Replace fuel sending unit/pump

[nkmhockey]

1997 Buick LeSabre Custom – 117,000 miles

On Friday, I am going to be replacing the fuel sending unit and the fuel pump. Does anyone have any tips/suggestions?

This is the sending unit/pump I ordered from RockAuto:
SPECTRA PREMIUM Part # SP07P1H

I also ordered a new lock ring – just in case:
SPECTRA PREMIUM Part # LO01

It is going to be a big job – I know I have to drop the tank to access everything. I have already replaced the fuel pressure regulator and the fuel filter. Currently, the car stalls intermittently on downward slopes (hood down, trunk up). This behavior starts when there is around 8 gallons of gas left in the tank and makes the car un-drivable. The fuel gauge is pretty much useless, it consistently reads over ¾ full regardless of how empty the tank is.

1) Do I need any special tools for the job? I read somewhere that I need a special tool for removing the lock ring – is this true? If so, where do I get one?
2) Is a hand pump siphon sufficient for emptying the remaining gas in the tank?
3) Should the siphoned gas be re-used or disposed?
4) Is there any way I can safely clean out the inside of the tank while I have it down?
5) I have a fuel pressure gauge for testing after the job is finished – what are the standard pressures?
6) How do I check the harness code when I drop the tank?

I am 75% sure I got the correct sending unit for my vehicle. I called a GM dealer and spoke with the parts department – using the last 8 digits of my VIN he told me I would have to drop the tank and check the harness code – his system showed a unit for code HEN for around $150 and a different unit for code HER for around $180. Since both codes apply to the same part number on RockAuto, I ordered the part by process of elimination. Code CRD was not an option – I confirmed that on the phone.

Thanks in advance for any help!

[maxwedge]

A brass punch should be used to rotate the tank unit lock ring, to avoid sparks, only worry about cleaning the tank if you see dirt in there, if the tank is low don't worry about draining it, btw are you getting the whole module which includes pump and sending unit? More how to details are at autozone.com, repair guides.

[spinne1]

Originally Posted by nkmhockey

1997 Buick LeSabre Custom – 117,000 miles

On Friday, I am going to be replacing the fuel sending unit and the fuel pump. Does anyone have any tips/suggestions?

This is the sending unit/pump I ordered from RockAuto:
SPECTRA PREMIUM Part # SP07P1H

I also ordered a new lock ring – just in case:
SPECTRA PREMIUM Part # LO01

It is going to be a big job – I know I have to drop the tank to access everything. I have already replaced the fuel pressure regulator and the fuel filter. Currently, the car stalls intermittently on downward slopes (hood down, trunk up). This behavior starts when there is around 8 gallons of gas left in the tank and makes the car un-drivable. The fuel gauge is pretty much useless, it consistently reads over ¾ full regardless of how empty the tank is.

1) Do I need any special tools for the job? I read somewhere that I need a special tool for removing the lock ring – is this true? If so, where do I get one?
2) Is a hand pump siphon sufficient for emptying the remaining gas in the tank?
3) Should the siphoned gas be re-used or disposed?
4) Is there any way I can safely clean out the inside of the tank while I have it down?
5) I have a fuel pressure gauge for testing after the job is finished – what are the standard pressures?
6) How do I check the harness code when I drop the tank?

I am 75% sure I got the correct sending unit for my vehicle. I called a GM dealer and spoke with the parts department – using the last 8 digits of my VIN he told me I would have to drop the tank and check the harness code – his system showed a unit for code HEN for around $150 and a different unit for code HER for around $180. Since both codes apply to the same part number on RockAuto, I ordered the part by process of elimination. Code CRD was not an option – I confirmed that on the phone.

Thanks in advance for any help!

Yes, it is a huge job. If your fasteners are in good shape under the car it won't be so bad. Mine broke when removing and had to be ground off with a hand grinder (about an hour per bolt for two bolts.) Once the straps are off you can get the gas out a little easier than siphoning if you use a good floor jack and a large piece of wood under the tank (get the car on four jack stands and good and high.) Once free from the rubber inlet pipes and tubes, put a large plastic flat new container under the open spout on the tank and lean the whole tank that way a bit to pour gas. Empty the container into a gas can(s) and repeat until empty. You could use a hand siphon but they don't always work that well. If you do use one use it after you remove the rubber inlet pipes and tubes. Otherwise your siphon tube won't likely make it into the tank. (Make sure your tank is not basically full or else you will have some trouble with spillage when removing the fill/inlet tubes.) If it is full drive the car until less gas is in the tank preferably.

