air at the filter head

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Ok the liberty has been running a little rough for the last couple of months (poor acceleration and stumbling) and has never gotten the fuel milage that some of you have posted. I've only gotten 18-19 in daily driving since I bought it over a year ago and only 25ish on road trips to the beach. I was thinking the worse like bad glow plugs or god forbid a turbo going bad or even bad head gasket. I blead the fuel filter head and it had air in it, alot of air. I blead it a good 4 or 5 times before I saw any diesel come out and after that it was another blead or 2 before it was pure diesel with no air. The Jeep runs like it never did since I've owned it. Is it possible that it has had air in the head for over a year?

. Would this be the cause of my bad fuel milage?

Joe Romas · **Posted:** Tue Apr 19, 2011 12:43 pm

You sir could benefit from one of the thousands of threads about air in the fuel :SOMBRERO:

papaindigo · **Posted:** Tue Apr 19, 2011 12:51 pm

Including those threads about replacing the original factory head with the newer OEM version to fix the heater element plug if you have not already done so.

DynoPax · **Posted:** Tue Apr 19, 2011 1:24 pm

...and perhaps a little device known as in-line fuel pump? :pepper:

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Without doing an extensive search, where does this air actually come from. I accused my wife of running it too low on fuel lol. How will an inline pump help? Someone school me please. I've read several post about the stock head not being very good.

mikey1273 · **Posted:** Tue Apr 19, 2011 3:03 pm

Do you have the blue heater connector with the splice in the lines. that's one way to tell if you have the newer OEM filter head. The first design had a problem with the heater and it would allow a leak to develop at the heater's power connector. since the fuel system is under vacuum you don't always spot the leak, instead air gets pulled in to the lines more so than fuel gets out. any loose connection can let air in. air bubbles in the fuel that make it to the filter can get trapped and build up air over time being the filter is the high point.

If you don't have the newer filter its time to think about getting one.

all the info is in the Nob guide

Joe Romas · **Posted:** Tue Apr 19, 2011 7:58 pm

TennesseeCRD wrote:

Without doing an extensive search, where does this air actually come from. I accused my wife of running it too low on fuel lol. How will an inline pump help? Someone school me please. I've read several post about the stock head not being very good.

They used the same fuel lines from the tank foward as the gasoline KJ's :dizzy:

BUT and that's a BIG BUT the gasoline KJ has a intank lift pump that pressurizes the fuel lines. CRD's didn't come with a intank lift pump to presurize the line and are under a vacuum. The plastic o ring fittings back above the tank work well with pressure but leak air under a vacuum.

I still have the stock fuel head with no problems but I've had an intank lift pump for almost 5 years since the dealer gave me the famous "can not duplicate" story. I've had many diesels and my crd acted up in less then a mile after I bought it. Early thoughts on the fuel head's heater plug melting was because it was surrounded with air instead of fuel that kept it cool.
A vacuum fuel system will work fine if it's designed right but parts designed for a pressurized gasoline system that are on the shelf don't hack it :dead:

Joe Romas · **Posted:** Tue Apr 19, 2011 7:59 pm

TennesseeCRD wrote:

Without doing an extensive search, where does this air actually come from. I accused my wife of running it too low on fuel lol. How will an inline pump help? Someone school me please. I've read several post about the stock head not being very good.

They used the same fuel lines from the tank foward as the gasoline KJ's :dizzy:

BUT and that's a BIG BUT the gasoline KJ has a intank lift pump that pressurizes the fuel lines. CRD's didn't come with a intank lift pump to presurize the line and are under a vacuum. The plastic o ring fittings back above the tank work well with pressure but leak air under a vacuum.

I still have the stock fuel head with no problems but I've had an intank lift pump for almost 5 years since the dealer gave me the famous "can not duplicate" story. I've had many diesels and my crd acted up in less then a mile after I bought it. Early thoughts on the fuel head's heater plug melting was because it was surrounded with air instead of fuel that kept it cool.
A vacuum fuel system will work fine if it's designed right but parts designed for a pressurized gasoline system that are on the shelf don't hack it :dead:

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

Joe Romas wrote:

TennesseeCRD wrote:

Without doing an extensive search, where does this air actually come from. I accused my wife of running it too low on fuel lol. How will an inline pump help? Someone school me please. I've read several post about the stock head not being very good.

They used the same fuel lines from the tank foward as the gasoline KJ's :dizzy:

BUT and that's a BIG BUT the gasoline KJ has a intank lift pump that pressurizes the fuel lines. CRD's didn't come with a intank lift pump to presurize the line and are under a vacuum. The plastic o ring fittings back above the tank work well with pressure but leak air under a vacuum.

