Purge Air from Fuel System

Bovie · **Posted:** Sat Feb 24, 2007 2:57 pm

Can anyone give me instructions on how to do this? I know how on my old benz but no clue on the jeep.

Thanks

Goglio704 · **Posted:** Sat Feb 24, 2007 5:09 pm

Push the primer pump on the filter head about six times, open the bleeder on the passenger side of the filter head, close the bleeder, and repeat until you get only fuel from the bleeder. The bleeder is 11mm by the way.

Bovie · **Posted:** Sun Feb 25, 2007 9:02 pm

Thanks I'll try it out and post if their is any MPG gain from doing this.

BioCRD · **Posted:** Wed Feb 28, 2007 12:09 am

My Liberty had begun to "surge", a gentle ~300 RPM variation of engine speed, at about 45 -50 mph on level roads. OD lockout had no effect - the slow (about a 3 or 4 second period) up and down engine speed seemed as if the converter was unlocking/locking. The last couple of days, this behavior became less gentle, and quite jerky. Funny, it never happened except at 45 to 50 mph. Is this the dread "shudder"?

After purging the air at the bleeder screw as described, this surging/jerking has entirely stopped. An easy fix!

This forum really has some good info - thanks to all.

retmil46 · **Posted:** Thu Mar 01, 2007 5:06 pm

I had a thought concerning trying to chase down air leaks on the fuel system, and trying to correct them.

They have what is known as liquid electrician's tape, used it in my other hobby tinkering with electric vehicles, to weatherproof all the cable connections. It's akin to what they call "plastisol", the cans of colored goop that you can dip tools in and dries to a rubberlike coating.

Liquid electrician's tape is basically the same stuff, paints on with an applicator brush, dries to a rubberlike coating, and can be easily scraped or cut off if the need arises. Only kicker is, if I remember correctly, it needs something on the order of 12 to 24 hours to cure properly.

I'm wondering if perhaps slapping a coat of this over the applicable joints and hose connections (after they've been properly tightened) would help seal up the air leaks.

BVCRD · **Posted:** Thu Mar 01, 2007 5:21 pm

[quote="retmil46"]I had a thought concerning trying to chase down air leaks on the fuel system, and trying to correct them.

They have what is known as liquid electrician's tape, used it in my other hobby tinkering with electric vehicles, to weatherproof all the cable connections. It's akin to what they call "plastisol", the cans of colored goop that you can dip tools in and dries to a rubberlike coating.

Liquid electrician's tape is basically the same stuff, paints on with an applicator brush, dries to a rubberlike coating, and can be easily scraped or cut off if the need arises. Only kicker is, if I remember correctly, it needs something on the order of 12 to 24 hours to cure properly.

I'm wondering if perhaps slapping a coat of this over the applicable joints and hose connections (after they've been properly tightened) would help seal up the air leaks.[/qu

That might work. Would the connections have to be just super clean in order for this stuff to adhere? When I changed my fuel filter, I noticed that I was able to get another 1/4 turn on the hose clamps from what they were originally torqued to. I suppose with a vacum system, it wouldn't take much of a leak over time to accumulate some air. I haven't chased any connection back to the tank. Is there something down there that needs checking?

Joe Romas · **Posted:** Thu Mar 01, 2007 10:20 pm

retmil46 wrote:

I had a thought concerning trying to chase down air leaks on the fuel system, and trying to correct them.

They have what is known as liquid electrician's tape, used it in my other hobby tinkering with electric vehicles, to weatherproof all the cable connections. It's akin to what they call "plastisol", the cans of colored goop that you can dip tools in and dries to a rubberlike coating.

Liquid electrician's tape is basically the same stuff, paints on with an applicator brush, dries to a rubberlike coating, and can be easily scraped or cut off if the need arises. Only kicker is, if I remember correctly, it needs something on the order of 12 to 24 hours to cure properly.

I'm wondering if perhaps slapping a coat of this over the applicable joints and hose connections (after they've been properly tightened) would help seal up the air leaks.

How does it stand up to fuel :?:

I bought some years ago and applied it to the handles of some Channel Lock plyers and when I cleaned my tools using gasoline it softened and partially desolved it. The product may have improved in the last twenty years though

retmil46 · **Posted:** Thu Mar 01, 2007 11:45 pm

Well, it does stand up good against battery acid spray and corrosion. And I'm talking about a LOT of spray and corrosion - like 20 6 volt golf cart batteries inside a single box, wired in series for 120V.

