Have a big camper pulling trip to Talladega next week and was impatient on installing my Diprical gauges so I took it to a shop that does that kind of work and came highly recommended since I wasn't going to have time to do it myself. Didn't want to pull without gauges. The shop is over an hour away so I had to leave it early and had to pick up the truck after hours and the gauges work normal except the EGT dosen't light up. I couldnt leave the truck so I called the shop the next morning and they said to check the white and grey wires on the back which are connected, they also said it may be the led bulb, my question is how do I get to the bulb in the unit and how do I get the gauge out, does it just unplug on the back of the gauge.
Second what is a normal fuel pressure it should maintain I noticed if I get on it hard the fuel pressue will drop breifly in the red slightly below five but normal around 9-10 range.

 

My isspro wouldnt light up sometimes.

I took the guage out of the pillar and had access to the bulbs that way.

Twist the bulb about a half turn and it will come out. I put some dielectric grease on mine where the bulbs contact the crossbar and it fixed her right up.

I dont know if yours is similar or not, but that fixed mine.

You may also want to check the ground.

 

Can't help ya with 'how to change a bulb' thing, put mine in myself and just checked the boxes they came in, no info on changing the bulbs.
Each gauge has a dimmer though, try fiddling with the dimmer for your EGT gauge, if that doesn't work I'd follow it down to where they tapped into the factor wiring, see if somethings wonky there. Might try a volt meter on the plug to the gauge too, that will prove if it's a bulb problem.
or wiring problem.

As for fuel pressure, mine is at 8 normally and dips when you hhit the GO pedal, dips to ZERO if I have my triple dog on 'extreme'...
Good luck, might hafta take it back to the install place...

 

My Fp stays at 10 and dips down to 4 at wot..

Shane