Fuel Pressure Gauge problems..

[7FA]

I installed my FP gauge this weekend, but I'm not sure it is working right. I filled the isolator and line up with antifreeze and have the pressure tap at the CP3 with the tapped banjo bolt. I have 2 concerns.



1) Should the pressure bleed off the gauge after you shut off the engine?? My gauge is staying pressured up and only drops a tiny bit overnight.



2) The gauge pressure readings are a little screwy also. When I 1st started it it was running 7-8#, but I noticed about 10 minutes later it had crept up to 11#. That night I noticed it was now at 15#. I cracked the line at the isolator and it was indeed pressurized, so the gauge is not sticking. Today when I started the truck it went right to 8# like before and within an hour it was back up to 15#. It also does not seem to drop any when I get on the throttle.



Something seems weird... Any suggestions??

 

[05mxdiesel]

I just installed a fp guage this weekend. Mine will go directly to zero after shutdown and the highest readings I get is when I am downshifting coming to a stop which will read 9-10. I am also seeing 3. 5-5 wot with TST on 3/2.

 

[john3976]

I get 9 pounds at idle, gauge goes to zero pressure when I turn off the engine. If I let off the gas to slow down the most it has ever wnet to is 10 pounds and then bleeds down to 9 pounds.



What brand gauge do you have, I have ISSPRO gauges.

 

[SLO CTD]

I also just installed my FP gauge this weekend. Like John3976, around 9 at idle and drops to 5-6 at WOT. Bleeds off when turned off. Don't know about your problem, sounds like something is off. When you bled off the isolator, did you bleed off the fuel side too? Perhaps an air bubble in the fuel supply to the isolator...

 

[7FA]

Well, I may have found the problem. . I had the line filled 100% with anti-freeze. Another TDR member suggested I drain some of the anti-freeze out and allow a small air "cushion" in the line. I just finished doing this and the pressure is running 8-9# at idle, pulls down to 6 under heavy throttle, and drops to 0 after shutdown.



Looks good to me!!! Thanks for all the help!