The liquid electricians tape variety I've used is from a marine hardware store, might be a different formulation than the tool dip stuff you can pick up at most hardware stores.

Guess the only way to find out would be to coat some scrap piece with it and then expose it to diesel fuel.

oldnavy · **Posted:** Fri Mar 02, 2007 12:54 am

Man I have never had a problem with air in fuel and I am wondering if you guys have a problem from either under torqued or over torqued connections.

On another note the wife run the Jeep for a day on the bingo light, so I had to buy fuel in town. As luck would have it a local retailer has ULSD now on the far side of town from us, but it still was a thriller drive across town with the fuel gage dead on the red line as I left the house. :roll:

It took 19 gallons. :shock:

BVCRD · **Posted:** Fri Mar 02, 2007 9:44 am

oldnavy wrote:

Man I have never had a problem with air in fuel and I am wondering if you guys have a problem from either under torqued or over torqued connections.

On another note the wife run the Jeep for a day on the bingo light, so I had to buy fuel in town. As luck would have it a local retailer has ULSD now on the far side of town from us, but it still was a thriller drive across town with the fuel gage dead on the red line as I left the house. :roll:

It took 19 gallons. :shock:

I know what you mean. I was on I-70 where it ends out in Utah over Christmas, and there is not much in the way of fuel out there. 1 mile from the end of I-70, there is an exit that goes North up to Salt Lake, and I took it. Luck was on my side and thre was diesel there a couple of miles up the road. It took, 20.2 gallons to fill it. I didn't even mind that they were sticking it to me with thir prices. I wouldn't have made it that far, except for the last 9 miles before that, I had been in neutral and was coasting down the highway dropping down into the valley. My wife said next time it gets on 1/4, we are filling up. That last 1/4 tank really goes fast.

BLake · **Posted:** Fri Mar 02, 2007 9:50 am

oldnavy wrote:

Man I have never had a problem with air in fuel and I am wondering if you guys have a problem from either under torqued or over torqued connections.

On another note the wife run the Jeep for a day on the bingo light, so I had to buy fuel in town. As luck would have it a local retailer has ULSD now on the far side of town from us, but it still was a thriller drive across town with the fuel gage dead on the red line as I left the house. :roll:

It took 19 gallons. :shock:

The dealer replaced almost every part of my fuel feed system and I'm still getting air in the filter. I was looking at it yesterday and saw a bunch of plastic tee fittings and such on the return side that were not replaced. I'm going to dig out my retro, old school vacuum tester and see how the various sections hold a vacuum. I seem to recall the system operates at 4-5"Hg. I have a feeling something is loose on the return side and it lets the fuel drain back when shut off. Also found the fuel line routed wrong and was pulled tight against the EGR pipe to the FCV. Should have left it like that and my problems would be solved in a few months :evil:

...but I fixed it.

The mechanic must have messed up my fuel sender. It was one needle above empty, no bingo light, and it took 20.3 gallons. Nice job.

BVCRD · **Posted:** Fri Mar 02, 2007 10:53 am

BLake wrote:

oldnavy wrote:

Man I have never had a problem with air in fuel and I am wondering if you guys have a problem from either under torqued or over torqued connections.

On another note the wife run the Jeep for a day on the bingo light, so I had to buy fuel in town. As luck would have it a local retailer has ULSD now on the far side of town from us, but it still was a thriller drive across town with the fuel gage dead on the red line as I left the house. :roll:

It took 19 gallons. :shock:

The dealer replaced almost every part of my fuel feed system and I'm still getting air in the filter. I was looking at it yesterday and saw a bunch of plastic tee fittings and such on the return side that were not replaced. I'm going to dig out my retro, old school vacuum tester and see how the various sections hold a vacuum. I seem to recall the system operates at 4-5"Hg. I have a feeling something is loose on the return side and it lets the fuel drain back when shut off. Also found the fuel line routed wrong and was pulled tight against the EGR pipe to the FCV. Should have left it like that and my problems would be solved in a few months :evil:

...but I fixed it.