I still have the stock fuel head with no problems but I've had an intank lift pump for almost 5 years since the dealer gave me the famous "can not duplicate" story. I've had many diesels and my crd acted up in less then a mile after I bought it. Early thoughts on the fuel head's heater plug melting was because it was surrounded with air instead of fuel that kept it cool.
A vacuum fuel system will work fine if it's designed right but parts designed for a pressurized gasoline system that are on the shelf don't hack it :dead:

So in layman's terms, its pulling the fuel as apposed to pushing it. Will any $50 off the shelf inline fuel pump work to help fix this problem or is there a spacific one that should be used?

JL Rockies · **Posted:** Wed Apr 20, 2011 12:40 pm

<sigh>

flman · **Posted:** Wed Apr 20, 2011 1:16 pm

Once again, every one is telling this guy to do major mods, but no one has asked. "Did you change the fuel filter?" I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

mikey1273 · **Posted:** Wed Apr 20, 2011 6:13 pm

FLman is right it could be just a clogged filter. The op never said how old his filter was or if he had the newer design fuel head or not. If he has the new fuel head change the filter first. If it's the old style one then it might be worth changing that too since you get a filter with it from the dealer too. that is only if its leaking at the heater connector or any other place. If you unplug the heater and push the primer to create positive preasure and see fuel come out inside the connector even a little then it can pull air in from there.

the new fuel head requires a few wires to be spliced that's one way to tell if that's been done already. I can upload a pic of mine if that helps you to see what I mean.

If its only a filter they are about $30 at NAPA.

I have the new fuel head on mine and no lift pump at all. mine is fine. I changed my filter 20,000 miles ago and its about time to do it again.

spend the least you need to to get it to work. As long as I don't need and lift pump I don't plan to get one. why bother to do something that isn't needed.

If there are no signs of leaks then maybe its time for just a filter.

Greaser · **Posted:** Wed Apr 20, 2011 6:40 pm

I have been battling this air in the fuel issue, and still haven't figured it out. I've replaced the filter head, the fuel filter and cut out the fuel connectors near the tank and installed straight line, and still get air in the fuel. Hopefully you will have better luck than me.

Joe Romas · **Posted:** Wed Apr 20, 2011 7:05 pm

flman wrote:

I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

Consider yourself lucky twice. Maybe you should buy a lottery ticket :-)r

TennesseeCRD · **Joined:** Mon Jan 11, 2010 11:01 am **Posts:** 181

flman wrote:

Once again, every one is telling this guy to do major mods, but no one has asked. "Did you change the fuel filter?" I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

This guy changed the filter (napa) about 10K ago. May be time to change again? Looks like original or stock head.

flman · **Posted:** Thu Apr 21, 2011 6:43 am

TennesseeCRD wrote:

flman wrote:

Once again, every one is telling this guy to do major mods, but no one has asked. "Did you change the fuel filter?" I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

This guy changed the filter (napa) about 10K ago. May be time to change again? Looks like original or stock head.

I would change them both, if your filter is plugged, you are just asking for a way to allow it to suck in some air from some where. You filter has no real life span on it, it is all based on how dirty the fuel is that you have been pumping into the engine. I always keep one or two filter spares on hand.

Has the Jeep been running OK still, since you bled the filter? Maybe the guy never bled it right?

flman · **Posted:** Thu Apr 21, 2011 6:47 am

Joe Romas wrote:

flman wrote:

I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

Consider yourself lucky twice. Maybe you should buy a lottery ticket :-)r

I heard GDE mention more then once he has no lift pump on his 2 Jeepers as well :wink:

mikey1273 · **Posted:** Thu Apr 21, 2011 8:37 am

flman wrote:

TennesseeCRD wrote:

flman wrote:

Once again, every one is telling this guy to do major mods, but no one has asked. "Did you change the fuel filter?" I have 2 of these with no lift pumps so far, not to say I will never need one or two, but when Jeepers acts up, I put in a new fuel filter, prime it, and go happily on my way. :JEEPIN:

This guy changed the filter (napa) about 10K ago. May be time to change again? Looks like original or stock head.

I would change them both, if your filter is plugged, you are just asking for a way to allow it to suck in some air from some where. You filter has no real life span on it, it is all based on how dirty the fuel is that you have been pumping into the engine. I always keep one or two filter spares on hand.

Has the Jeep been running OK still, since you bled the filter? Maybe the guy never bled it right?

the owners manual puts fuel filter replacement at 25,000 miles. That is if you are always getting fairly clean fuel, which you don't always know, so if you start to have problems change it sooner. the fuel has to be sucked through that filter and a clogged one will cause it to starve when it needed the most fuel. I always have a spare at home and I take it on long trips just in case. I been lucky to get 20,000 + out of mine.

air at the filter head

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