Special tools? Not that I can think of. If you are lucky your gas lines will easily separate from the original sending unit. I was not so lucky. I had to buy repair kits for both lines. I also had to replace my entire gas tank because of broken plastic inside the tank and rust issues on the outside.

The siphoned gas is fine to use as long as it is free of sediment and is not contaminated during the process and as long as your original tank is not sediment filled. If dirty, you could filter it somehow but I would save it for your lawnmower/weedeater if there is any question (and only if generally clean looking.) If it looks perfectly clean, I'd reuse it and simply replace my fuel filter after a little while to get the particles out of the loop.

Clean the tank? Some ideas here:
http://www.hotrodders.com/forum/clea...nk-117561.html

Fuel pressures? I don't know but generally 40-50 psi is normal. Check your specific service manual if you have one.

What is a harness code?

[Smith1000]

My wife's Lesabre would stall on downward slopes intermittently and it turned out to be the MAF sensor. I would use MAF sensor spray cleaner on it and it would stop the stalling immediately. About 4 or 5 months later, it would do it again and I would clean it again. It would only happen on downward slope, usually when braking, or coming to a stop.

Maybe the wiring to the existing fuel pump should be checked first to ensure the grounds are good, etc.

I would spray down the strap retain threads in advance with some solvent. I ran into problems at could not get one of the bolts loose. it broke and spun. There is no easy way to hold it to keep it from spinning. Also, I recall having problems with the fill hose. The original clamps were difficult to get off. Replacing the sending unit and fuel pump is fairly easy once the tank is down.

[Rasp]

I also had replaced my old 89 Lesabres fuel pump (may she rest in peace). I also had the problem where the bolts would not turn out because the fastener was broken on both straps.

They basically get rusted out over the years and become almost impossible to turn out.

My fuel lines also needed repair kits as well. They are also an issue on certain years of lesabres. They rust out and become a real pain to take off. I ended up just cutting them and repairing with a kit.

The job itself if everything comes off easy is really straight forward and not to bad but when you work with a corroded underbelly you should be ready to have a few issues.

If you take your time and have patience and know that you will more than likely have a few issues, then you'll get through this.

BTW your not the only one who had to do this. so if you do have further problems send a message on the boards.

[nkmhockey]

I have been driving the car (very carefully) the past few days to try to get the fuel level as low as possible. I would guess by Friday I will still have about 3-5 gallons in the tank – should I still drain the tank or is that level low enough to work with? Is it recommended to drain the tank regardless of the level to get any sediment out?

I am going to have my Dad help me with the project, so I will have an extra pair of hands. Less than 12 months ago I had a mechanic drop the tank and replace only the fuel pump (re-used same sending unit) – so I am hoping that everything should still be relatively easy to remove since he did the grunt work the first time.

I have already cleaned the MAF several times with MAF-cleaner without any results. The stalling only occurs when the gas tank drops below half-full, so I am fairly certain it is an in-tank issue. The car has never stalled with the gas level above half-full.

I am going to spray all of the fasteners I can get to with penetrating oil on Thursday night. The fuel filter has already been replaced once – I broke the fuel line and had to use a repair kit. Should I replace the fuel filter again?

I live in the salt belt, so rust is definitely a concern. My mechanic did mention that there is one section of steel brake line that is fairly rusted near the rear passenger tire – is the line anywhere near the fuel tank? Do I need to drop any exhaust parts out of the way?

I have 2 jack stands, a hydraulic jack, and the tire jack that came with the car, is that enough for this job?

Thanks for all the suggestions; I greatly appreciate all the help!

[happydog500]

When I did mine, the "big job" part was thinking about it before hand. Once I got into it, I was surprised how easy it was.
I had a friend help, we did it with a full tank of gas.

It is easy to do. Straps came off easy.