The mechanic must have messed up my fuel sender. It was one needle above empty, no bingo light, and it took 20.3 gallons. Nice job.

I feel for you. Isn't it true that for the most part, it isn't neccesarily the work being done, or the reflash, or whatever, but the workmanship that bites every time? The human element side of it comes into play a bit too much for my liking.

truckbouy2 · **Posted:** Fri Mar 02, 2007 12:24 pm

This could be a tip for all these air in the fuel system leakers. About 2-3 weeks after "The Princess" took delivery on her L'oiler she informed me she was smelling raw fuel. This little bus was a '05 with only 900 miles on'er. Came right from Auburn Hills. So I looked things over and didn't notice any obvious leaks. I guessed it might have just burped a little fuel on refill. THEN one day after she finished work she noticed a wet spot on the concrete where she was parked. So "The Princess" skinny'd under the Jeep and saw where it was dripping from. Back by the tank in the last plastic line set retainer. The return line had a ever so small defect in it so it would drip ever so slightly but only when parked for extended periods. So I pulled it out of the retainer and put a piece of neoprene around the fault with a hose clamp to hold it in place. Now the adventure begins... I have a good honest relationship with the guy who occupies the WALNUT paneled office at Rosedale Dodge and his service rep and they realize that IF and WHEN I bring one of the trucks in for service its the last resort. I took it in, the diesel tech looked it over and they ordered a new line set. So I took it home and about 2 days later the service rep called me and told me the parts were in so I took her jeep in for repairs. Well when the diesel tech looked over the new line set he didn't like the looks of it. For what reason I don't know and the rep told me they were going to reorder. I know the parts guys well also, so that afternoon my parts buddy called me and said that all the replacement line sets had been recalled and they were on back order as they were waiting on the NEW supplier. How they did it, I am not aware, but the parts guys got hold of the supplier and found out they had 9 sets made and they would ship one to Rosedale that day. So... "The Princess" got her L'oiler fixed no more leaks, drips, or fuel smells. The service rep informed me that if DC pulls out all the replacement inventory sometimes there COULD be a call back in the works but it is NOT always the case. He also mentioned if there is a call back they are always the very last to know about it. Good dealer support from DC isn't it. IF there is porosity in the return line it will suck air correct ???? "The Princess's" line set had a big enough flaw that it dripped. A small enough defect that would allow air in but only seeped fuel (as the return line is not pressurized) when you drove it the wind would cause the seeping fuel to dispurse under the jeep making it difficult to notice...Maybe ???

BVCRD · **Posted:** Fri Mar 02, 2007 12:47 pm

truckbouy2 wrote:

This could be a tip for all these air in the fuel system leakers. About 2-3 weeks after "The Princess" took delivery on her L'oiler she informed me she was smelling raw fuel. This little bus was a '05 with only 900 miles on'er. Came right from Auburn Hills. So I looked things over and didn't notice any obvious leaks. I guessed it might have just burped a little fuel on refill. THEN one day after she finished work she noticed a wet spot on the concrete where she was parked. So "The Princess" skinny'd under the Jeep and saw where it was dripping from. Back by the tank in the last plastic line set retainer. The return line had a ever so small defect in it so it would drip ever so slightly but only when parked for extended periods. So I pulled it out of the retainer and put a piece of neoprene around the fault with a hose clamp to hold it in place. Now the adventure begins... I have a good honest relationship with the guy who occupies the WALNUT paneled office at Rosedale Dodge and his service rep and they realize that IF and WHEN I bring one of the trucks in for service its the last resort. I took it in, the diesel tech looked it over and they ordered a new line set. So I took it home and about 2 days later the service rep called me and told me the parts were in so I took her jeep in for repairs. Well when the diesel tech looked over the new line set he didn't like the looks of it. For what reason I don't know and the rep told me they were going to reorder. I know the parts guys well also, so that afternoon my parts buddy called me and said that all the replacement line sets had been recalled and they were on back order as they were waiting on the NEW supplier. How they did it, I am not aware, but the parts guys got hold of the supplier and found out they had 9 sets made and they would ship one to Rosedale that day. So... "The Princess" got her L'oiler fixed no more leaks, drips, or fuel smells. The service rep informed me that if DC pulls out all the replacement inventory sometimes there COULD be a call back in the works but it is NOT always the case. He also mentioned if there is a call back they are always the very last to know about it. Good dealer support from DC isn't it. IF there is porosity in the return line it will suck air correct ???? "The Princess's" line set had a big enough flaw that it dripped. A small enough defect that would allow air in but only seeped fuel (as the return line is not pressurized) when you drove it the wind would cause the seeping fuel to dispurse under the jeep making it difficult to notice...Maybe ???

