Thom Posted June 28, 2022 Report Share Posted June 28, 2022 With a full tank of gas my fuel gauge reads 3/4 full, and of course bounces around when car is in motion. Could that be a result of a faulty gauge or possibly a faulty sending unit? If the sending unit needs replacement does the fuel tank need to dropped to replace the sending unit? Thanks. Link to comment Share on other sites More sharing options...
Desert Driver Posted June 28, 2022 Report Share Posted June 28, 2022 Most of the time the sending unit is the culprit (the float goes bad). If your Avanti gas tank is like mine (1971), the sending unit can easily be removed when you take out the upright portion of the rear seat. Link to comment Share on other sites More sharing options...
pantera928 Posted June 28, 2022 Report Share Posted June 28, 2022 I have never seen a gauge fail but many sending units go bad Link to comment Share on other sites More sharing options...
Thom Posted June 29, 2022 Author Report Share Posted June 29, 2022 Thanks for the assistance guys. I will try removing the upper portion of back seat and see what I find. Guess I will need to remove the sending unit and see if I can match it to existing Avanti replacements. I have not been able to find any suppliers listing a replacement part specifically for a 1987 Avanti. Hopefully some parts from previous year Avantis will fit. Would removing the sending unit require that the tank be drained? BOOM ???????? Link to comment Share on other sites More sharing options...
pantera928 Posted June 29, 2022 Report Share Posted June 29, 2022 Never did o e on an 87 but in earlier 1980s Avantis, just remove the back set and you will see it on top of the tank. Remove the signal wire from the sending unit and ground it with the key on and the gauge should go to full. If it does, you will need to replace the sending unit Link to comment Share on other sites More sharing options...
Thom Posted June 30, 2022 Author Report Share Posted June 30, 2022 Removed upright portion of rear seat, solid fiberglass panel. Another dead end. This car is just one problem after another. No wonder Kelly did jail time. May be time to cut my losses and sell this beast. Link to comment Share on other sites More sharing options...
wdaly Posted June 30, 2022 Report Share Posted June 30, 2022 DON'T give up just yet! That fiberglass panel Can be removed. As I recall, you should see screws all around the edge of this panel. Once removed you will find the gas tank. Link to comment Share on other sites More sharing options...
pantera928 Posted July 2, 2022 Report Share Posted July 2, 2022 On 6/30/2022 at 5:15 PM, wdaly said: DON'T give up just yet! That fiberglass panel Can be removed. As I recall, you should see screws all around the edge of this panel. Once removed you will find the gas tank. Exactly. Remember when removing the screws where the longer ones go so you can put them back in the right place Link to comment Share on other sites More sharing options...
Thom Posted July 2, 2022 Author Report Share Posted July 2, 2022 Got up bright and early this morning feeling confident after reading replies to my post. Took the upper rear seat out. Removed the box full of screws and removed the fiberglass panel. After digging thru about 5 pounds if insulation, low and behold there sits the sending unit. It appears to be held in place by two machine screws and a healthy coating of gray sealant. It would appear that I can remove the sealant and the two machine screws. However, the clearance from the top of the fuel tank to the rear window deck is at most 2 to 2 1/2 inches. Searching for a possible way to remove the rear deck, the only attachment I find is 4 rivets on each side along where the upper seat back rests. My best guess is that the sending unit will not clear the 2 to 2 1/2 clearance. 😡😡😡😡😡 Link to comment Share on other sites More sharing options...
wdaly Posted July 2, 2022 Report Share Posted July 2, 2022 I thought the 'original' cars had a speaker in the middle of the rear deck that when removed would allow removal of the sending unit. That said, the 87's & 88's don't have the center speaker but I thought I recall the sending units available from the regular AOAI excellent vendors was 'hinged' in such a way as to make installation possible without removing the rear deck! As far as the "gray sealant" - that may have been added by the former owner for reasons including gas smell. You will want to purchase the rubber seal that seals that hole area / once again available from the good vendors (I'm pretty sure it's the same seal as used on the earlier Avantis.)😳 Link to comment Share on other sites More sharing options...
pantera928 Posted July 2, 2022 Report Share Posted July 2, 2022 51 minutes ago, Thom said: Got up bright and early this morning feeling confident after reading replies to my post. Took the upper rear seat out. Removed the box full of screws and removed the fiberglass panel. After digging thru about 5 pounds if insulation, low and behold there sits the sending unit. It appears to be held in place by two machine screws and a healthy coating of gray sealant. It would appear that I can remove the sealant and the two machine screws. However, the clearance from the top of the fuel tank to the rear window deck is at most 2 to 2 1/2 inches. Searching for a possible way to remove the rear deck, the only attachment I find is 4 rivets on each side along where the upper seat back rests. My best guess is that the sending unit will not clear the 2 to 2 1/2 clearance. 😡😡😡😡😡 I just did a 1980 and the clearance was plenty adequate. Do you have the new sending unit yet so that you can see how easily it will go in? Link to comment Share on other sites More sharing options...
Thom Posted July 2, 2022 Author Report Share Posted July 2, 2022 wdaly, thank you for the response. There are actually two rear decks on my '87. The very rear deck has two speakers and there is another deck immediately above the rear seat. That one appears to be riveted in. I am not that familiar with all the Avanti years but that front rear deck may have been added when the rear seat area was expanded by 8 to 9 inches on the LSC model. I do know that the rear quarter window is about 8 inches longer than the standard model. I located a replacement sending unit at AvantiParts.biz that includes the rubber seal but I can't tell if it is "hinged". Can you tell me who the AOAI excellent vendor is? Link to comment Share on other sites More sharing options...
Thom Posted July 2, 2022 Author Report Share Posted July 2, 2022 Thank you pantera928. I have not ordered a new sending unit as of yet. Was waiting to remove the existing one first to make sure I got the correct replacement. Link to comment Share on other sites More sharing options...
Jim S Posted July 12, 2022 Report Share Posted July 12, 2022 I don't know how you reach the sending units on the coupe body. But on my 87 convertible, the sending unit and fuel tank is easily accessed through the trunk. You can lift and turn the sending unit and work it out and back in. Link to comment Share on other sites More sharing options...
Thom Posted July 16, 2022 Author Report Share Posted July 16, 2022 OK, received the replacement unit from AvantiParts.biz and it does appear to be identical to the one in the tank. Had a friend over to hopefully assist me in replacing the unit. Fiddling around with the new unit it does appear that there is a slim chance that we may be able to get it to fit. However, upon closer inspection of the area above the existing unit there are two solid fuel lines running directly above the unit that make it virtually impossible to remove the unit without removing these fuel lines. It appears that the sending unit was installed before the tank and fuel lines were installed. A masterpiece in engineering and design. Insulation replaced, fiberglass backing reinstalled, and seat back installed. New sending unit returned to its box and retained to be passed along to the next lucky owner of the car. Now its on to the speedometer issues. Everyone have a wonderful day. 😂😂😂 Link to comment Share on other sites More sharing options...
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