ihad a similar problem when i installed mine....
it was the bulb cover for me. soon as i plug the light in the back it'll move the needle.
i made sure that the light's color cover is fully stretched and when i installed it in the back i tried not to put to much pressure on it, soon as i saw the needle move i just pulled it out again and stretched the light cover so it'll clear the back.
hope this helps.

 

okay i just messed w/ it a lil more the gauge works reads vac and boost....kinda....it just wont settle on 0 it settles on 15 when at wot it maxs at thirty and at idle its between 2-5psi. its reading right it just wont settle on 0 is there anyway to fix this... cincy heres the guage and specs.
its from marshall instruments. the box i had said engine works...? idk i may have got shitted out of that 40 bucks








2-5/8" Vacuum/Boost[/b]







2-5/8" Vacuum/Boost
VAC/BOOST Gauge. 2-5/8" Black Dial, Mechanical Performance Gauge
High performance at an affordable price. Our 2-5/8" Comp II full sweep mechanical gauges are ideal for street, sport compact, strip and oval track use. They feature rugged bronze bourdon tube movements, white or black dials, bold and easy-to-read numbers and bright orange pointer. Though-the-dial lighting provides crisp, illuminated numbers and markers at night.
Gauges include a chrome bezel for a retro look and anodized silver snap-on trim ring for a modern sport appearance. Gauges include necessary tubing kits and mounting hardware.
Vacuum/Boost gauge includes tubing kit, mounting hardware and 12 volt lighting.

 

faulty gauge if you ask me. return to sender and buy another.

 

^ nuff said

 

i wouldnt take that gauge for free....bad gauge

 

yea it wasnt the guage i really wanted but it was the first day i had off in the past 3 months working 60+ hr. weeks, it hasnt rainedhere in nc where i live in 50+ days. which means no rain, no break from work. i finallygot a day off andhad time to play with it a bit, only gauge i could find in 2-5/8 so i got it. oh well at least next time it will be as simple as hook up a hose and two wires.

 

why 2 5/8's? most common gauges are 2 1/16 and fit with either a vent ring or the Ubracket that comes with it

 

I think 2 5/8" gauges are pressure fit into the vent without the modshack adapter.

 

make sure to cap that vac line or keep the gauge hooked up until you swap it out with a newone.

 

went 2-5/8 just didnt like the ring around the gauge... just personal preference i guess. i took the trim ring off my guage and just glued iton to the trim ring for thevent, put it all back togetherit looks like it came from the factory that way. yea i lost a vent for now but im might tie that vent into myvent at mefeet idk what im gonna do yet. right now its just blocked off.





sorry shitty cam