I need some input on whether I am dealing with one whole issue here or multiple issues.

The ac started blowing out of just defrost vents at idle. Checked vacuum lines and connections because that was a problem once before. No issue there upon initial inspection.

Started noticing puffs of smoke coming from the blow by sometimes at idle a month or so ago. Once again I checked the lines and connections with no visible cause noted.

Took the truck camping a couple weeks ago and encountered some pretty good grades going. Was pulling a three horse slant with just camping gear in it. Truck ran pretty good with the exception of visible smoke coming from the blow by continually at idle once we reached our destination.

Here is where the other issue comes into play. Fuel pressure gauge was reading 16.5 when we left for the trip. By the time we got home it was just below 16. Truck sat for a couple weeks, don't ask, after we got back before I could repair a trans cooler line that sprouted a pinhole on the trip home. Fuel pressure is now at 10. This time there is only expansion air in the fuel gauge line, so that isn't the culprit. I am thinking I should maybe change the actual fuel filter on the truck since it has about 5000 miles into it right now. I just cant see that causing a 5psi drop in a matter of two weeks while sitting.

I am taking the truck to my neighbors in order to check the vacuum system on the truck in the next couple of days. I visually inspected all lines and connections yesterday, including the check valve at the firewall and can't see an issue there.

Am I dealing with a vacuum issue and a fuel pump issue, or could they be correlated? Please forgive my ignorance here. It seems no matter how much I learn, there is that much more to still learn.

 

Not related I would try the fuel filter first. I forgot which pump you have. You should put a fuel pressure snubber at the sender unit if you haven't already the surge of fuel pressure can damage your gage.
As far as the vacuum issue could be something jammed in the defrost door like a pen. The door should move freely.

 

Thank you for your reply! I have the Fass 95. I have never even heard of the fuel pressure snubber, so that will tell you that I don't have one. I will research those as well as the defrost door.

 

The snubber acts as a fuel surge protector so your fuel pressure transmitter/sender doesn't get damaged. Here is a link to the ISSPRO manual for installation of the snubber. I killed an Autometer sender once by not having this installed and at 75 dollars for a new sender verses 5 bucks for a snubber it is good insurance.
Your Fass isn't that old so I doubt you have a pump fuel pressure problem. Never know though every manufacturer can miss "QC" and send junk out in a box.
Here's the link:IS169.pdf

 

How do you tell if the sender is bad?