Did you confirm cranking fuel pressure? When you said 'like turned key off'..... so all the dash and electrical all shut off as well? Or the motor just stopped?

 

Motor just stopped ,all else normal , cranks but wont start .. Had a friend pump the primer while cranking and it started for a few seconds . Going to rebuild the primer pump and change the filter . Air is getting in

 

Check the ground connection of both batteries. Check the cables themselves for corrosion. Remember that you need good ground from the batteries to the engine, frame, and chassis. The engine to firewall ground near the master cylinder to the back of the head is often bad, and on the other side, the engine to the frame has deteriorated. Once you are sure you have good ground connections everywhere, you can look further. Remove all electrical devices from the diagnostic port and any other aftermarket electronics like radio, remote start, etc. Check to see if your ECM is still giving a good 5V reference by checking voltage at the MAP sensor (see attachment). If no 5V reference, your engine will not run and ECM is bad. The BCM is also suspect and new BCM's need to be programmed to your truck

 

The fuel lines to the filter look old . Do I have to order special hoses or can I just replace with generic hose ?

 

The fuel line from the driver's side of the engine to the fuel filter has a quick-connect on the driver's end. Best to use an ACDelco hose. Dorman might be good for a while if you're tight on money. You might have enough fuel line length at the fuel filter head to clip a little off of it and put a screw-type hose clam on it.

 

Rebuilt the filter head , new filter an new water in fuel sensor . still doing same thing . Will run if pushing the primer while helper turns the key , motor stops when I stop pumping the primer . ordered new dorman primer head . I am hoping this does it . Some of the fuel line fittings underneath look rusty .. I hope I dont have to replace them all . big project. does dorman make a line kit ?

 

Stay away from the Dorman stuff if at all possible, unless you are using it as a diagnostic apparatus.

 

which one is good . I cant find any OEM

 

The way I buy parts is to go to the GM auto parts lookup for your specific vin# and look up the part number. Use the part number on the Amazon website and the Rock auto website and that will likely give you the best delivered price.

I didn't make sure this was the correct part # for your truck but look at this: https://www.amazon.com/General-Motors-12642623-Fuel-Filter/dp/B00CMUCHHK

 

Installed new primer head . Still does the same thing . will only run if I pump the primer while someone else turns the key. How do I find the suction leak . does anyone sell a fuel line kit ? ( why dont these trucks have a fuel pump from the tank )

 

Possibly because of the amount of fuel pressure these more modern engines require.

 

Is the Dorman stainless steel line kit 919-845 any good . or is it better to use OEM GM 20832563 with rubber lines . Has anyone used the dorman ? does it fit and work without leaks and problems ?? Thanks again

 

You have now replaced the fuel filter head with an ACDELCO or GM OEM head? And if you continuously pump the primer bulb, the engine starts and runs for say at least 5 minutes?

Before I bought any fuel lines, I would do some testing to see if you can locate the problem area. See attached document. Your CP3 must have enough vacuum to pull fuel from the filter into the pump. There cannot be vacuum leaks between the fuel filter head and the CP3 inlet.

Then I would start with a jug of diesel temporarily plumbed into the fuel filter head. Put a length of clear plastic line in a vertical loop from the jug to the filter head and check the Schraeder valve test port to see if fuel is present. It should be. If not, continue pumping until it is. The clear fuel line is to see if air is continuously being drawn into the fuel supply when the engine is running. Pump and prime the fuel filter head and see if the engine starts and runs without pumping the primer continuously. If it does that tells me that the problem is somewhere before the fuel filter head. The next step would be to go to the quick connect line near the brake master cylinder and go thru the same exercise. If still runs fine, then go back to the previous joint and do the test again, and repeat all the way back to the tank. Of course, there is some work to do this but the cost is minimal.

If or when you decide to replace any fuel lines, make sure you get the correct part. I looked up your part number and expected that it would fit my 2008 LMM crew cab, long bed, RWD, and it does not. Your truck configuration is likely different than mine, so the easiest way is to use your VIN# when doing the lookup and verify this with the parts house.,

 

I just went to close the hood and saw wet fuel around the NEW filter head . I guess I got a bad one . I will have to get another one tomorrow . You cant make this stuff up if you tried

 

Get a Fass and call it a day. Had replaced the primer head three time before I went to a Fass 95. Best decision I ever made.

 

Installed AirDog lift pump - still the same.
installed new fuel pressure relief plug - same .
installed new fuel pressure regulator - same .
I have 1/2 fuel hose running from lift pump to filter head - same .
It will only run if I continuously pump the primer head

 

saw a drip in the return line by the fuel cooler .
I am replacing that line and the cooler .
This is baffling me and a few other people too .

 

Cant see the issue being the return side, deffinitely sounds supply side. Have you tried bypassing the filter head completely since you have the airdog now anyways?

 

Yes I bypassed the filter head and went directly from the airdog to the fitting by the schraeder valve . It would not start

 

I have also replaced the filter head , filter and water in fuel sensor .. twice

 

Just replaced the leaking return line . no change .
Ordered a fuel pressure gauge to check to make sure the airdog is working properly

 

I fought for months trying to find my air leak on my LMM. Replaced everything you did. Mine was sucking air from a rusted out fitting on the top of the fuel tank. I replaced that pickup assembly and no problems since. The easiest way to inspect it is to tilt the bed. Just be careful it doesn't scratch the cab when you lift it. I think it was remove 3 bolts, unclip two wires and loosen 3 bolts. Lots of instruction via google.
Good luck.