hole isn't big enough.

It does work fine and is whine free, but my guess gauge is showing 1/4 more than it was showing with the last pump. Should I go fill up and see how much it holds to see if the new one is inaccurate?

"Guess" gauge.


LOL!

That's funny.

LOL that was not intentional but definitely is fitting.

It's definitely off. I'm going to try switching out the float with the old one after dinner.

Update:

I changed out the float and initially got the same reading. Began driving home and the level slowly began dropping after going WOT. It dropped to a notch over half. Went to the gas station and it clicked off at 9.4 gallons. Seems like it may be accurate.

manofmany wrote:

Update:

I changed out the float and initially got the same reading. Began driving home and the level slowly began dropping after going WOT. It dropped to a notch over half. Went to the gas station and it clicked off at 9.4 gallons. Seems like it may be accurate.

Have you had a chance to refuel & check the accuracy? From my own experience, both senders are probably fine, it's just the slight variation between units and it takes a little bending of the float arm to fine-tune it...

Eldo wrote:

manofmany wrote:

Update:

I changed out the float and initially got the same reading. Began driving home and the level slowly began dropping after going WOT. It dropped to a notch over half. Went to the gas station and it clicked off at 9.4 gallons. Seems like it may be accurate.

Have you had a chance to refuel & check the accuracy? From my own experience, both senders are probably fine, it's just the slight variation between units and it takes a little bending of the float arm to fine-tune it...

I've put 600 miles on the car since the install. As I mentioned, I did change out the float with the old one. It's 100% accurate according to my calculations.

I did order a new rubber seal which is going on possibly today. Otherwise, doesn't seem like a bad deal for $58!

EDIT: I do have several pictures that I will try to get together one day when I've got time for a write-up.

Here we go. Not sure if you can consider this a write-up, but if it's helps somebody, I'm happy!

Tools Needed:

7mm socket
Flat head screwdriver
Large pry bar and hammer (optional)
Wire stripper

Parts Needed:

Fuel Pump (Pump in the pictures purchased from Ebay seller radiatorclassic for $58+shipping for a 1997 3800 SC)
New locking ring (optional) Part #25691383
New pump seal (Necessary) Part #25028682

Depending on the pump you get, you may or may not have to rewire a new plug. I had to. Also, some pumps come with a new seal and some don't. The seal that came with my last Airtex pump was too flimsy and would deform as the locking ring was locked into place. I STRONGLY advise purchasing an OE seal using the part number above. It's $5 from Rockauto or about $9 from a dealer.

The locking ring should be replaced if it's in terrible condition. My OE ring 2 years ago was not reusable. It's just over $2 on Rockauto using the above part number.


New Pump. Notice the black rubber grommet. Unfortunately, this will not work with our tank and will need to be removed. I would prefer something such as this to the standard rubber o-ring.




Red Arrow marks the location of the fuel pump access panel. Passenger side front trunk area.




Here you can see the access panel. It is secured with 5 7mm screws. After loosening them, it may be necessary to use a flat head screwdriver to separate the panel from the trunk.




The old pump. The red arrow points to a blue plastic piece that needs to be removed so you can remove the electric plug. It should pull right up. You may be able to press down on the pump and get the ring off by hand. If not, first try pushing with a flat head screwdriver. In my case, I had to use a bar and a hammer to knock it loose. Use caution if this needs to be done.




Here you can see the locking ring dislodged and two fuel lines still attached. I personally remove the gas cap and under the hood and beauty cover, there is a shrader valve on the front fuel rail. I use a paper towel and small screwdriver to press that in to relieve fuel pressure. One pressure is relieved, you can procede to squeeze the quick-disconnects and remove the fuel lines. Wipe up any spillage.




Old pump removed. You can see the slight differences. In my case, I had to switch floats. The float is long metal arm with the plastic float. If you place your finger in between the 2 clips securing it, you should be able to pull it right out. It goes back on the same way. Just press it on.




Locking ring




Here you can see the difference in the two plugs.




Rewired. Very simple. There are two thicker wires and two thinner wires. Simply color-match and rewire them. If your pump comes with a new plug, it should include everything you need. Trim back the sheathing if need be and replace.




Installation is reverse of removal.

manofmany wrote:

Tools Needed:

Fuel Pump (Pump in the pictures purchased from Ebay seller radiatorclassic for $58+shipping for a 1997 3800 SC)

Whats is the brand/model # of that pump?

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.