Fuel Sending Unit

[jss06c6]

Well, the fuel gauge seemed to get stuck at full. Finally came off full after about 60 miles! Don't know if it got stuck or ethanol in the fuel is beginning to have an impact.

Fuel pumps are original, but have no issues. Does anyone sell only the sending unit if it is indeed faulty?

Thanks all!

Steve

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[lfalzarano]

I’ve experience the same thing even when it was a youngster in the 90’s. I don’t think it is abnormal. Be advised it goes to empty allot quicker, so don’t hesitate to fill it up sooner... [emoji41]


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[Ccmano]

Search AC/Delco FLS1102, they are out there including on eBay.
H
:cheers:

[jss06c6]

Thanks Hans!

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[Ccmano]

Thanks Hans!

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No worries, shop carefully, prices vary by over $100.
H
:cheers:

[jss06c6]

The ones I find are complete with fuel pump.. no-one sells only the sending unit?

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[jss06c6]

$373.07 on Amazon. Coming from Big3Direct...

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[jss06c6]

Just saw poor ratings on this supplier!

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[A26B]

Sending unit not sold without pumps The complete sending unit with pumps will soon be discontinued and NLA.
I am collecting used sender/pump assembly cores with the intent to rebuild complete units. If anyone has used, dead ones please contact me.


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[jss06c6]

Thanks Jerry. I'll order from Summit and send you mine if it is indeed faulty..

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[Ccmano]

The standard C4 version is sold without the pumps. I wonder if just the actual sending unit part could be transferred?
H
:cheers:

[Wigert]

Hey

I have a similar problem and have been planning to try to repair it. I found the link below a while back.

https://www.corvetteforum.com/forums/c4-tech-performance/1574491-fuel-gauge-sending-unit-repair-tech-article.html

Anyone here tried it?

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[jss06c6]

Ended up ordering from Jegs. In stock and no tax or shipping. Still cost $380!

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[jss06c6]

Hey

I have a similar problem and have been planning to try to repair it. I found the link below a while back.

https://www.corvetteforum.com/forums/c4-tech-performance/1574491-fuel-gauge-sending-unit-repair-tech-article.html

Anyone here tried it?

Skickat från min GEM-701L via Tapatalk
I'll certainly try it on mine!

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[jss06c6]

Here's the quick sequence..

1. removed FP1 fuse from fuse block
7300
2. started engine, let it run a bit to depressurize the system
3. disconnected battery
4. removed fuel fill cover (4 torx screws)
5. removed rubber fuel dam and disconnected fuel drain line
7301
6. removed white keeper key in plug
7303
7. disconnected plug
8. removed fuel supply, return and vent hoses (took pliers and gently rotated hoses on pipe nipples to allow me to remove them
7302
9. removed 10 mm bolts, being careful to capture the o-rings on each
10. carefully lifted the pump assembly, rotated it 90 degrees CCW and carefully worked it out of the tank (had to work the fuel hoses a bit to clear the lip of the tank
7304
11. removed the gasket (carefully to prevent any debris in the tank
12. was surprised to see a tray in the bottom of the tank where the float rests in an empty tank (it was yellow plastic)
13. taped the tank opening closed with duct tape to prevent contamination and debris from entering the tank

Once on the bench, I clipped one lead of my meter to the purple wiper lead on then sending unit and the other lead to ground. Tank empty read about 0.5 ohms, Tank full initially read 95 ohms. There was nothing erratic during a sweep from tank empty to tank full. I worked it multiple times slowly, then rapidly and the tank full reading moved to 105 ohms and was stable. I guess I might have had a little debris in the potentiometer. I could also see interference between the float rod and the fuel hose clamp to the top fuel pump. Don't believe this would cause a problem, but should not be hitting it regardless.

The socks looked pretty good for 27 years old. Tank was clean as well. My new pump assembly is backordered from Jegs.. Should ship on April 19th.. I'll compare the new to the old and install the new one. Not sure what I'll do quite yet with the old one since it still appears to be working..

So, at this point, I don't know what caused my fuel gauge to stick to essentially full for the first 60 miles.. Guess there was a small amount of debris, but likely would have cleared itself after a few more miles of driving.. Oh well, good to replace the pumps and sending unit as preventive maintenance.. I'll attach some photos for entertainment..

