ok thanks i'll probably try it tonight or tomorrow if i do need a pump where would be a good place to get it from? should i be worried its not reading oil pressure when cranking? one of my buddys said that it cuts the power to everything but the idiot lights when the starters engaged

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i hooked up a mechical oil gauge and im not getting any oil flow at all so i think the oil pump has locked up or the gear has spun off we'll be tearing the front of the engine tomorrow to see what happened,

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i hooked up a mechincal oil gauge still reading 0 i think the oil pump has locked up or the gear/nut spun off so we'll be tearing the front plate ect off to see what happened

 

your not going to see much oil pressure while cranking. if i remember right it doesnt even show on the gauge until a second after the engine starts. the duramax is more of an oil volume engine then a oil PSI engine. at idle it is not too uncommon to have as low as about 15 PSI when warm. i would not be too wearied about oil pressure unless it stays low when the engine starts. also the dash disply will worn you when the PSI is too low

 

i dont even get any oil flow out of the hole where the sending unit is when cranking and its full of oil i changed it today thats what worries me. i didnt try to crank it with out the FPR plugged in i guess i'll do the tomorrow and if it starts and the oil pressure dont come up within 2-4 sec i'll shut it down

 

i just tried it with the FPR unplugged still no start, its not holding a prim ether if i let it sit 1 min or so it takes a pump and a half to get rock hard again im starting to thing my CP3 is gone i just need to get a scanner out here to confirm it. i also put pressure to the tank no luck and couldnt find any leaks any ideas fellas?

 

i think it would be a good idea to replace the rubber hose on the output of the filter with a clear one so you can look for bubbles. any air in the line it will be hard to prime the CP3 and you will not build pressure. the CP3 cannot pump air so it will never start like that. i would take care of the priming issue before worrying if the CP3 is bad or not. the CP3s are a lot more reliable then the LB7 injectors. chances are, its still good.

the bleeder screw on the top of the filter housing is known for leaking, the primer bulb can also leak. sometimes the filter housing even develops a hairline crack.

if you are able to pressurize the fuel tank with about 5 psi and prime the filter and try and start the engine while maintaining pressure in the tank this may get it started.

 

ok my dads the one thats worried about the pump. i just rebuilt the filter housing i"ll pick up a clear hose tomorrow should i change that plastic bleeder screw with a bolt of the same size? if so should i slot it with the grinder like a flat head screw thanks again 2004LB7 you've been a great help

 

i dont think the bleeder is a common bolt size that will fit snugly. i was however able to find a allen head bolt (dont remember if it was metric or inch) that i wrapped a lot of teflon tape on that i use for one of my filters that seems to work fine. i of course never loosen it when i prime the filter and it seams to work fine. i do have a lift pump that helps prime the filters and keep any air out if there is a small leak so that may be why it works for me.

i dont think you need to slot the bolt for a flat head screwdriver. a small socket or an allen wrench will work just as good.

there is commercially made solutions to this issue if you can wait for shipping:
MA Aluminum Bleeder Screw For Fuel Filter Head
Duramax Fuel Filter Aluminum Bleed Screw, Nicktane
PPE Billet Aluminium Air Bleeder Screw 5130810
Merchant Automotive Aluminum Bleeder Screw

 

im hoping the air leak where ever it maybe is my problem anyway i wasnt able to get a clear hose today. ill order a screw and try again with it and a clear hose and see what happens

 

have you tried pressurizing the tank while starting?

 

yes it didnt even try to fire and i wasnt able to get the hose and order the screw today