There are two different types. The first one runs inline with the line going to the gauge. The next is pretty straight forward also. You simply plumb the housing inline just like a filter and the gauge line plumbs to the housing. The Holley wasn't moving the volume that the Airdog is so the gauge worked better.

 

Based on the vid, I would almost bet the gauge is trash. Usually the way it;s climbung and dropping indicate the gauge is beat to death from no isolator.

I would try it with another test gauge just to be sure.

Dave

 

I installed the isolator and the rapid vibrating went away, but my FP still fluctuates. It doesn't do it any where near to the extent that it did before the isolator, but it still moves a little bit. I'm going to hook up my buddies FP gauge to see if my gauge is bad.

 

Let us know how it turns out

 

I installed the isolator and that cured the rapid back and forth movement of the gauge, but I'm still not getting a steady FP. It will usually stay at a little over 15PSI, but will creep up to 18 or 19PSI slowly and slowly fall back down to 15.

Also I disconnected my batteries and now when I turn the key to the start position the fuel system primes and if I bump the starter it the pump will run for 25 seconds like it should. But I noticed that when I bump the starter and the pump runs it will build PSI up to 19psi and drop back down to 15 and when it drops I can hear a clicking noise from the pump. Does that have something to do with a PSI relief valve opening up so that the excess fuel will go into the return line?

 

Are you running the pump through a relay? The relay may be going bad & clicking on/off. Are you sure that the drop in psi isn't because the heater grid is drawing the power down to the lp & showing a psi drop?

 

Sounds pretty normal and working correctly to me. The LP is regulated so if the pressure exceeds 17psi it will bypass to the return. You dont want anything over 12psi at idle. What is it holding while driving?

 

It's not dropping below 14.5 while driving.

Cummins724, I'm running the relay that was included with the wiring harness.


It seems that a 3-4psi increase and drop would were out the VP44 diaphram prematurely though.

 

Should be seeing higher pressure under normal driving. The PRV may be popping off too early.