[Dynomite]

Here's the quick sequence of removing the Fuel Pump......

1. removed FP1 fuse from fuse block

https://cimg5.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x500-1/80-fuel_1_7b16a56ffacc6701990b8e52a0f5f9f6253ac5d4.pn g

2. started engine, let it run a bit to depressurize the system
3. disconnected battery
4. removed fuel fill cover (4 torx screws)
5. removed rubber fuel dam and disconnected fuel drain line

https://cimg8.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x500-1/80-fuel_2_435b812a823809fa83fe73f49f9293ba99d08a69.pn g

6. removed white keeper key in plug

https://cimg2.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x500-1/80-fuel_4_25e605e0d516057498f5797269d7af9dcf247eb2.pn g

7. disconnected plug
8. removed fuel supply, return and vent hoses (took pliers and gently rotated hoses on pipe nipples to allow me to remove them

https://cimg1.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/400x400-1/80-fuel_3_7e64a2ec141916a52717ad034cac1631c183c4e2.pn g

9. removed 10 mm bolts, being careful to capture the o-rings on each
10. carefully lifted the pump assembly, rotated it 90 degrees CCW and carefully worked it out of the tank (had to work the fuel hoses a bit to clear the lip of the tank

https://cimg3.ibsrv.net/gimg/www.corvetteforum.com-vbulletin/600x500-1/80-fuel_5_7525c5fa2d4da0769c401fd2a918844c2fe28cd0.pn g

11. removed the gasket (carefully to prevent any debris in the tank
12. was surprised to see a tray in the bottom of the tank where the float rests in an empty tank (it was yellow plastic)
13. taped the tank opening closed with duct tape to prevent contamination and debris from entering the tank

Once on the bench, I clipped one lead of my meter to the purple wiper lead on then sending unit and the other lead to ground. Tank empty read about 0.5 ohms, Tank full initially read 95 ohms. There was nothing erratic during a sweep from tank empty to tank full. I worked it multiple times slowly, then rapidly and the tank full reading moved to 105 ohms and was stable. I guess I might have had a little debris in the potentiometer. I could also see interference between the float rod and the fuel hose clamp to the top fuel pump. Don't believe this would cause a problem, but should not be hitting it regardless.

The socks looked pretty good for 27 years old. Tank was clean as well. My new pump assembly is backordered from Jegs.. Should ship on April 19th.. I'll compare the new to the old and install the new one. Not sure what I'll do quite yet with the old one since it still appears to be working..

So, at this point, I don't know what caused my fuel gauge to stick to essentially full for the first 60 miles.. Guess there was a small amount of debris, but likely would have cleared itself after a few more miles of driving.. Oh well, good to replace the pumps and sending unit as preventive maintenance.. I'll attach some photos for entertainment..

Your post is linked in Solutions (6th Post).......Step by Step with fastener sizes is always a great reference :thumbsup:

You are welcome to copy the photos back into your original post above as you like :handshak:

[jss06c6]

I'll do that.. thanks very much for the help!!

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[jss06c6]

Well, just received this from Jegs!

"Thank you for your order. Part ~065-FLS1102 is discontinued. AC Delco has not offered an replacement item. Your backorder for this item has been canceled. If you have any questions please call us at 1-800-345-4545 and speak with a tech sales representative. We apologize for the inconvenience."

Looks like if I can't source another one from someone who still has some stock, I'll be replacing the pumps in this unit and taking the sending unit apart to verify it's in the best condition possible..

Didn't Walbro make pumps we can substitute?

[JFFerner]

Before spending hundreds of dollars you may want to try using a Chevron product called Techron concentrate. It's available at Advanced Auto,Walmart, etc. 10 ounces for about $5. Dump in it into an almost empty gas tank, add up to 15 gallons of gas and drive. By the time you need to fill up again, your sending unit will probably work. This stuff works great. John Porter turned me onto it 5+ years ago.

[9T1 Red ZR1]

Hello,
I just ordered FLS1102 from carid.com for $300.43. It is the complete unit with two pumps, fuel sender and float. It came to my house in PA in two days. They still show two in stock if you are interested. I haven't installed mine yet, I am in the middle of other projects right now.


