Truck Dies... Vacuum on fuel filter?
 

Weekend before last I put gas in my truck and had to recover from that. I siphoned out the gas, replaced the fuel filter and cracked the lines to work the gas out. Long story short I got it running again. I also put in a couple quarts of 2 stroke oil. I filled the tank and ran it all last week and into this week with no problems. Tuesday night on the way home it started running rough. It would lurch like it was about to die and then keep going. It got worse all the way home. Yesterday when I tried to start it, it would idle rough and then died.

I opened the drain today on the fuel filter just to be sure diesel came out. Nothing came out at all. I took the top off which seemed really tight. It has diesel in the canister. Not sure if you can tell anything from looking at the filter but it looks clean and isn't dark or anything. With the top off the fuel drains. Once I put the top back on it doesn't seem to want to drain. I can hear the lift pump running.

Any thoughts on what is going on? It's acting like the fuel isn't flowing. Should I replace filter again?

Sometimes mine doesn't drain when I open the drain valve. If I loosen the filter top to let it vent, it'll drain all the fuel out.
What's your lift pump fuel pressure? Stock spec is 10psi minimum.

I'm not sure. Don't have a pressure gauge. I just replaced the lift pump last summer.

Fuel pressure test kits are available at most auto parts stores. The one that fits most GM systems also fit our Cummins.
If you have an old R12 Freon kit w/gauge, it'll fit onto the Schrader Valve on the injector pump too.
Pics in my Gallery...jes' click on Clunk, View Public Profile and find Gallery. It's on page 2.

I see the picture of the pressure gauge. Where would I connect that to get a pressure reading? Given my symptoms is the lift pump the most likely culprit? Last year when my lift pump went out the truck still ran.

The Schrader Valve connection to the VP44 is on the same page.
Well we hope it's the lift pump failed and not the injector pump.
You can turn the keyswitch On-Off-On-Off-On then look at the odometer for any trouble codes stored too.

Yeah checked the codes and got nothing but the P1693 which has always been there.

You also might fill up the filter housing 3/4 full to try to keep from getting lots of air in the fuel system.
You can bleed air off the injectors by loosening #1, #3, #4 & #5 injector fittings then crank the engine 10 seconds then look and tighten the wet fittings and crank again until all the wet ones are tightened or the engine starts kicking/trying to start then tighten any loose ones. A 19mm wrench fits the injector fittings.

Haven't had a chance to work on it until this morning. Pulled the fuel filter again and it is really tight going back on after the first turn or two. I pulled it out and reached down inside the canister. It feels thick and silty at the bottom. Pulled some of this crud out and it is this yellowish thick crud kind of like bearing grease and some black gritty stuff mixed in. I'm going to drain out the diesel from the canister and get as much of this stuff out of the bottom as I can. I'm hoping the feed to the injection pump doesn't come out the bottom. Where else can I clean to make sure I get all of this cleared out?

I cleaned as much of the gunk as I could out of the bottom of the fuel filter housing. Clunk, I cracked lines 1, 3, 4, and 5 and gave some cranks until fuel was coming out. I alternately tightened one line at a time and cranked until all lines were tight. The truck started up but it is still running rough.

I'm starting to think this might be an electrical problem. The weekend I had to recover from gas in the tank my batteries were dead. They will charge up but haven't been holding a charge well. I replaced one of the two with a new one. Today while I had it running I watched the volt gauge and it doesn't look right to me. It slowly fluctuated between the first white line and 14v. When I got on the throttle the voltage drops then when I go back to idle the voltage gradually goes back up. Alternator maybe? I pulled the other old battery out and ran it. No change. I pulled the main power cable off the alternator and ran it just on the one battery but it still is doing the same thing. And the volt meter is still not stable.