rockatansky

Hi. on my 1980 928, I'm trying to fix the fuel needle marking 3/4 when full. I almost sure the problem is a malfunctioning sender (dirt, etc) because I get the needle 4/4 when bridging the wires (with unplugged sender). So probably the ball is not floating all the way up, and would like to remove and take apart every part of the sender, clean, etc...

I'm following Dwaynes write up (the one for changing the gasket), but the first problem I have found when removing the sender is the hose coming to it. I have no leaks anywhere but before trying to remove it I see it will be tough and I would like to ask before trying, where this hose comes from, and if it is accessible.

In case I break it or if I decide to change it in the process, how can I have access to the other end?. The big question is, will I need to remove the whole tank?.

If I'm not wrong I remember some post about somebody that did a dremel work to access the other end of this hose. I'm not a fan of cutting pieces of the car, but if anybody has a picture of this work, or any clarifying picture of where is the other end of it, it will be great.

Also, in the pet schema I don't understand very well which number corresponds to this hose. Thanks.

Bill Ball

That is the return line. Zero pressure. Should be no problem to remove it. If the rubber is brittle or splits easily, replace it. It runs down the wheel well then under the car to a joint not far forward.

IrishLegend

Check those wires too.

AirtekHVAC

on my 78, the return line is about 6" long, rubber, crimped to hardline, and runs underneath to the engine compartment. It can be disconnected from the trunk. The sending unit is a tricky bastard.

To remove it, you need a long stiff thin object...there is a anti-slosh chamber (ok...I dont know what it is called) in the bottom of the tank, and a "bell" on the bottom of the sender, that you need to work loose to pull it out. you can then disassemble it. The inside gums up....there are two very thin wires and a ground clip that contacts the inner housing of the sender....here are a couple pics of the inside of mine...my ground clip was deterioated, so I had to solder in a new one made out of a 25A fuse.

linderpat

interesting...following

destructo_low

Be careful removing the unit. If you look at the parts diagram, at the bottom of the sending unit, number 8, there is a plastic duck bill looking part. It expands after pushing it through the hole on the top of the tank, and it may lock into the well/ sump at the bottom of the tank, I can't remember. When I pulled my sending unit out, I wasn't aware, and mine broke off into the tank. I replaced my sending unit and gasket anyway because of copious amounts of rust, but I thought you should know.

edit - airtekHVAC is talking about the same contraption on the bottom of the sending unit. I only paid $150 for a new sending unit off eBay. You'll have to buy the gasket separately, because it doesn't come with the sending unit, unless the seller includes it. I think I bought mine off eBay as well for a few dollars once the sending unit arrived without one. Look inside your electrical connector for corrosion. I rolled some emery cloth up and cleaned the copper female terminals where they oxidized.

skippermccoy

I had an issue with my 82 not reading full when it was topped off. The small holes at the bottom of the outer tube were plugged. I had a spare fuel sender assembly to play with so I drilled 4 holes up each side of the outer tube and then put it all back together. Its been like that for about 2 months now and I have not had issue with the gauge reading wrong or the needle bouncing when driving.

jpitman2

That hose connects to the steel line, about 6" from the visible end. I think you would need to pull the tank to get at the other end (not a major job). I replaced my tank and most hoses a while ago (spun threaded insert), and the end of that hose at the gauge head was badly frayed (been removed a few times).It only took a very small tug to pull it off the steel line - the small crimp thing did almost nothing. I replaced with new fuel hose, and a screw clamp, no issues in several years now. It will be easier to disconnect from the gauge head if you loosen the big nut on the head so you can rotate the unit in the tank. Your misreadings on the gauge may be caused by gunk condensed out of the fuel on parts of the wires - you can clean them, but be careful, as they are pretty fine. Also note that the small < shaped contacts on the float should BOTH have the wires sliding on the point of the < - mine had one on the back, which allows the float to turn and lose contact.
If you havent already, check out Snakeskin's page on this item.
jp 83 Euro S AT 54k

rockatansky

Sure, they seem horrible. Specially the ground one has many cooper lines cut resting on the sender cap. After removing the wires I have checked that electrically from the wires coming to the sender, that they are working. I bridged the feed and ground I saw the needle go to full. So the problem is not like the one Dwayne had who needed to turn the needle itself at the gauge to reach the Full mark. My problem should be the physics at the sender. At least, that's what I conclude seeing my needle behaivour by bridging. Here:


