Installing Fuel Pressure Gauge

dennisL

Member
Joined
Aug 19, 2002
I just installed a fuel pressure gauge and used a "T" adapter at the end of the fuel rail for the sending unit. I removed the schrader valve before attaching the adapter, then I put the original fuel rail end cap on the end of the adapter, but now it leaks (a lot). With no schrader valve, the end cap can't hold the pressure.
Can I put a sealant on the adapter threads and if so, what kind?

Sorry for the very basic question, but I'm a computer geek. :D
 
Thanks, I have both but was reluctant to use the tape, for fear some of it might end up in my fuel system.
 
I just installed a fuel pressure gauge and used a "T" adapter at the end of the fuel rail for the sending unit. I removed the schrader valve before attaching the adapter, then I put the original fuel rail end cap on the end of the adapter, but now it leaks (a lot). With no schrader valve, the end cap can't hold the pressure.
Can I put a sealant on the adapter threads and if so, what kind?

Sorry for the very basic question, but I'm a computer geek. :D

Don't forget that the fuel rail outer threads are STRAIGHT threads, not tapered like pipe threads. I would not trust anything to seal over the long haul and especially to be safe on gasloine under the hood. That end cap is really just to keep foreign matter out of the end of the rail. What kind of sealing does the pressure gage have? Where did you get an adapter with those threads?
 
I would not trust anything to seal over the long haul and especially to be safe on gasloine under the hood. That end cap is really just to keep foreign matter out of the end of the rail. What kind of sealing does the pressure gage have? Where did you get an adapter with those threads?

Leaking gas under the hood is my concern as well.
The pressure gauge was made by ATR specifically for the turbo Regal. It came with a short hose (one end fits the straight threads) and a long hose to reach the windshield for a quick wot test.

The new "T" adapter came from Jegs. Its a -4AN female to -4AN male with a 1/8 NPT female in the middle for the sending unit. I ordered it thinking I could tap the center of the male end for the schrader valve but later discovered these valves require a special tap. My goal is to maintain the end cap for easy removal.
 
Leaking gas under the hood is my concern as well.
The pressure gauge was made by ATR specifically for the turbo Regal. It came with a short hose (one end fits the straight threads) and a long hose to reach the windshield for a quick wot test.

The new "T" adapter came from Jegs. Its a -4AN female to -4AN male with a 1/8 NPT female in the middle for the sending unit. I ordered it thinking I could tap the center of the male end for the schrader valve but later discovered these valves require a special tap. My goal is to maintain the end cap for easy removal.

The factory rail end cap has a small o-ring at the bottom which seals against the tapered end of the rail. The end of your adapter may be shaped differently and not allow a seal. I notice that Jeg's has 4AN end caps (Earl's #361-592904 ) for fuel systems. They don't mention how they seal or what keeps them tight in use, but you might take a look. This is the same thread used on the old R-12 refrigerant hoses and they all seal well with the little rubber seals that they have, but they also are knurled to indicate hand tightening and for short time use.
 
has any one had the same issue with the kit that g bodys has im planning on ordering one but im worrys about leaking
 
I got the metco gauge (from G-body)that is slids under the windshield bottom trim and had no issues with making a leak free connection to the end of the fuel rail. Great tuning tool.

Carl
 
Paul, this is the tee adapter I used. I think the problem (leak) was because I used the original 25 year old end cap from the fuel rail on the end of the new adapter. It sealed ok on the fuel rail but it had help from the schrader valve. No valve in the tee adapter.
555-110532.jpg
 
that needs a -4 an cap and it needs to me more than finger tight (needs to be wrenched on)

that fittng is designed more for a flow through setup
 
Yea, I figured as much so I ordered a new 4AN cap but just in case it still leaks, I ordered new adapters to connect the fp sender to the rail without using a tee. A 4AN female to 1/8 npt male straight adapter, and 1/8 npt female to 1/8 female 90 degree adapter for the sender.

I thought the tee would be nice for easy, quick attachments but not at the risk of a fuel leak.
 
Here are pics of my install. The only issue with this style gauge occurs when the hood is opened. The gauge bracket slides out of the windshield trim and you have to place it back while dropping the hood to re-position. Carl

IMG_20120213_160801.jpg
IMG_20120213_160657.jpg
IMG_20120213_160706.jpg
 
ever think of trying to mount it on the hood all you would need is a couple of elbows at the gauge how hard is it to se from drive seat im wondering before i buy it and regret it
 
Have thought about mounting to hood, but like you said, would need some sort of elbow. I've got the gauge setup so that 60# is at 12:00 so under boost a quick look at where the needle is, tells me I'm OK. It's easy to see where it's located. For$100 it's a no brainer for me. I will tell you that the more I'm learning about the car and watching gauges, the 02 millivolt scanmaster is 1st place to look, and if they seem low, then I'll look at FP gauge.

Will tell you that Richard Clark calibrated my gauge and it's off my 1-2# throughout the entire scale. He gave me a tag indicating what gauge reads, and what actual pressure is. When gauge reads 45, it's actually 43.

Carl
 
New AN cap should solve your problem. There is help if you ever scratch/gouge the sealing surface (37* flare) of any AN fitting. They make soft copper seal washers that install over the flare and are even FAA approved. (we don't use them on new jets, though, we MUST R&R any leaking fitting.)
 
I just wanted to close this with a happy ending. I replaced the original end cap with Earl's (AT592904ERL) black "tuff" cap and it seals great. Thanks to all that offered assistance.

Dennis
 
Top