Fuel issues!! truck shaking, fuel filter light on

[Woodturner Nate]

Background;

'96 PSD, 2 tanks, I just replaced the fuel filter, glow plugs & relay, and starter. Yeah, lots of stuff going wrong at the same time. I replaced the fuel filter because my girl ran one of the tanks dry and stalled out the truck. It started back up after a few minutes of cranking when she switched the tanks over. The filter was nasty, but not as bad as some pictures I've seen. It looked like it was covered in a thin gray grease. Anyway, after replacing the filter, the fuel filter light on the dash came on & went off a few times when I drove around to do some errands today. I thought nothing of it, as it was driving fine. I figured it was working out some air out of the line after replacing the filter--the bowl was only 2/3 full or so when I screwed the filter down. Meanwhile the rear tank was still empty.

I proceeded to go on a longer trip, with a steep uphill of a few miles on the interstate. About halfway up, the truck started shaking, the light was on, and it lost all power. I turned the flashers on and pulled over, thinking I had gotten something in the fuel filter, or water or something. The "water in fuel" light did NOT come on, but I figured I'd try the fuel dump lever which lets it drain any water in the fuel bowl. It made a hiss, like it was full of air, and seemed to do fine for several minutes more driving, then the same thing. Same hiss when I flipped the lever back & forth.

After four or five times stopping & doing the same thing, I finally got going downhill, and was able to coast off the interstate to an Exxon station, and filled up. For a while, it acted fine, then the same thing going back up and over the mountain.

The last time it purged air, I decided to flip over from the front to the rear tank.
No more power loss for the remainder of the trip, but the fuel filter light remains lit. Is it coincidence that changing from one tank to the other seemed to fix it, or is there air getting sucked into the line from one tank to another?

Should I have filled the fuel bowl up and overflowing when I changed the filter?? Do I need to change the filter again to see if maybe running the one tank empty just washed a bunch of junk into the fuel pump and clogged the new one??

WTF IS GOING ON WITH MY TRUCK!!!???

[Woodturner Nate]

I thought I'd post an update, as apparently I stumped everybody. This morning, I drove the truck ~50 miles or so to work, and had serious problems about halfway through. I stopped at a parts store and got some Power Service "diesel 9-1-1" additive to try and remove any water or gunk that was in the fuel bowl or lines. I poured a little right in the fuel bowl, and had much better running. I had to purge the air from the line once more and crank for a while to get it to run again, but after that, much better running truck.

I took it to a place in Culpeper VA that is a diesel fleet service ctr, and got good info. The master tech told me what I basically knew; under acceleration or going up a long grade the fuel pressure dropped, triggering the fuel filter light. He said it would read normal when running steady, but when you would accelerate, or stomp on it from the start, it ran less than 20psi.

It had a P0340--camshaft position sensor malfunction stored in the computer. So, I have a leak at the fuel pump, and at the rear tank sending unit, which could account for the air in the lines, but that low of a psi drop means more than just a bunch of crud on the screen, so I need a new fuel pump. DAMHIKT.
The good news is that all the injectors passed the cylinder contribution test, so I know what isn't wrong. Pretty good for a truck with 393K and 7 of the 8 original injectors.

So do I have to remove the bed to drop the tanks or what?? Maybe it'll be easier to just lift the bed anyway; anybody got a link???