Air in Fuel Line - But not at Filter Head

fatweasel · **Posted:** Sat Dec 03, 2016 10:20 am

Need advice - I am getting air in the fuel line somewhere.

Didn't find any visible leaks but decided to change filter head (about two days ago).

No leaks for 2 days after new filter head.

Then this morning had a long turn-over before starting. Checked primer pump and there is air in the fuel system.

Put a piece of clear tubing upstream of filter and I don't see any bubbles coming from the tank - but if it is a small leak not sure if I would see bubbles?

I took off the alternator bracket to see the hose clamp connection between the fuel hose and the fuel pump tubing. Again no visible leaks at the hose clamp.

I am at a loss for where to find the leak....

Suggestons/recommendations welcome!

joe_ · **Posted:** Sat Dec 03, 2016 11:46 am

fatweasel wrote:

Put a piece of clear tubing upstream of filter and I don't see any bubbles coming from the tank - but if it is a small leak not sure if I would see bubbles?

You may want to put the clear tubing downstream of the filter head, since it's a potential leak point as well.

fatweasel wrote:

I took off the alternator bracket to see the hose clamp connection between the fuel hose and the fuel pump tubing. Again no visible leaks at the hose clamp.

You probably aren't going to see anything either way, since a leak in this case means that air is making its way in rather than fuel making its way out.

fatweasel · **Posted:** Sun Dec 04, 2016 10:16 am

Changed out the line from the Filter head (out) to the intake of the pump.

Still getting air...

flash7210 · **Posted:** Sun Dec 04, 2016 12:50 pm

The problem is most likely between the fuel tank and fuel filter.

papaindigo · **Posted:** Sun Dec 04, 2016 1:52 pm

It's not totally clear from your post but reading between the lines I'm starting with the assumption that a) you have the 2n gen fuel filter head (blue heater plug cap on driver's side) and b) as you mention the primer bulb that your air is in the filter head. If so:
1. between the fuel tank pickup and the CP3 there are only 3 possible sources of air in the fuel - a) line from tank to filter head (most likely the 2 quick disconnects back by the tank although it's not impossible that there are pinholes in the line, make sure the rubber section of the line that connects to the filter head is not cracked); b) in the filter head (filter not tight, old inner filter gasket left on so double gasketed, leak points such as electric plugs/bleeder screw/primer pump shaft/fittings and hoses, WIF sensor on bottom of filter not tight); and c) like in hose to CP3 or in hose ends. After the CP3 fuel line is pressurized so leaks would be obvious.
2. if you are bleeding the fuel head properly (similar to bleeding brakes - watch SirSam's filter head bleeding video in NOOB guide) and getting air out then c) is not a problem
3. bleed head; drive for a bit; shut down; using dry paper towels feel all around the filter head for any diesel leak. Will be obvious on dry paper towel. If found the fix.
4. if no luck it's likely the 2 quick disconnects. To fix you have to drop tank and either a) cut the disconnects out and replace with marine grade diesel rated fuel line and clamps or b) install in tank fuel pump.

fatweasel · **Posted:** Tue Dec 06, 2016 10:06 pm

Thanks for the advice. I am thinking most likely the quick connects in the fuel line at the tank.

Does anyone know if the fuel line diameter at the tank is the same as at the filter head - I think 3/8" I.D.

The filter head is the new style and was just installed last week - so I am thinking that is not the most likely leak point.

I'll get some fuel line and plan to drop the tank this weekend.

Interesting aside: Local dealer called Jeep and discussed with CRD Engineer. Jeep engineer told him as long as no drive-ability issues/CEL not to worry about air in the fuel.

WWDiesel · **Posted:** Tue Dec 06, 2016 10:26 pm

I think the supply line at the tank is 3/8...

But if you are going to the trouble to drop the fuel tank, I would strongly recommend installing an in-tank fuel pump!!!
The absolute best way to ensure you never have air infusion in the fuel system ever again is to install an in-tank fuel pump like the Carter P76148M in-tank fuel pump or an equivalent!
Your Jeep is already factory wired to a connector under the back seat on the drivers side for the in-tank pump including a fuel pump relay in the Power Distribution Center and the ECM already has the logic loaded for operation of the pump!
(The fuel pump relay runs the pump for ~15 seconds when you switch the key to the ON position and then runs the pump continuously when you start the engine)
It is a fuel pump for a diesel like the ones used in the Dodge Cummins Ram trucks.
You will be amazed at how much better the engine runs and performs with the addition of an in-tank fuel pump!!!

Additional in-tank fuel pump part numbers: AIRTEX-E7181M, DELPHI-FG1224, MOPAR-5143160AA

A properly installed in-tank lift pump will ensure absolutely NO air infusion into the fuel system period! :!:

An in-tank lift pump puts the entire fuel system under a positive (+) pressure from where it first exits the fuel pump inside the fuel tank through all the fuel lines and fittings, through the fuel filter head, heater, and filter, all the way to the back of the CP3 injection pump.
ANY LEAK anywhere on the system will BE SELF EVIDENT and show up very quickly as fuel leaking out.
Air simply cannot get into the system while it is under 10-15 psig of pressure!!!

