This morning I started my truck and I am sitting a very nice 18psi at idle and 15.5psi at WOT, nothing wrong here just normal everyday stuff. Temp outside is 68*F around 2pm

 

Just now I went to the corner store and I started my truck, mind you there is not hard start, and I noticed the fuel pressure is sitting at 12psi at idle and 10.5psi at WOT(for a very short run). Now the only conditions that have changed is the weather. It is currently 9:15pm outside and the temp is 30*F. Now I am hoping this is just because the temp difference is such a drastic change that the fuel is thicker? I also have a little less than a 1/4 tank in the truck. 

 

Is my fuel pressure this low because of the drop in temp outside or do I need to look into something else?

NAPA - PN# WH6820 roughly $8.00 for a the needle valve in the picture. NAPA also sell all the 1/8" NPT brass fitting too for fair price.

NAPA - PN# WH6820 roughly $8.00 for a the needle valve in the picture. NAPA also sell all the 1/8" NPT brass fitting too for fair price.

 

I need a double female 1/4 NPT. My plan is to remove the isolator completely and remove the 1/4 NPT fittings that are attached to it that connect the fuel hose and the gauge. So one side I can screw on the needle valve and then I can take on the quick dissconnect compression fitting vulcan includes in their kit and screw it in the needle valve and then re connect the 1/8" tubing. Should be a quick fix. I will call Napa since they deliver to my work lol.

Well I installed a needle valve inline and removed the isolator. All I can say is the isolator I got must have been a piece of ****. I fired the truck up and instantly 18psi again! Thanks for the help guys. I am happy with that instead of 3.5-5psi I was showing...

Well I installed a needle valve inline and removed the isolator. All I can say is the isolator I got must have been a piece of ****. I fired the truck up and instantly 18psi again! Thanks for the help guys. I am happy with that instead of 3.5-5psi I was showing...

Well I installed a needle valve inline and removed the isolator. All I can say is the isolator I got must have been a piece of ****. I fired the truck up and instantly 18psi again! Thanks for the help guys. I am happy with that instead of 3.5-5psi I was showing...

 

Most isolators behave this way. Just really rare to see a working last for very long either.