@Clb Yeah, I remember from 4-5 years ago when the mechanical was going out and I was blowing white smoke, (thought it was water at first), I was reading up on the net and read that the IP can do some of the work of the lift pump but can become overworked and die an early death. I READ THAT ON THE INTERNET!
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Well, I made it across the wash to town and back.
The plot has thickened considerably.
With the pickup line in a 5 gallon can of diesel, the pump was working so furiously that the needle on the gauge was flipping between 4 and 6 PSI. For a long time.
So the gauge was relocated at the filter return.
After the air was bled, the pump held about 4.3 for a long long time without any variation. Just sat there like it was stuck, which it was not. Good volume coming out the filter return.
Soooooooooooo................
I think I have a clue what caused my mechanical to go out. Then I put on a cheapie $40-$50 Facet. Got 4 PSI all was fine. Then more problems developed where I now sit. Got loose for about a $60 Facet that had a higher PSI and lift spec. Could not get 4 PSI consistently.
Did some more reading recently, here I think, and went with the recommendation for a commercial Facet Duralift that could lift 10 feet for refer trucks.
Got my 4 PSI at first. Good and steady. I'd turn the pump on, see 4 PSI then forget it while I tried starting the truck. Then I discovered the PSI was dropping, sometimes to zero. Nope. No air.
I believe I have an intermittent blockage in the tank pickup. There's only about 10 gallons or so in it but it's a steel saddle tank so it's heavy, but it's gonna need to come off to be certain.
The pickup is in the center of the tank with the return at the front. So when the pump is running, there is a circulation........like yall didn't already know this.
But if there is a plastic baggie or two or three, they would drift toward the pickup, especially when the fuel is low.
So that's what I'm betting I'll find.
Sorry for the long winded post, I'm decompressing.