aaddpp

I finished up my fuel line refresh last night, and pressurized the system by jumping the relay points. The system went up to approx 52-55 psi as measure by the gauge I recently installed on the fuel rail. All lines seem to be fine expect for the connection coming off the fuel cooler - specifically the line that comes off the cooler and then snakes around ultimately leading to the fuel pressure regulator (passenger side, toward back of engine). For the record I have an early 87 S4.

There is no visible fuel dripping from the connection at the cooler, but when I rub my fingers all around the coupling, I can bring them to my nose and smell gas. I think I may be able to tighten it a touch more, though it is pretty tight and I would be somewhat cautious about doing this.

Based on what I see, I think it seems to be a slow leak since there is no noticeable dripping. Would it be possible to use some Teflon plumbing tape to assist the coupling to seal up tighter? If not, what should I think about doing to remedy this and make the line as secure as the others.

Thanks,
Dave

SeanR

Do you know if it is coming off the attachment at the fuel cooler? Those are a pain with the line/screw end that goes inside the fuel cooler. They can be cross threaded.

billtool

I had the same problem...same fitting. It's that damn 37 degree fitting. What fixed it was one last crank on the collar nut. Turned about an eighth of a turn hard and no more leak. Holding the FPR nut tight, of course.

aaddpp

It seems to be coming from this attachment point you mention...i.e. the threading between the cooler and the nut that secures the line. Nothing visible dripping, but when I rub the area with my fingers to test for gas, I can smell it on my fingers and believe I can see light gas residue (a little shiny) on my fingers.

As far as tightening, I don't believe I can make it any tighter than it is without damaging something.

I think if there is a way to add a sealer in the threading (i.e. Teflon tape) it might solve the issue. I just dont know if this is something you can do or if the fuel will degrade the sealer over time.

Dave

ROG100

Dave,
Go to Home Depot ( I can't say Lowes as I have too many customers who are also HD senior employees and would disown me). They have teflon tape suitable for gas - yellow IIRC. Apply it very carefully only to the threads and ensure you do not get any surplus tape into the fuel system. Also say a prayer to the 928 gods - that should do it.
Roger

Bill Ball

Unfasten the fitting and make sure the sealing surface faces are clean. The threads are not what seals. The fuel fitting torque values are not that high, and many people overtighten them.

ROG100

Never listen to a salesman - do what Bill says.

Mrmerlin

before installing the collar nut put some anti seize onto the rear of the line where the nut touches and the threads of the cooler this will let the nut turn more without galling the surfaces and also you will be able to remove the connection in 19 years

Lizard928

Listen to Bill and Stan,

Teflon tape is not a sealant it is a lubricant to prevent thread galling, mainly used on NPT.

Ensure there are no niks or dings on the mating surfaces.

ROG100

As Colin says listen to Stan and Bill.
However the whole point of PTFE tape is to lubricate the threads to pefect the seal.
It allows the joint to tighten better without galling on the threads.
Anti seize would work as well

aaddpp

Would a copper based anti seize be the way to go, or something different?

Don Carter

Good save Roger! :-)

Just did a refresh yesterday, no leaks so far, but only have 30 psi on the system currently.

aaddpp

At 50-55 psi, have I pressurized the system beyond normal operational parameters?

ROG100

No your pressure is normal - Don's is low.

Don Carter

30psi is normal for an 85-86, but I'm increasing the pressure to go with Ken's chips which need 55psi by installing an 87 FPR. There was a mix up with the part, so I am still at 30psi for now.

May be calling Roger...