I've got about 170kmiles on my truck, 15k are mine. PO said the LP and IP are all original. I put a FP gauge at around 160k and was pleased to see 14psi at idle, 9 at WOT. After I put some more miles on it, there would suddenly be times when it would drop to around 3psi. If I shut the truck off, and immediatly restarted, it would be good again. After a little bit, it was getting worse, where this trick wouldnt work. I changed the fuel filter and everything seemed good...until yesterday.
I have 2k on the fuel filter, and the pressure dropped to 3psi. Shut the truck off/on, got my FP back.
Does this sound like some electrical issue with the LP? I know its possible for the filter to be clogged after 2k.
Thanks, Tony

 

Your LP is going out.

Change it to a FASS II and forget about it. Your FP guage will become the most boring guage in your truck. Thats a good thing.

 

I have read lots of similar reports and wonder if the fuel pressure drop problem is in fact a venting problem with the tank. I have worked with pmps of all kinds and what is being described is like a problem with not enough air getting in to release the fuel properly.

 

Easy diagnosis..
change the filter and leave the filler cap cracked a bit and see if that does the trick.
You gotta change the filter eventually so it's basically a free move.
other then that you can move your guage to the pump side of the filter too then you can see the pressure drop across the filter.

 

I'm pretty sure the LP is dying. On the ride home today, the FP dropped twice. Both times, I fixed it by shutting down and immediately restarting. Seems like an electric glithc with the LP. No codes though.
I just filled up, so maybe it is something with the venting. I'll crack the filler cap and see.

 

I had my pressure drop to 0psi @ wot about a month ago, I was tring out another Diesel fuel at the time so I figure I try to got back to the Diesel company I was using and wham the fuel pressure went back to 15-16psi at idle on the first tank. So you may wanna change fuel companies just to see if the diesel you are getting is crap. If that fails change fuel filter, after that its the LP. I've gone through 2 LP and 1 IP these are the simple tests i do 1st.

 

It's your LP. I had the same symptoms a few weeks ago. New Napa LP, and no more FP loss.

 

Caution! Once you start abusing the IP with fluctuating / low FP, the IP has just contracted a Fatal Disease! Implement whatever you need to in order to keep a solid supply of fuel to the IP, and start saving your money, I've read zillions of posts on this site where the LP headed south, and the IP followed...sometimes soon, sometimes a few months down the road! I hope you can break the chain, and I wish you luck, but.....the IP is FAR too $pendy to be just hoping that an intermittent fuel supply will not kill it....

Rauschbo

 

Still havent done anything about this... , just driving my Jeep a lot more
It seems to have gotten worse. The pressure drops to zero, not 3-4psi. I've perfected my rolling restarts, just flash the key off/on, the fuel pressure immediatly climbs to the happy zone.

This really doesnt seem like a failed LP to me, since a simple 'reboot' fixes the pressure. Could there be a bad relay or something in the computer gone bad? I just hate to replace (and relocate) the LP only to find the problem still exists

 

CHANGE YOUR LP! Mine was doing the same thing as yours and it was bad. I only let mine drop 5 or 6 times before I replaced it. Also, Gieco is right, I went with the FASS II and don't worry about it any more.