Bad fuel pump
Regarding isspro, i thought my choice was good as well. When the 1st sender went bad i attributed it to its location. They sent me one free of charge, but it must have been under warranty. This one there was no reason for failure and I'm disappointed in their product. We'll see what they have to say monday.
When i purchased my gauges, there weren't really any solid monitors/programmers with inputs for egt and fuel pressure i could find. Now I'd do it all over differently, there's some pretty nice stuff or there.
It felt so wrong starting my truck with fuel pressure reading only 30psi. I felt confident in my testing though, and as the engine warmed up the sender, pressure came up to 65.
Called diesel manor where i bought my gauges from this morning and they were pretty helpful. I guess isspro had been using a supplier based out of the US for their sending units. The company started manufacturing in china and they had a ton of problems. Isspro switched to another US based company and the newer senders are supposedly doing better.
Another thing that is now recommended is to install a snubber before the sending unit. The snubber dampens pressure spikes and small variations that can damage the sender over time. There are a couple different types of snubbers - one looks like a filter, the other is a cylinder and piston configuration. Through searching the internet a bit, i found mention of using a needle valve barely cracked open to get the same effect.
I called isspro, and they couldn't confirm whether i got one of the chinese senders or not, but it is the old brass one so they are sending the new stainless one with a snubber. I did have to purchase the snubber though, which they sold to me at cost. I am happy with that and should have the new parts in a few days.
Here's some pictures that may be helpful for someone else in a similar situation.
New Sender
Old Sender
Snubber