Thanks Bill, I see. I think I'm going to replace it. But for your words I'm still not sure if I will have to drop the tank to do it, should I?...

Thanks Ron. My '80 should be like yours. You say you can disconnect the return line from the trunk, you mean both sides?. How?. I have only access to the sender side...

Thanks for the pictures. Seem horrible, mine should be like that too. My car was parked 3 years by previous owner. Deposits, oxid, dirt, for sure, not letting the ball move up and down freely.

Great Ed. I allways feedback my progress. Sometimes it takes long periods of not writing, but I never forget. So keep subscribed to see how this all ends.

Thanks destructo_low. I know the problem. When I raise mine I will cross fingers. I read many posts of people having this same problem, that the sender gets stuck at the bottom. to pull or not to pull that is the question. If mine is stuck I will follow a post where jhc68164 use a long ruler to release his sender from the bottom. Here:

https://rennlist.com/forums/9507517-post10.html

Thanks skippermccoy, Good to know this too, as soon as I solve the return hose problem, I will start with unmounting the sender. I think the problem will be obvious as soon as I remove the exterior cylinder.

Thanks as always jpitman2, I see, so finally I will have to drop the tank... Well, maybe it is no t a major job, but it turns to be a different one, so If I have to drop the tank I will study which parts/hoses I will take that opportunity to remove and replace. I know Dwayne has also a good write up about the tank.

edit:
I found a picture of the return hose from Hilton, seem easy to change when the tank is not in the middle. I attach the picture.

jpitman2

the only HARD part for me was getting the rear end up high enough to get the tank out from under. The rest of it just takes a normal amount of care, and do things in the right sequence. Get the right material to replace the dead anti-chafing insulation. After its buttoned up, to avoid LOTS of cranking, bridge the pump relay to do a leak check, and let it run a few minutes to ensure there is fuel under pressure everywhere, and it should start firsdt try, mine did.
jp 83 Euro S AT 54k

Hilton

Yep, I've replaced it on 3 928's - just using a clamp and fuel line (3/8" from memory). You will need to drop the tank to get at it - but thats not a hard job. It takes longer to drain a nearly full tank out of the fuel pump hose than to drop the tank

Here's a pic of what I found inside my '87's sender.. it was scary. Rust, corrosion, and weird sticky brown tar-like gunk.

When reassembling, make sure you get the wires positioned correctly on either end of the float - if one of them isn't quite making contact with the V you'll get erratic readings.

Hilton

Oh.. here's what the sender looked like after some cleanup - bead blasting, acid dip, and zinc plating. Works just fine now

(I re-plated it in sections - so the float wasn't ever actually in the acid-zinc solution - I wouldn't trust a workshop to take that much effort)

Bill Ball

Replacing the return line...

If you want to just replace the short rubber section, you need to drop the tank at least part of the way to gain access to the end of the metal section. Since this is a zero pressure line, I have no problem with cutting off the old hose and simply clamping a new FI hose section on.

Or you can replace the entire piece, metal section and hose. Price I see is $130+. I think that can be done tank in place.

IrishLegend

Do you have any pics?

zefke

This is a very interesting thread. My gauge does the same!!

Do you know what the holes are for? Sounds interesting but I have no clue how this works!

WOW this looks better then a new one, do you do this at home in an acid zink solution with some DC current??

Did you finally fix the problem or are you still wooriking on this?

Take care
Paul