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Ever since I've had the truck, it's only had to barely crank once to start the engine. Now it has to crank 10, 15 sometimes 20 times before it will start. It runs fine after starting. I have a two year old Blue Chip VP44, a new lift pump and good fuel pressure and have hand over handed the entire fuel system looking for leaks. This includes: injectors, supply lines, return lines, banjo-bolt o-ring seals, fuel line steel tubes to hose connections and have detected no leaks. I have no codes showing. A fellow Cummins owner thought it might be as simple as a faulty fuel cap not venting and drawing a negative pressure on the tank, causing the fuel to syphone back to the tank from the return line, loosing prime.Any ideas?Thanks.

Well after doing the new trubo swap .. and the 50 hp DDP injectors I have had a hard start issue . Replaced all the o ring on the injectors twice .. new injector tubes twice .. o rings on them twice . Tightened all connections , replaced the line from the filter to the VP with a big line kit . ... still air is getting back in and draining back . If the truck sits for more than 2 hrs it takes 3 cranks to start . Before it never did this with the OEM stuff . I am at my wits end . yes I searched , yes I did the baby powder , yes I parked it up hill and down hill ... If this cant be fixed I am lost . Banjo on the back of the head tight , t fitting tight . Battery's are good , VP is new , raptor 150 is new . Fuel PSI is 19 idle 17 driving 16 wot . Key on pump primes for 2 sec gauge reads 19 psi ... crank no start until i crank 3 times . Once started it will fire all the time , just wont after it has been sitting .

I put this together today since it is probably the main problem 12v's face. Air leaks can be hard to chase, especially with solid lines that you can't replace with clear rubber lines. You can but you have to buy fittings. All of the fuel from the lift pump to the injection pump should be at a pressure of ~26psi, so you can easily use clear hose in places to track air intrusions if you have all the right fittings. Hoses can get hard, get cut, and crack which is the main purpose of using as much steel line as possible on the fuel system. Any fittings with copper washers may not be seating correctly and need new washers. Some of the main things you want to check first are: [*]Bleed screw on top of filter [*]Fuel filter gasket and proper installation [*]Fuel Heater gasket and housing (cracked) [*]Hose clamps If you have recently done something such as removing the return lines or taking off injection lines, you should double check all of those and make sure the washers on the return lines are in good shape. When you have all the air out and are just trying to bleed it, you may also have to loosen an injector line. When you see fuel coming out, tighten it back down. If it is too tight when you are doing this, it will build very high pressures and spray all over the place, so loosen them maybe 1 revolution from being tight. Then you can crank the engine over while holding down on the pedal about 1/4 throttle and it will start up and try not to let it go over 1500RPM when it starts as this is not the greatest on an engine that has no oil pressure for the time being. Once it does start, keep it around 1200-1500 to keep it running and purge the remaining air out of the system. When it smooths out, it should idle smooth and your good to go. Check all your fittings to make sure they are not leaking fuel. http-~~-//www.youtube.com/watch?v=u1C8e5Q1l2E