Engine/Transmission (1998.5 - 2002) Low Fuel pressure

[BWilson]

I have a 2001 that I upgraded the fuel system this past summer with a FASS system, new VP44, etc. I just filled up yesterday and now my fuel pressure is in the 4 psi range. It usually runs around 15-17 psi and drops to 9 or 10 at WOT. It's really cold here so I thought it may have gelled, so I changed the fuel filter today and it showed no signs of gelled fuel. Could the screen in the tank clog without anything getting to the filter? Should I drop the tank (it's full) or can I blow air through the line into the tank? I am planning on getting in the garage this weekend to thaw it out but any ideas would be appreciated. I have also noticed a smell of diesel around the back of the truck for the past week or so. This is accompanied by some hard starting, but only intermittently. I can't find a leak anywhere, but I haven't looked real hard either. One other thing, I noticed when I filled up the last two times, the tank is under vacuum so when I take the cap off, you can hear the air rush in more than I remember in the past. Are these all related or is a strange coincidence?



Thanks,

Brad

 

[rjrkihap]

A couple of thoughts:



Could the fuel lines be where the fuel is jelling?



Is your heater (at the fuel filter) working?



What type of fuel gauge are you using? Is the gauge and sending unit working?



Do you have the equipment to check the pressure at the FASS? A manual gauge right at the FASS can rule out a lot of issues.



Good luck



Ron

 

[DFerverda]

The vent is plugged, mine did the same thing. Here is a pic Joe Mc posted a couple years ago.
https://www.turbodieselregister.com/user_gallery/displayimage.php?&photoid=26370&width=0
The vent os on the left side of this picture. It can be accessed without dropping the tank, it is set in rubber and lube it with wd or some lube, be careful not to break off the tit, get it tuning and gently pry it up and remove, tear it apart and clean it good, put some oil on both the rubber and the vent and twist it back in.

I would also check to see if the inlet of the fass has a small screen, it may be restricted or if you have a prefilter before the fass it may be plugged.
Be careful of the fuel lines, if they look like Joe Mc's they will break if you mess with em. Here is his post installing the draw straw.

https://www.turbodieselregister.com/user_gallery/displayalbum.php?userid=8327&albumid=18623
Hope it helps.....
Edit///////
This will take care of the vacuum problem, If you are using power service for anti jell, make sure to get the new one for ULSD, the old ps does not do a good job on ulsd... ...

 

[jhoughton]

Mine has done the same as temp got down near 10 deg. I actually showed no pressure at 7 deg. I too thought that I had a fuel issue. It turned out that the baffle in the isolatore is too stiff when cold and would not move. Once the engine compartment warmed some I had normal fuel pressure. I know I had a fuel flow could hear it in the filler neck and the truck never hesitated.

 

[BWilson]

Thanks for all of the help. It turned out to be the sending unit. I have regular pressures using an old fashioned gage.