I have a 68 Cougar with a brand new fuel Tank, and a brand new fuel sending unit. And for the life of me, I cannot get the darn thing to stop dribbling fuel!?
I have tried 3 different O-rings, including one that is from a Mazda 6 that fit perfectly around the piece, but i had to trim parts of it to accommodate the flanged ends, but still no such luck. Still slight dribbling.
Tried using a gasket maker designed for fuel uses to secure them into place, and still little dribble spots on the concrete…
Does anyone have a tried and true way of securing the fuel sending unit to the tank with a flange that works or a replacement gasket that works? I am pulling out what is left of my hair trying to figure it out.
Thanks!
Jason
Stupid question, but are you sure it is coming from the sending unit?
Not trying to insult your abilities, but are you turning the locking ring till the tabs stop it?
Having tried the number of different o-rings that you have, it might be the wrong part or the wrong locking ring.
I know on mine I had to lube my o-ring with ky or dish washing liquid to get the o-ring to seat all the way so the locking ring would go to the stop tabs. (I can’t remember which one I used)
I’m just thinking out loud here so I hope some of this helps.
The correct seal is square cut. It is round, but the cross section is square. It needs to be installed with a little bit of lubricant. You can try circular cross section o-rings but I have never seen one work.
I have NOS Ford o-rings here. You need to lightly coat the entire o-ring with vasoline prior to installing it. If you try to do it dry it will spin out of place as you drive the retaining ring into place.
I love that everyone is helpful…
I used Vasoline on the first ring, but to no avail. about a drop every 10 seconds resulted.
The second ring I used a gasket forming sort of goop that held it in place, and even after securing all the way to the hilt… no dice… dribbled faster.
Then I tried the adjusted Mazda ring which strangely was the most promising as it was a drop every 30 seconds or so…
Eventually I went back to the 2nd O ring as it seemed to fit into the groove a bit better, but there is still a small seeping of fuel still occurring…
I have looked online and saw a fel pro gasket that looks like it is a cork structure and much wider that the thin squared rubber things I am using…
Any one have luck with those?
Have you used the correct original style o ring? I have done about a dozen or so of these and it just doesn’t work unless you have the square cut correct diameter seal placed properly in the groove. It also helps to insure that everything is flat straight and clean. If the tank is even slightly bent, and sometimes people will dent the tank, and or the locking ring or even the sender, not understanding how the locking ring rotates and striking inwards instead of counter clockwise to loosen things up. Also, most of the tightening is done by using a long screwdriver to rotate the locking ring, and then lightly tapping it into place. The locking ring has to be properly centered to get it to seal. Given all of that, I have had problems with senders that leak through the connections. This may look like the leak is at the ring, but it is from the electrical connection.
Sweet…
I have used 2 o rings that are from the packages from both brand new sending units… so yes they are squared out… I will check the tank for any denting or burring that might interfere with the O-ring. Good call… When I tap in the locking ring, it typically moves the sending unit out from the exact center, but I am able to move it slightly with the locking ring in place, and sadly doesn’t seem to stop the flow. I am back at it again tonight… 3 nights devoted to it apparently isnt enough… ha ha
thanks for any and all insight…
OK… cleaned all the gasket dressing off the 2nd O-ring
Used steel wool on the tank opening to make sure there were no burrs or roughness.
dolloped the little rat bastard in Vasoline…
And reassembled it all back together…
I am waiting until tomorrow to put fuel back in just to make sure it has time to settle. (is that useless?)
One thing that I wondered was if the Sending unit is the right size? there are tabs on the Sending unit, and there are indents that line up with the sending unit. Yet, it goes in and can spin 360 degrees without even catching or interlocking… Is that normal?
I had this problem once. I got it to seal using gasket compound designed for use on carburetors so it is impervious to gasoline. I coated all sides of the o-ring and assembled it as normal. I never had another leak.
I had the same issue on copycatvert and I seem to recall that it was that the tabs that hold the retaining ring in had bent outward to the point that they were not putting enough clamping force on the sending unit to seal it. Try tapping them inward a wee bit with a small hammer.
I missed your comment about the sending unit being able to spin 360 degrees. This is definitely not normal. The tabs on the sending unit should interlock with the notches on the fuel tank. This is needed to keep the float in the correct position to get an accurate fuel level reading. I think you are correct that the sending unit is wrong for the car or it’s the wrong fuel tank. Do you have the original sending unit to compare it to?
In looking at the picture, your locking ring looks larger than the one that I have? I can easily move both the sending unit and the locking ring around… hmmmm… I saw seepage just from overnight waiting. I used the fuel resistant compound earlier, and of course the only thing that cleaned it off the O-ring was… wait for it… Fuel! … the gasoline dissipated the fuel resistant goop. ha ha
I will try to tap down the tabs a little, I don’t want to bend the opening at all.
Thanks to everyone for the assistance.
The pic I posted shows a 68 Mustang from somewhere on the internets. (My poor cat is nowhere near as clean underneath ) Someone please jump in and correct me if I am wrong that it’s the same setup as a 68 Cougar (except for maybe the electrical connector).
Yes, Mustang and Cougar are the same. Only difference would be if you have an XR-7 sending unit, and then the only difference is the electrical connection.
Since I am about to replace my gas tank, I looked on Youtube and found this: https://www.youtube.com/watch?v=lI_MWC1bRiU which shows how to do a gas tank swap from a pony perspective.
This is the first I’m hearing of the need for Vaseline. When I did my fuel system replacement, the new sender fit into the new tank (using one of the two new gaskets I got – I got one with the tank and one with the sender and unfortunately I don’t remember which I used) without any need for Vaseline and without the gasket coming out of place. The whole tank/sender thing went off without a hitch as far as supplying fuel is concerned, and with no leaks. BUT, the fuel gauge drops down to empty long before the tank is actually empty, and I had to clip the plug off the end of the wiring harness where it attaches to the sender, as the new unit didn’t have that same pin configuration, and wouldn’t accept the plug, as it has no low fuel indicator light. I still haven’t got the fuel level reporting correctly (except when the tank is totally full, then the gauge indicates full) but I’ve been ok with just tracking my mileage and knowing when it’s time to fill up. Seems like the new senders are maybe problematic, sounds like we both had problems but of a different nature.
The use of vasoline, or a similiar petroleum based product, is not required but it generally does make the job go easier and greatly reduces the risk of a leak due to the gasket moving out of position. You probably installed your sending unit with the gas tank out of the car, this also reduces the risk of the gasket moving. There is a far greater risk of the gasket slipping when someone is replacing the sending unit with the tank in place in the car.
That’s correct. With a new tank and new sender, I can’t really imagine why one wouldn’t get the sender installed before installing the tank. Then again, if something goes wrong and it leaks after install, it’s probably not the most attractive prospect to remove the tank to work on it. But maybe still worth doing?
I think it would be wise to put a little gas in the tank while it is out of the car and verify no leaks before installing the tank. Just put a short rubber hose on the sending unit gas pipe and fold it over so it doesn’t leak gas for the check, then drain once you are satisfied you got her sealed up properly.
) Someone please jump in and correct me if I am wrong that it’s the same setup as a 68 Cougar (except for maybe the electrical connector).