Running out of fuel

[Brimmstone]

Okay folks this one is getting really,really weird. I've been having trouble for a while with the truck stalling out like it ran out of fuel. I have to stop and crank and wait, crank and wait, etc. You all know the drill by now. It had a mechanical pump that was working just fine for the longest time. Then all of a sudden it started this crap.

I got P!$$ED tonight and install a Mr.Gasket Blue pump from Advance Auto Parts and figured okay problem solved.

Now here is where it gets really weird. I bled the filter out by pulling the valve out of the pressure check point and turning the key on till fuel came out. I then put the valve core back in and shut the truck off and took it for a ride to test it out.

Both tanks were completely full and have been kept that way to rule a broken sender out of the equation. I know both senders are broken off at about 1/4 tank level. So I never let the truck drop below about 1/3 tank. I was cruising along and it started surging and acting like it was going to stall and after doing this for a few seconds as soon as I pressed the clutch it died.

I coasted into a parking lot and popped the hood to check and make sure I still had fuel pressure. I figured maybe it popped a fuse and lost power but I could hear the pump running. I grabbed my valve core tool out of the glove box and pulled the core on the filter housing. All I got was air for a bit then after about a minute it started pumping fuel out of the fitting. I started it back up and drove it home and it stalled again. I checked it and again the filter was empty or close to it. I'm running out of ideas on this one. Any suggestions would be helpful.

 

[MIDNIGHT RIDER]

Although new truck manufacturers don't provide them, an ABSOLUTE MUST, on a diesel truck, is an in-cab mechanical fuel-pressure gauge, plumbed in between the fuel-filter and injection-pump.

Even better is to have a second gauge between the lift-pump and filter.

This way, you have some chance to monitor what is going on.


That being said, does it pull this trick on both tanks, or only one ??

Do you still have the un-reliable electric tank-selector valve ??

I had numerous failures like you describe, until I gave up on electric valves and installed manual valves.


You definitely have something allowing you to run out of fuel and suck air.

I would pull the sending units out of the tanks and inspect them for a crack/break in the draw-tube.


Trace the fuel, from tank to filter-head for an air/fuel leak.


First thing to check, if you haven't already by-passed it, is the drain-valve on the water-seperator.




Another possibility is the O-ring inside one of the numerous plastic fittings that connect the plastic fuel-lines to the tanks and fuel-selector; this is one leak source that many never think to check.



Also, if you don't already have extras, get yourself a pill-bottle full of Schraeder valve-cores, and some metal caps, for those times when you drop the only one you have in the tall grass.

These can be picked up by the handfuls off of any tire-shop floor for free.




One other thing, are you absolute sure the filter isn't stopping up ??

 

[Brimmstone]

Okay to start Water separator was removed and replaced with a Racor filter unit before I got the truck and was then rebuilt when I replaced the engine. Yes I still have the electric tank selector for now. I know the sending units are cracked at about the 1/4 tank level and never allow the truck to get that low. I'm going to test for an air leak in the front tank lines by switching it to the rear tank and purging the whole system of air then driving it and checking it to see if it has air in the filter head again. If it does I'll have to inspect everything before the new electric pump. I'll probably install a fuel pressure gauge just after the new pump next week and install a second sending after the main filter and flip between them with a double pole double throw switch.

 

[Brimmstone]

Okay I just got back from Melissa and swapped the axle over to Dirtleg so it is on the next step of it's trip to Michael. The front tank section of fuel system is the issue because when I was running from the front tank it ran like crap and was bucking and spitting. I switched it to the reaer tank and within seconds it was running fine. I'll use the new electric pump to empty the tank out and then drop it to find the issue. At least now I have a general idea of where it's at.