I installed an Isspro mechanical fuel pressure gauge with an isolator and used the test port on the top of my fuel filter canister in my 99 3500 ram. Anybody know what reading would be normal. I heard from a diesel performance shop it should be 12 or 14. My pressure runs at about 7 and drops to about 4 when the truck is under load. Just wondering if this is normal or if the guage is not working or if I should have used a differentspot to pull the pressure reading.

 

its kinda low,maybe its time for lift pump upgrade before vp44 die

 

You seem to be having the same problems as my 98. I connected my mechanical gauge to the inlet of the VP pump with an adaptor. I get 12 psi at idle and 8 to 10 under load. I have a new filter and lift pump. Make sure you are on the outlet port on the filter housing so you will read post filter.

 

Has your lift pump been replaced with one that is in the fuel tank? If so, those look like normal numbers.

 

I'm not sure if m lif pump was replaced but i do know that I dont have a pump in my tank, I do however have a pump on the driverside frame rail, weird huh.

 

Sounds like you are still running a stock lift pump. It's not a matter of IF it's going to die, it's a matter of WHEN. If I were you, I'd install a FASS as soon as you can.