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Fuel pressure gauge sender install

4K views 18 replies 6 participants last post by  Jeff Green 
#1 ·
Ok so I'm going to install an Autometer 4371 electric fuel pressure gauge. I did a bit of research on lt1's and fuel pressure gauges and since this is going to be a permanent install I figured it safest to run some braided hose to the sender so as not to have much weight on the fuel pressure test port. So I purchased the gauge, a braided hose for fuel with -4 AN female ends on both sides, a 90degree -4 AN male-to-female, and a -4 AN male to 1/8" NPT adapter.
My question is I understand that with AN connections you just tighten without using thread sealant or teflon tape and for the sender to NPT I would use one of the sealant methods.
But for the -4 AN fitting that connects to the fuel pressure port, do I treat that as an AN connection or should I use some teflon tape or thread sealant as I'm guessing that is not a true AN connection but just that -4 AN happens to be the right thread size for that pressure port?
 
#2 ·
Fuel pressure gauge

NEVER use teflon tape,paste,or anything else on an AN fitting ever. The port on the fuel rail is an AN-04 fitting like all the others you mentioned. Tape,and/or paste is for pipe thread ONLY.
 
#3 ·
Alrighty that's what I was thinking but wanted to be sure. Also I appreciate the quick response, love this forum!

Side question: since this is dealing with fuel, would either thread sealant or the teflon tape work better then the other in this circumstance for the NPT to sender connection?
On hand I have teflon tape, Permatex high temp thread sealant, and also some Permatex #3 aviation form-a-gasket sealant liquid
 
#4 ·
Fuel pressure gauge

I use either the teflon tape,or paste. I avoid stuff like Permatex on threads unless I'm desperate.
 
#5 · (Edited)
Like was already said NEVER use any sealant of any type on AN or JIC fittings, only use teflon tape on NPT fittings. Im a little confused though because you said this was an electric gauge but then you're talking about braided hose and NPT adapters? Whatever you do, if it's a mechanical gauge DO NOT for the love of god install the gauge inside the drivers compartment.

EDIT: Ok I just reread your post and now I understand what you're going to do and I say don't bother with all the fittings and hose, just mount the sender directly on the test port and be done.
 
#19 ·
Like was already said NEVER use any sealant of any type on AN or JIC fittings, only use teflon tape on NPT fittings. Im a little confused though because you said this was an electric gauge but then you're talking about braided hose and NPT adapters? Whatever you do, if it's a mechanical gauge DO NOT for the love of god install the gauge inside the drivers compartment.

Most of today's mechanical fuel pressure gauges do not allow fuel past the sender that goes on the fuel line. The line for the sender to the gauge is full of a solution that is water based and will not freeze but more important is it has no fuel in that line from the sender to the gauge. So mounting a mechanical fuel pressure gauge inside the car should not be an issue if you're using a quality sending unit. All of what Auto Meter sells today are that setup. NHRA and safety requirements kind of took care of that problem for most people years ago.

So if you want a mechanical fuel pressure gauge inside the car it shouldn't be an issue.
 
#8 ·
There are a lot of things that are never a problem,until they are a problem. It's pretty easy to install AN adapters to the fuel lines also. Especially,if one has an "aftermarket" fuel pressure regulator. Which generally have a removable fitting that accepts the hard-line. I use a teflon/braid line coming from under the car where my AN fuel-line connections meet. It goes both to a mech. gauge under-hood,and a sending unit which operates an electric gauge inside the car. This system works well,and the two gauges confirm each others readings.
 
#9 ·
Any chance you could post a pic of the installed sender? I'm about to do mine and would love to see it.
 
#10 ·
The car is up in the air inside the garage right now. I'll try to get a good angle of the install,and post it later tonight.
 
#11 ·
Awesome. I'd appreciate it.
 
#12 ·
Hopefully these will give you the general idea. The electric sender is tied to the mechanical gauge using a "tee". The source is an AN-04 teflon braided line leading down to inside the chassis rails,to another "tee" where the front part of the fuel line meets up with the line coming from the tank.
The braided fuel/return lines disappear into the cowl near the brake booster,and reappear on the other side of the booster near the fuel rails.
I was able to get enough light behind the underhood gauge to barely show the line supplying pressure to the gauge,and the sending unit for the electric gauge in the cabin directly behind it (out of view).
These are the best angles I could get. The gauge cup is mounted on one of the threaded studs that secured the original firewall insulation. With two gauges it's easy to compare them with each other,and having one right there handy under the hood if one is altering the fuel pressure is great.
 
#13 ·
Wow! That setup looks clean! While I'd love to run a system like that, I'm still running the stock lines.

Can I just tap into the shrader after pulling the core and hook the sender directly to it until I can save enough money and time to run something similar to yours?
 
#14 ·
In theory,yes. I like the idea of running a AN-04 teflon-braid hose (available assembled in various lengths from AutoMeter,and others). The fuel rail port is AN-04 (bet you didn't know that,I didn't) If you're running an adjustable fuel pressure regulator,or plan to. That's when you really need one. Some regulators include a port for this purpose.
 
#16 · (Edited)
haha thanks, Slow. I almost knew that. I knew it was 7/16-20 but was not too familiar with AN numbers but a quick glance at a chart and it says it's -4.

Thanks for the help! My sender looks like it has a flared male thread on it but I don't know what size it is. A 10mm threads most of the way up (AN -3?). Then I have no idea what to do with the smaller fitting. I feel like such a noob. cwm6
 
#17 ·
I suspect the sender is pipe thread.
 
#18 ·
Which is probably NPT. Thanks again for all your help, it's members like you that make this forum great for us.
 
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