For Lift Pump Pressure . You can leave this gauge permanently in place so  you can check your pressure anytime to get on top of diagnosis of problems.

Includes a 1.5" Liquid Filled stainless case gauge and with brass internals.  Also includes a solid brass in-line fuel gauge adapter to mount on TOP of the Schrader valve - after you remove the core  to mount it right on your fuel line on most 6.5's just before the IP inlet.

The Schrader valve is just "below" the "T" valve in the second pic and the third pic shows a way to plumb this for permanent underhood mounting.  (click on the little thumbnail pic below the main pic)  A whiteface gauge is shown - with an electric pressure gauge not sensitive enough to pick any fuel pressure at 15 psi and below - so do not think any gauge will do.

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GM epoxies those Schrader valves in and they sometimes twist off instead of unscrewing.    We recomend you install a ball valve also (not included)   so you can block off to the gauge or want to remove it put anything elese on like a fuel tap to draw of fuel for testing or a T for more plumbing etc.  You will need at minimum a 1/8 NPT coupling if you are going to direct mount it under the hood

The 6.5 GM diesel is particularly finicky about fuel pressure and GM has actually spec'ed the lift pump which is too small in spec of 6 to 9 psi.  A 6.5 :"may"  run with low or no pressure, but you are damaging your Injection Pump if you allow it to do so.  the DS-4 Injection Pump on that motor uses "immersion lubrication" and depends on 5 PSI to force fuel oil into and through moving parts internally to keep it cool anr running properly.  Loss of supply pressure will produce a hesitation or "hiccup" or be just plain FLAT on acceleration. Also hard starting and stalling. Without supply pressure, the injection pump is forced to try to  "suck" fuel from the tank instead of being "fed" fuel by the supply pump, which puts undue stress on the injection pump by overheating and providing inadequate internal lubrication and will lead to pre-mature injection pump failures. Normal supply pump pressure according to Stanadyne is supposed to be 5psi idle thru full rpm.

NOTE: This gauge will not work in any  pillar pods unless you make a spacer to bridge the gap to 2 1/16...

1) it will not fit, it is just 1.5" in diameter and the pods take 2-1/16" gauges

2) it is technically not wise and in some places is illegal to mount a mechanical fuel filled  fuel pressure gauge inside the cab.

 

This gauge has 1/8" NPT male threads which come out the back of the gauge. This gauge is a top quality gauge made with a black steel case.

 

Features:
0-15 PSI air pressure gauge with a 1.5" dial plate.

Liquid filled for steady readout
Made with a black steel case, durable for use.
1/8" male npt threads, which measure about 3/8" outside diameter.

 

Specifications:
Material: Steel
Pressure Range: 0-15 PSI
Threads: 1/8" NPT
Dial Plate Diameter: 1.5"
Item Weight: 51g / 1.8oz
Package Size: 4.5 * 4.5 * 4.2cm/ 1.77 * 1.77 * 1.65in
Package Weight: 58g / 2.05oz

 

Package List:
1 * Pressure Gauge  ONLY and 1/4 female flare to 1/8 NPT schrader valve brass adapter

 

 

Electrical and fuel items are not returnable

 

See also https://bigbay4bestbuys.com/content/hydrogen-purity-gauge-and-controller and https://bigbay4bestbuys.com/content/round_digital_gauge  for a non-mechanical version that can  be lawfully mounted in the cab

 

 

Diesel owners see also http://bigbay4bestbuys.com/cetane_booster_lubricity_enhancer