Bill

[A26B]

Hello,
I just ordered FLS1102 from carid.com for $300.43. It is the complete unit with two pumps, fuel sender and float. It came to my house in PA in two days. They still show two in stock if you are interested. I haven't installed mine yet, I am in the middle of other projects right now.


Bill

Check the socks, both of them. The last batch of senders we received had split/torn filter socks. Since you probably can't get a replacement for the long one, may have to reuse the old one or go with a standard, short one. Not a problem if you do.

[spork2367]

These are definitely going to be one of the next hard to find items. There was a place selling three on ebay for 311.00 a piece that I had bookmarked and they were all sold in the last week.

Does anyone know if you can get just the black piece that holds the long pickup up to the pump housing?

Check the socks, both of them. The last batch of senders we received had split/torn filter socks. Since you probably can't get a replacement for the long one, may have to reuse the old one or go with a standard, short one. Not a problem if you do.

Long ones are available. Just bought one last week.

[9T1 Red ZR1]

Thank you for the information, Jerry. I will check the socks during installation.


Bill

[jss06c6]

Carid does not show any.. Eklers has two in stock for $444 each!

Carid does carry racetronix pumps (walbro) for $89 each. Can these be retrofitted into the LT-5 assembly?

Jerry, do you carry the fuel pump gasket?

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[jss06c6]

Found one and ordered from Parts Train ($378 shipped).

Refurbished the Sending Unit.

1. Carefully open the two tabs on the winding side of the potentiometer
7309
2. Slowly lift off the winding housing by lifting away from the two tabs that have been bent open and ease off of the wiper shaft
3. With WD-40 and cue-tip or clean shop towel (blue paper), very carefully wipe the windings clean..
7310
4. Then, using a new cue-tip or shop towel (blue paper), clean the wiper contact (brass). Mine was black with 27 years of junk.
7311
5. Gently flex the contact tip spring open so that you get a little more spring pressure on the wiper/winding contact (see photo under step 1)
6. Reassemble by slipping the housing back under the tab that was not opened and over the wiper shaft. Then bend the two tabs you opened back down to secure the unit.
7312
7. Recheck full sweep on the potentiometer, making sure it reads steady at any point (no matter how much you move the float shaft side to side) and that it smoothly sweeps from 1.4 ohms (tank empty on mine) to 92 ohms (tank full on mine).
7313

Note: I could get the sending unit to be erratic before opening and cleaning the potentiometer by moving the float shaft side to side, especially at the tank full position. Further, I could duplicate the lack of response in the top range of the sending unit. There was enough junk on the wiper contact and the windings to cause it to be erratic. After this rebuild, the unit is rock steady, no matter what the position of the float arm!:salute:

[HAWAIIZR-1]

Great job and thanks for sharing with detailed photos and all.


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[A26B]

Jerry, do you carry the fuel pump gasket?

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No, it's commonly available so no justification to tool up for it. Thanks for asking though.

[9T1 Red ZR1]

Hi,
I typed in FLS1102 in the search and it shows two in stock. Before I bought mine, it showed three in stock. It seems that they are correcting their inventory.


Bill

[spork2367]

Found one and ordered from Parts Train ($378 shipped).

Refurbished the Sending Unit.

1. Carefully open the two tabs on the winding side of the potentiometer
7309
2. Slowly lift off the winding housing by lifting away from the two tabs that have been bent open and ease off of the wiper shaft
3. With WD-40 and cue-tip or clean shop towel (blue paper), very carefully wipe the windings clean..
7310
4. Then, using a new cue-tip or shop towel (blue paper), clean the wiper contact (brass). Mine was black with 27 years of junk.
7311
5. Gently flex the contact tip spring open so that you get a little more spring pressure on the wiper/winding contact (see photo under step 1)
6. Reassemble by slipping the housing back under the tab that was not opened and over the wiper shaft. Then bend the two tabs you opened back down to secure the unit.
7312
7. Recheck full sweep on the potentiometer, making sure it reads steady at any point (no matter how much you move the float shaft side to side) and that it smoothly sweeps from 1.4 ohms (tank empty on mine) to 92 ohms (tank full on mine).
7313

Note: I could get the sending unit to be erratic before opening and cleaning the potentiometer by moving the float shaft side to side, especially at the tank full position. Further, I could duplicate the lack of response in the top range of the sending unit. There was enough junk on the wiper contact and the windings to cause it to be erratic. After this rebuild, the unit is rock steady, no matter what the position of the float arm!:salute:

And just to note, this is the early style assembly with the enclosed sending unit. The later style has a flat exposed sending unit.

