Factory Five Racing Forum banner

1 - 19 of 19 Posts

·
Junior Charter Member
Joined
·
448 Posts
Discussion Starter #1
I filled up the car today and probably more than I ever have before. Drove about a mile and parked it. When I returned I found fuel dripping from the plastic shield. Fuel appears to be leaking from around sending unit, specifically from what appears to be a factory seam. Anybody else have this issue. ImageUploadedByAG Free1476747894.353428.jpg



Sent from AutoGuide.com Free App
 

·
Pro FFR Builder and Moderator
Joined
·
14,598 Posts
why is there RTV all over the sender? There should be none. There is an O-ring gasket that seals it. If RTV was needed to seal it it was ether left out or mis-installed.
 

·
Junior Charter Member
Joined
·
448 Posts
Discussion Starter #3
No rtv Gordon. The silver sending unit was put in with gasket from what I remember. The fuel leak seems to be at the outer seam in black. What you see is the wetness from fuel.


Sent from AutoGuide.com Free App
 

·
Pro FFR Builder and Moderator
Joined
·
14,598 Posts
I really don't see a seam leaking unless it was a used tank from a wrecked car. I can see the possibility of a leak down from above like the sender or the roll over valve. If you are concerned about the tank you can get a new one from O Reilly for around $130.
 

·
Junior Charter Member
Joined
·
448 Posts
Discussion Starter #5
New FFR supplied tank. I'm not sure why that seam appears to be leaking. It doesn't look like it's coming from the silver sender gasket, but I'll see if I can tighten the retaining ring. It's not fully against the stops


Sent from AutoGuide.com Free App
 

·
Snake Farmer
Joined
·
10,239 Posts
Might have been some chance of it leaking all along, but if you never filled it up that far before, what little may weep from day to day driving, might evaporate before it became obvious.

I would tighten it to the stops, and see if that cures the problem. Chances are the gasket has compressed since first installed, and will allow further tightening. I presume that's why it wasn't tightened to the stops in the first place? If that doesn't resolve the issue, you probably need to replace the seal.

Use a piece of wood dowel, or at least something wooden, to avoid sparks when tapping it to the stops..
 

·
Tool Collector
Joined
·
6,598 Posts
Here is the problem, a common mistake when installing the fuel level sender. The o-ring that seals the sender to the tank needs to have a bit of lubricate so the o-ring does not fold over or tear while the locking ring is installed. You may need to purchase another o-ring if it has been torn. Next time you install it use a bit of petroleum jelly so the o-ring will stay put and not move while the locking ring in tightened. Same goes for the fuel pump/pickup locking ring.
 

·
Premium Member
Joined
·
1,602 Posts
Agree with Frank - I had this happen on my car, exactly the same symptoms you have. No leak when under about 5/8 full but dripping from the plastic cover holes after a drive. When I filled it all the way ... it made a significant mess.

Pull the sending unit and replace the squared o-ring seal. Use a bit of o-ring lube or petroleum jelly when you install the new o-ring to keep it from being displaced when you install the sending unit and lock ring.

4500+ miles later and mine still hasn't leaked a drop.
 

·
Not a waxer
Joined
·
11,552 Posts
Yep, what Frank and Bruce said. Betcha' it's the O ring. Take the sender loose and replace it. When you put it back be sure the new one is well seated in the groove at the opening then lube the surface that meets the locking ring (I always use white grease). Be sure to take the lock ring to the stops---all of them. Believe me on this 'cause as Miller :bat: will tell you I'm the O ring Captain
:wink2:

Jeff
 

·
Too Cheap to paint!
Joined
·
6,130 Posts
I'm another on the O-ring.

I found out at my first track day 11 years ago. First time with that much fuel slosh. Replace O-ring per instructions, all good.
 

·
Cobra Colorist
Joined
·
5,632 Posts
"Believe me on this 'cause as Miller :bat: will tell you I'm the O ring Captain"






WELL! If you're gonna do it then what am I supposed to do......I never have any fun......I'm tellin my mom !!
 

·
Premium Member
Joined
·
1,110 Posts
Hmmmm...The F5 build video (#9, gas tank installation) says to use fuel safe gasket sealant on the O-ring. I hope that's OK, 'cuz that's what I did.


John
 

·
Premium Member
Joined
·
1,110 Posts
So it turns out using the fuel safe gasket sealant wasn't OK, at least for me. When I filled my tank, I got a dripping leak. Based on this thread, I replaced the O-rings under the fuel level sender and the in-tank fuel pump. When I pulled the old ones out, I found that the sealant was hard, almost crystalline.

This time, I didn't use any sealant; rather, I lubed each ring with some vaseline. I also smeared some vaseline between the retaining ring and the flange on the sender & the pump hanger. Filled the tank this morning & no leak. Plus, no strong smell of fuel in the garage. I'll report back after a more extensive shake down.


John
 

·
Snake Farmer
Joined
·
10,239 Posts
So it turns out using the fuel safe gasket sealant wasn't OK, at least for me. John
Tsk, Tsk,..Should have listened to the O Ring Captain..:001_tongue:

Funny why FFR would tell you to use that sealant, when there is a solid rubber seal? Maybe they figured on that being needed, for builder re-using a donor seal?
 

·
Premium Member
Joined
·
1,110 Posts
Yep; as usual Frank’s (& Kleiner's) advice is spot on. But in my defense, I'd already installed the sender & pump with the sealant (didn't know any better & followed what is mostly a reputable source of information). At that point, it was worth a try. Hopefully, other builders will read this & not make the same mistake.

Live & learn.


John
 

·
Registered
Joined
·
20 Posts
Good thread to find as I am almost to this point on my build. I wondered why the FFR YouTube video called for sealant on this oring.
 

·
FFCobra Craftsman
Joined
·
22,115 Posts
FFR, anyone of you following this thread?

We can always hope right? For general info, the standard recommendation for lubing o-rings is lube w/ whatever fluid the o-ring will be sealing. Well that works fine for any liquid that has just the slightest lubricity property. One that comes to mind is brake fluid. Lubricity? Well not much according to my fingers but just enough for a normal assembly time. But gas as a lube? I guess the next option would be a lube that the contained fluid will be Ok with. IE, w/ gas, almost anything would work, because any excess would be disolved by the gas but be such a tiny percentage of the total volume as to be no problem. But then I thought about silicone grease which is my go to in many cases since it won't dissolve anything. But then a car running efi w/ O2 sensors should probably not use silicone. Any other thoughts to add here guys?
 
1 - 19 of 19 Posts
Top