One thing I remember is, we had to lower the tank to get to the wires going to the top of the tank. You can't lower it very far because the wires where short.

Be ready to hold the tank and reach up and unplug them. If I remember right, there was another set of wires or two that I didn't expect.

For me, the screen on the sending unit was hard to get on the last little bit. We pounded and pounded but never got it on all the way to the end. I was on good tho.

If you can, look to see if yours goes to the end and let me know, please.

Thank you,
Chris.

Chris.

[spinne1]

Originally Posted by nkmhockey

I have 2 jack stands, a hydraulic jack, and the tire jack that came with the car, is that enough for this job?

I think you should have 4 jack stands or else it will be much more difficult. You will have better luck if the whole car is basically level and high off the ground. You generally won't need the tire jack that came with the car. Just a good floor jack. As for draining all the fuel out, it will be very heavy still if it has 3-5 gallons of gas in it. Therefore to make it easy get it out.

[nkmhockey]

Well, the job was a success! It was extremely difficult, but the stalling is completely fixed, the fuel gauge works, and everything appears to be working properly.

The job took two people the entire day. I have no idea how my mechanic did this job without having any problems – the rust was unbelievable.

The strap bolts snapped the stud off on the frame of the car, making them impossible to remove, both were spinning freely after just a few turns. We were forced to use a hacksaw to cut the rusted straps in half. Then, we were able to maneuver the tank out with the floor jack. The parking brake cable was a real problem – as was the rear passenger brake line. The brake line was extremely rusted could easily have been crushed with the side of the tank.

We had to saw the strap bolts off to get them off of the frame of the car. The two fuel filler hoses were melted together, so they were cut with a knife. The tank had very little gas left – it looked clean, so we did not need to dump any of the remaining gas out.

Overall, the job was far more costly than anticipated. The tank straps needed to be replaced, but neither NAPA, Pep Boys, Advance, nor AutoZone carried them in stock (around $25 for them to arrive on Monday). The fuel filler hoses are a dealer item – I could find similar hoses in size and length, but they are simply too hard to bend into the correct shape.

The local GM dealer wanted $115.00 JUST for the fuel filler hoses – I told the guy he was out of his mind… Those hoses cannot cost more than $20 to manufacture. He cut me a break; I got the hoses, 2 bolts, and both straps for around $105. $40 for both straps, $65 for the hoses, and he gave me the bolts for free out of pity.

When we removed the old sending unit, we found the problem. The pickup screen had fallen off of the pump and was floating around inside the tank. We cleaned everything up, dropped in the new sending unit/pump assembly, and raised the tank back up into position. My Father had to jury-rig the bolts onto the frame – we mounted them upside down using nuts and lock washers. The new straps were difficult to work with; they just were not an exact fit and had to be bent into place.

Once everything was back together, we let the pump pressurize the system. It leaked immediately. Turns out, a rubber hose running from the sending unit to the fuel filter had a bad fitting. $20 at NAPA.

I hope this helps someone in the future. The job was well worth it, and necessary, but if you live in the salt belt I highly recommend leaving any fuel tank work to a mechanic. I am not even going to post the total cost of the project, it is too depressing….

[happydog500]

Just out of curiosity, I see you can get just the pump, or the whole assembly for just a little more. Did you just get the pump, or the whole assembly?
I replaced the pump a year and 4 months a go and it's going out again.
Chris.

[Earl-R]

I Replaced my father-in-laws sending unit yesterday. Now instead of only going to1/4 tank and stopping the new unit will read empty but when full it reads about 1/3. Bad unit? Someone I know mentioned recalibrating to the unit to match for the cars computer (ECM - BCM)Any help would be helpful.Thanks in advance.Earl

[Smith1000]

I'd say the sending unit is the wrong one and likely has a range of 0 to 80 ohms. This was common in GM vehicles for a long time. In my 97 Lesabre, the sending unit ohm range is 0-240, so 1/3 tank should read 240 X .3333, which is 79.99 ohms (80 ohms). If the max resistance on the sending unit you installed happened to be 80 ohms (reading when full), your gauge will read 1/3 tank when full. This is a possibility for what is wrong.

[happydog500]

Check the code on the old one, compare it to the one you got.