Air in fuel

Hey guys - for those who have not read my "build thread" I just finished installing EGR deleted manifold. While in there I rebuilt oil cooler and updated STC fitting, updated dummy plugs and stand pipes. Added a oil pressure sensor at oil cooler test port and fuel pressure sensor at fuel bowl test port. They are not hooked up to my CTS yet.

Truck had no start condition - unplugged ICP and she fired right up. Problem is with KOEO when fuel system is priming I can hear an air leak at the fuel bowl. I switched caps with my buddy and same condition. The only thing I can think of is the manifold sent to me was an 04 style which has the webbing/cross hatch underneath the neck. My stock manifold did not. When installing the intake the passenger head fuel line did seem to be tight getting around the neck but I was still able to connect to the fuel bowl as well as bolt in the guide/mount to the manifold. Is there anyway by having to gently "persuade" the fuel line it can be misaligned leading to this air leak? Not sure how sensitive these fittings are. Does anyone know if the 04 vs 05+ neck is slightly different which in turn the fuel lines may also be bent slightly different?

I will try to get the pressure sensor hooked up tomorrow to report psi. I used the sinister fuel pressure adapter kit which has a schrader valve and I bled the air out (thought I got all out as solid stream of diesel came through after air) and I still get the hissing noise from somewhere at the fuel bowl - but no fuel leak visible even after idling for 20 mins. Truck idled very smooth.

I do not want to drive like this as I do not want air getting into injectors, although I am hoping maybe a couple of WOT runs could solve it but think that may be wishful thinking. Any ideas would be appreciated.

Are you certain the air is in the fuel bowl and not somewhere else along the neck going to the manifold? I know Olly pressure tests his manifolds so it most likely isn't coming from there. Also, if you run it and then pull the cap, does fuel stay in the bowl or is it draining out?

Also, air will get purged through the injectors. as longs as there's adequate fuel pressure, the air in the rail shouldn't be a big deal. I mean if you consider air floats on fuel. The rails fill up from back to front since the motor sits like 5* downward. The air should hypothetically make its way to the front of the head but like I said, it will get purged through the injector and shouldn't be catastrophic. Have you felt around for air in the area?

It is def. in the fuel system you can hear the hissing stop as soon as the pump stops priming with KOEO. I am going to try aftermarket flex fuel lines to the front of the heads. No way I am pulling the manifold off. If that doesn't fix it I will buy a new stock housing and upgrade to blue spring and replace all orings etc. I am pretty confident fb leak is happening at the fuel bowl area.

Well after talking to a couple guys - I just need to drive this damn thing. No way to introduce air into the system post pump, so if there was air getting in it somehow there is no way the fuel bowl would be the culprit - there would only be a fuel leak at this location which I do not have. I have been told odd noises like the hissing is pretty normal until you drive the truck for a bit.

To be clear I was in no way putting down the manifold or service provided to me - I just was curious about the 04 vs 05+ neck for my own peace of mind. The manifold is mint and am not questioning it what-so-ever, only was questioning if the neck difference could slightly push off the fuel line out of alignment - which in all honesty I do not think it is doing.

I will report back in a little bit after she has some time back on the road.

Rob D said:

Well after talking to a couple guys - I just need to drive this damn thing. No way to introduce air into the system post pump, so if there was air getting in it somehow there is no way the fuel bowl would be the culprit - there would only be a fuel leak at this location which I do not have. I have been told odd noises like the hissing is pretty normal until you drive the truck for a bit.

To be clear I was in no way putting down the manifold or service provided to me - I just was curious about the 04 vs 05+ neck for my own peace of mind. The manifold is mint and am not questioning it what-so-ever, only was questioning if the neck difference could slightly push off the fuel line out of alignment - which in all honesty I do not think it is doing.

I will report back in a little bit after she has some time back on the road.

Click to expand...

That highlighted portion is basically what i was eluding to.

Keep in mind that the stock filter bowl has an air bleed orifice in it...if there is air getting in the system, a bunch of it will find it's way to the top of the bowl and be purged out that orifice, leading to a noise.

So I know a lot of guys are saying this is normal - figured I would take a video and post it to make sure you all still agree after watching. I upgraded to the blue spring today as well thinking maybe something was up with the regulator as the oring on the plunger/valve showed signs of wear. Did not help anything. Here is the video - click image to play and make sure volume is up.

What fuel filter is in the truck, OE (Motorcraft) or other?

Any difference if you put a stock cap on the bowl?

Did you ever get a pressure reading?

Motorcraft filter only. Bought aftermarket cap bc I thought mine was crap. Swapped with buddies stock one after the billet as well just to double check. Installed blue spring with no luck pressure stays above 55.

After doing the EGR deleted manifold and all the other upgrades in my build thread I was still puking coolant so truck is in now for a stud job. Will be having a fass installed with your RR so hopefully that settles it.