You may be on to something. I have noticed if I fill the Jeep real full, I get a leak out of the back, underneath somewhere. I always just blamed it on me, overfilling it. I never splashed any outside the rig, just if I got it REAL full. I would see drips on the garage floor after this. It isn't a continual leak, just at the gas station and whatever comes off the jeep in the garage. If I don't super fill it up, it won't leak. I always thought it was some kind of overfill tube or vent or something. Anyone???

retmil46 · **Posted:** Fri Mar 02, 2007 1:00 pm

There is a small vent/overflow line hanging over the back side of the tank on the drivers side. Looks like a black 3/8" hose with a white plastic vent fitting in the end. If you try cramming it to the gills and then let it sit, it will dribble some fuel down over the back side of the tank.

Easiest way to prevent this - when the pump cuts off the first time, don't try to cram any more in.

BVCRD · **Posted:** Fri Mar 02, 2007 1:12 pm

retmil46 wrote:

There is a small vent/overflow line hanging over the back side of the tank on the drivers side. Looks like a black 3/8" hose with a white plastic vent fitting in the end. If you try cramming it to the gills and then let it sit, it will dribble some fuel down over the back side of the tank.

Easiest way to prevent this - when the pump cuts off the first time, don't try to cram any more in.

Thanks. That was what I was thinking (hoping) was happening, but his post made me think. I wasn't too worried about overfilling the tank since it isn't pressurized like a gasser, but I guess it still needs some expansion room. It really started since that trip to Vegas over Christmas when we almost ran out in the middle of nowhere. I try too cram it full since my walking ain't what it used to be. Thanks again.

retmil46 · **Posted:** Fri Mar 02, 2007 1:35 pm

From what I've seen with ULSD, you're not really gaining anything by cramming - very little foaming going on. Just slow down the fill rate for the last 2 or 3 gallons, and when the pump cuts off that's pretty much all she'll take.

On the MB, when the pump cuts off, it up far enough in the fill neck to be visible (no bloody restrictor plate). Ends up with about a 1/2" of foam on top, which goes away in about 30 seconds, and the fuel level is still well up inside the fill neck.

Pablo · **Joined:** Thu Feb 02, 2006 10:06 pm **Posts:** 1201

truckbouy2 wrote:

I know the parts guys well also, so that afternoon my parts buddy called me and said that all the replacement line sets had been recalled and they were on back order as they were waiting on the NEW supplier. How they did it, I am not aware, but the parts guys got hold of the supplier and found out they had 9 sets made and they would ship one to Rosedale that day... The service rep informed me that if DC pulls out all the replacement inventory sometimes there COULD be a call back in the works but it is NOT always the case. He also mentioned if there is a call back they are always the very last to know about it. Good dealer support from DC isn't it.

I am beginning to see a pattern with the redisgned/recalled parts on back order:

1. tranny filters (wrong ones, recalled)
2. ball joints (redesigned on the kk, parts supplier switched on old lib)
3. EGR (redesigned)
4. Flow control valve (redesigned)
5. Torque converter (maybe redesigned?)
6. Software reflash of ECM/TCM
7. Per Mopar64, new tranny has been built for next year with better power levels (redesigned).
8. CCV needs to be redesigned.
9. Now fuel hoses...

How much money would have been saved if they had done all this right the first time instead of listening to bean counters? The positive is at least someone is still working on fixing this stuff.

BVCRD · **Posted:** Fri Mar 02, 2007 3:40 pm

You forgot BCM recall/reflash on 2006's.

truckbouy2 · **Posted:** Fri Mar 02, 2007 3:53 pm

All the Fuel Line Bundle issues on "The Princess's" Oiler took place in November of 2006.
And the line set was the steel set from the tank to the engine. There were no rubber/nitrile lines replaced, at least to my knowledge.

Purge Air from Fuel System

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