If you opt to do the wiring harness mod yourself, all you will have to add is two wires from under the rear seat to the top of the fuel tank. The OEM fuel line fittings are designed for positive pressure, not vacuum, and will work just fine with the in-tank pump install and will not require any changes...

These two links below will answer any questions concerning installing an in-tank lift pump and / or wiring it up properly.
http://www.auerbach.ca/kj/lift_pump/
viewtopic.php?t=26385&highlight=

Seth at Sasquatch Parts has both the fuel pumps and correct wiring harness listed on his web site, Link: > https://shop.sasquatchparts.com/
Link:> https://shop.sasquatchparts.com/product ... r-p76148m/

fatweasel · **Posted:** Wed Dec 21, 2016 1:26 pm

Ordered an in-line pump from Kennedy this week.

Will post results following install.

WWDiesel · **Posted:** Wed Dec 21, 2016 2:06 pm

fatweasel wrote:

Ordered an in-line pump from Kennedy this week.

Will post results following install.

Why not the in-tank pump, it is the best option?
Be sure the in-line pump you plan to install is a low pressure type pump!!! Need 10-15 psig, no more.
Being you are doing an in-line pump rather than the in-tank pump, you still will have to drop the fuel tank and replace the fuel line and fittings on top of the fuel tank as they are not designed to seal under vacuum and that is what you will have with an in-line fuel pump on the suction side... :roll:

If you do not replace the fuel line fittings on top of the fuel tank, you can still get air in the fuel being sucked in by the in-line fuel pump...

That is why the in-tank pump is the best option as it puts the entire fuel system under pressure all the way from inside the fuel tank to the back of the CP3 injection pump... :wink:

fatweasel · **Posted:** Fri Dec 23, 2016 9:03 am

I agree the in-tank option is best. I have already replaced the factory fuel supply line with hose and clamps at the tank a week or so ago when I started this adventure to seal up the air leak.

The Kennedy pump seems to be a good compromise. It supplies 2 to 4 psi and is a flow through design so if it fails I can still drive home.

papaindigo · **Posted:** Fri Dec 23, 2016 11:13 am

I'll agree an in tank pump will totally solve air in the fuel problems likely including any at the quick disconnects by the tank on the supply line. However, you may trade air in the fuel for diesel out of the lines if there are leak points. For example failure to replace a 1st gen filter head with a burned out fuel heater element before installing an in tank pump will simply trade air in the fuel from the leaking heating element for diesel dripping out into the engine bay thru the now pressurized leaking heating element. My point being that installing an in tank pump is not automatically a total solution.

camo · **Posted:** Fri Dec 23, 2016 11:42 am

fatweasel wrote:

Thanks for the advice. I am thinking most likely the quick connects in the fuel line at the tank.

Does anyone know if the fuel line diameter at the tank is the same as at the filter head - I think 3/8" I.D.

The filter head is the new style and was just installed last week - so I am thinking that is not the most likely leak point.

I'll get some fuel line and plan to drop the tank this weekend.

Interesting aside: Local dealer called Jeep and discussed with CRD Engineer. Jeep engineer told him as long as no drive-ability issues/CEL not to worry about air in the fuel.

I had a leak like that on my sport. I just got rid of the quick connects and installed the hoses directly to the pick up unit with small clamps. It worked perfectly with no electric pump involved.

mass-hole · **Posted:** Fri Dec 23, 2016 12:26 pm

papaindigo wrote:

I'll agree an in tank pump will totally solve air in the fuel problems likely including any at the quick disconnects by the tank on the supply line. However, you may trade air in the fuel for diesel out of the lines if there are leak points. For example failure to replace a 1st gen filter head with a burned out fuel heater element before installing an in tank pump will simply trade air in the fuel from the leaking heating element for diesel dripping out into the engine bay thru the now pressurized leaking heating element. My point being that installing an in tank pump is not automatically a total solution.

Leaking diesel is much easier to spot than air though.

WWDiesel · **Posted:** Fri Dec 23, 2016 3:43 pm

papaindigo wrote:

I'll agree an in tank pump will totally solve air in the fuel problems likely including any at the quick disconnects by the tank on the supply line. However, you may trade air in the fuel for diesel out of the lines if there are leak points. For example failure to replace a 1st gen filter head with a burned out fuel heater element before installing an in tank pump will simply trade air in the fuel from the leaking heating element for diesel dripping out into the engine bay thru the now pressurized leaking heating element. My point being that installing an in tank pump is not automatically a total solution.

At least then, any leak on the system will be self evident, easy to spot or find and then can be repaired!!!! :rockon:

fatweasel · **Posted:** Sat Dec 24, 2016 10:39 am

Got the Kennedy pump in place this morning. Seems like a well built, high quality pump - machined body and heavy.

Wired the power to the fuel pump relay under the rear seat.

Kicks on for about 20 seconds when ignition in the accessory position and stays powered up if the ignition is running.

Primer pump gets firm when the pump kicks in. Still gets soft after shutdown and sitting for a while.

As stated above, if fuel starts leaking out under pressure I should be able to find/repair the leak now.

Air in Fuel Line - But not at Filter Head

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