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Discussion Starter · #1 ·
Ok so 2 wks ago I had the FASS Titanium 95 installed on my truck. The fuel pressure gauge has been showing 15psi all the time, even when the low fuel light was on and I was stopped for fuel. I completed a 4 day trip towing 11,386 from MI to NM with no issues.

Yesterday at idle while waiting for a red light with no trailer, the fuel pressure gauge needle starting jumping up and down and dropped to 0. The truck had plenty of fuel and it never made any sound like it was starved for fuel or idled rough. Once I started driving again it went back to 15psi but bounced around from 8-15 for awhile.
What causes the change in fuel pressure? Any ideas? :confused013:
 

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I'm having the same issue, but mine didn't start till after a butt load of work to my truck, I've had mine a couple years and noticed my hose is kind of dry rotted and I talked to Walley at FTE Diesel and he said some fittings may have backed off a little and is sucking air some where
 

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Air can do this with any system for sure guys, but; I would check the tank to make sure you didn't just get a tank of fuel with trash in it first... Start with the simple stuff first, like looking for signs of fuel leaks at hose connections, wiring system of new pump.

Now a few questions to help any of us that might be able to help figure this out and point you in the right direction...

Did you have a new larger suction leg added to the tank: Like a DrawStraw??? The DSV system of the DrawStraw brand is one of the best I have tried...

Next question would be where is the fuel pressure sensor of your guage, in line at??? Like right after the pump, or under the hood somewhere??? This would help in making sure to be looking from that sensor tap point backwards toward the tank for the problem-O's LOL

Bring everyone up to speed on your complete fuel system and where your fuel guage gets its reading from in this sytem... Then you also mentioned you never hear anything like the pump sucking on air or just starting to cavitate on the lack of fuel??? If not one different sort of noise from the pump, might want to check the power to the pump???

Check both the ground and the B+ sides of the 12 volt wiring to the pump... Another question, you still have the OEM pump and the fuel module exactly as it came from Dodge, in the fuel tank? If so, you still have power to that OEM pump as well???

That sort of thing would be really hard on the new FASS system your running, to be honest here, if you don't have the new DSV suction leg in the tank and new 1/2" fuel line from it to your FASS and 1/2" line on toward the CPS, I would be all over getting that reguardless of what you find to be the problem... If you have a new suction leg in the tank, I know you just made a long trip in this truck with no problem like this, but you may have had whom ever installed the new suction leg get trash in the tank and that has finally made its way to the suction point and stopped the suction for a short time and then the trash drifted off and into another area of the tank in the fuel for the time being, or you just have some really nasty fuel; but if you heard no noise differences when the pressure was lost, I would be all over the electrical connections first from the sounds of that...

This just my thoughts on all this with a few places to check/look, hope you find something here to help and if not by answering a few of the questions I have asked, someone else here will be in a better insight to help you figure this out I hope...

Look forward to reading what you find to be the problem...
 

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Discussion Starter · #4 ·
Jeb,
Thank you so much for the comments. Unfortunately this is why over my knowledge level. I had a diesel shop install it for me. Hell I was proud of myself for being able to do the EGR and EGR cooler deletes by myself with the help of the step by step instructions from this forum (thank you fellas).

Ok so I do see a hose running back into the tank. I have the H&S fuel rail plug at the front of the rail and it appears to have an electrical connection at the end of the fuel rail. I don’t know which hose is the draw straw. I have an electrical (auto meter) fuel pressure gauge on the pillar. Tomorrow in the sunlight I will look for a possible kinked hose and double check the clamps to ensure tightness.

I don’t think the info that provided is what you were asking about, but again I didn’t understand half of what ya wrote. It’s more than my mere mechanical brain can comprehend. I’m posting a picture of my FASS for whatever its worth.

Thank you again for taking the time to respond.

 

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The fuel lift pressure sensor won't be on the rail... Its going to be somewhere from your FASS to the CP3 which is your fuel injection pump... The DrawStraw will be installed in the fuel tank itself and you will have to drop the tank in order to inspect that...

Might need to go back where you had all this work done for them to have a look see at their work...
 

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I agree, if it was just installed 2 weeks ago, take it back, they will fix it, and ask lots of questions while you are there, where are the sensors etc.
 

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Discussion Starter · #7 ·
Yea wish I was home to have it looked at. I had it installed and left 3 days later for a 6 month work assignment in New Mexico. I checked all the lines as best as I could and I didnt find any leaks or kinks. I drove it until the low fuel light came on and put on a fresh tank of 32 gallons of fuel and the problem stopped.

I dove to EL Paso,TX and back on one tank of fuel and it ran perfect and the rail pressure was a steady 15psi the whole trip. Maybe I got some crap in the line last week?
 
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