Help: losing prime

[CancerPipe]

Ok so first off I'm on the list for new injectors. Getting a little haze at idle. No fuel in oil or other problems. Did however have a leaky bleeder screw due to a crack. Pulled the filter head off today and put in new seals and new bleeder screw. Put it back in with a new filter and primed it. Got nice and firm and the truck fired right up and I let it run a few minutes.

Went to start the truck back up and nothing. So I put the test gauge on the test port and primed it back up. Started the truck and it holds positive pressure at idle but once shut down it bleeds off. It also bleeds off if you prime it and don't start it. I did open the drain plug in the wif for the first time ever. About to pull the inner fender and see if its leaking. Any other ideas?

 

[CancerPipe]

Ok so I took the inn fender out. I can pump to my heart's content and the primer won't get very firm but no visible leaks anywhere.

 

[Linden]

i had similar issues it was the seals this would probably take care of this
http://www.merchant-automotive.com/deluxeduramaxfuelfilterheadrebuildkit.aspx

i bypassed mine and switched to a airdog 150

 

[CancerPipe]

It didn't start doing it until after I rebuilt the filter head. I've had it back out and ran through it again. Everything looked fine. Still no luck. A few pumps and it fires up and runs fine. Shut it down and wait about a minute and it won't fire. I can watch the pressure drop as soon as I shut it down.

 

[CancerPipe]

Update. Lines running to and from filter head where cracked so I replaced them. Also got a known good filter head from a buddy who deleted his. Primer gets firm now. Truck fires up and runs, but still loses prime when shut down. Got a fuel cap and put a valve stem in it. Don't have a clue what it could be seeing as how it didn't start doing it until I took the filter head off last time. Also according to the dipstick I'm not making any oil.

 

[CancerPipe]

Bump. Pushed some air in the tank. Couldn't find any leaks. Found something strange though. Pulled the truck into the garage and shut it off. Pulled the filter for the hell of it and its only half full.

 

[Hole Shot]

Does your lift pump work ?

 

[tyrat]

i was gonna say fuel lines we had a dd that wouldnt hold prime had a hole in the lines and would collapse itselfs when given throttle

 

[CancerPipe]

Twin pumps are running on one stator at the moment. Just enough for 5psi. I'm honestly tired of messing with it. Been trying to get it to take some air pressure for a couple days.

 

[CancerPipe]

A friend of mine wasted the better part of the day helping me today. We've done everything either of us can think of. Did have a suggestion that it could be the high pressure relief in the rail. Can't find a leak what so ever. Won't run without the filter head/primer either.

 

[bullfrogjohnson]

You need to bypass the lift pumps and get it running and recheck your pressures. Stock should see around 4-6 inHG of vacuum at idle and 10-12 inHG at 160mpa. You can also apply pressure on the return line and block of the supply and pressure check the system for leaks. The spec is 15 psi for pressure checking. Use a hand vacuum/pressure pump with a gauge (mighty vac). If you have a high vacuum at idle there is a restriction in the lines. Little to no vacuum, theres an air leak. You have to check the system at 160mpa also because your idle vacuum may be in spec but when you crank the rail pressure up it can lead you to your gremlins

You can also add a UV fuel dye in the tank and let it run for a bit. Then pressure check the system and use a UV light to help spot a small leak.

I worked on a truck that had the half full fuel filter issue and it ended up being trash in the tank and trash made it all the way up to the FICM inlet and clogged up in the banjo bolt and partially blocked the fuel supply.

 

[CancerPipe]

Didn't get a chance to do anything this weekend. And can't seem to find my mightyvac. Went out to start the truck and move it so I could get my work truck out and it wouldn't start. Tried priming but never could get it to start. Primer didn't feel right it was firm, but never got hard and wouldn't go all the way down. Batteries are almost dead too, even though I drove the truck friday and saturday. 1.5 year old interstates.

 

[N8thegreatchevy]

Was there any solution found to your problem? I'm having the exact same symptoms.