[jss06c6]

Good to know that! Wasn't aware that there was a revision to the design..

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[spork2367]

Check the socks, both of them. The last batch of senders we received had split/torn filter socks. Since you probably can't get a replacement for the long one, may have to reuse the old one or go with a standard, short one. Not a problem if you do.

Do you know what the AC Delco TS number is for the original long sock with the hole in the end?

[PhillipsLT5]

ACDELCO TS1
ACDELCO TS3
ACDELCO G1
AIRTEX E3240
AIRTEX E3240

[spork2367]

ACDELCO TS1
ACDELCO TS3
ACDELCO G1
AIRTEX E3240
AIRTEX E3240

While the ts3 fits and works, it’s not technically correct. The end seams on the original are rotated 90 degrees from each other and the far end has a hole to go over a pin on the housing.

[jss06c6]

Gents,

Has anyone upgraded the pumps to the Racetronix (Walbro) 255? Higher flowrate I believe and good quality.

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[jss06c6]

New ACDelco fuel pump/sending unit got here today. Long sock is torn at the bottom heat fusion joint! Guess I'll try to get a replacement, or maybe I can get them t send me a new long sock/strainer? No guarantee that the replacement won't be torn too..same type as in the pic from spork2367 above.

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[jss06c6]

Check the socks, both of them. The last batch of senders we received had split/torn filter socks. Since you probably can't get a replacement for the long one, may have to reuse the old one or go with a standard, short one. Not a problem if you do.
Jerry,

This is the exact problem I just encountered with a new unit. If I can't get a proper replacement, I'm tempted to reuse the sock from the one I just repaired..

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[spork2367]

New ACDelco fuel pump/sending unit got here today. Long sock is torn at the bottom heat fusion joint! Guess I'll try to get a replacement, or maybe I can get them t send me a new long sock/strainer? No guarantee that the replacement won't be torn too..same type as in the pic from spork2367 above.

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Jerry,

This is the exact problem I just encountered with a new unit. If I can't get a proper replacement, I'm tempted to reuse the sock from the one I just repaired..

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I can’t find the correct long one anywhere. The place you bought it from is just a middle man warehouse, they won’t be any help. The TS3 is close dimensionally. If the old one isn’t brittle I’d just use that.

[jss06c6]

I can’t find the correct long one anywhere. The place you bought it from is just a middle man warehouse, they won’t be any help. The TS3 is close dimensionally. If the old one isn’t brittle I’d just use that.
Ok.. thanks.

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[jss06c6]

Torn sock as received.. will put Racetronix socks on the unit..[ATTACH]

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[spork2367]

Torn sock as received.. will put Racetronix socks on the unit..[ATTACH]

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You could try heating up two pieces of metal and melting the end back together further back.

[jss06c6]

Put the old sock on the new assembly and installed it. Took the car out for spirited drive. All good. Sending unit working well..[ATTACH]

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[Johnny5]

I just received my 1991 ZR1 and fuel gauge was at 1/2 tank when shipped, I received it with same mileage but tank read 1 or 2 bars. Also i filled up put seafoam and drove a little but my Range still says 19 miles with a full tank. Is this a sign of bad fuel sender? Also
My car is bogging, jerking very bad.
The injectors were replaced but that is it.
Would stuck fuel sender cause this as well?

If I pull the plenum I will do coil packs, plugs, and wires as well but I want try to diagnose why the car os bogging bad and not getting any power. It does it in full power mode and normal. Vacuum pump seems to stop and not run constant.
Anyone experience this and know where to start without pulling the plenum?

[mlipmd]

Measure your fuel pressure, you may have a bad pump or leak in the system.