Fixing fuel line advice -

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post #1 of 8 Old 11-12-2013, 03:30 PM Thread Starter
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1995 ZJ 
Join Date: Jul 2012
Location: Nashville
Posts: 18
Fixing fuel line advice

Hi all. I recently developed a leak in my fuel line post tank and pre filter and had some questions/wanted some advice on the process to fix the issue. To view an album with comments check here.

Problems: The plastic line for both the main line (R) and the return (L) have gashes in them.

Also, the bolts holding the skid on have some metal deposit on them so that they can't be removed with simple hand tools.

The fix seems simple enough, and I know taking it to a shop would be a pretty penny. So, my questions are as follows:

1. Can I fix the lines without dropping the tank using nylon tube? The space seems a bit tight and the boiling process seems like a PITA/iffy at best.

2. Re: skid plate bolts. If I need to drop the tank, what is this metal on the threads (from a welder or solder) and how could I go about removing it to get the skid off? [easy/medium/hard difficulty?]

3. Re: Fixing the lines. The OEM part numbers should be 52005108 (fuel supply rear on the R) and 52005110 (fuel vapor rear on the L). This would most likely be for tank to filter for the main line & to the connector for the vapor line.

Would it be better to purchase some nylon tube (~$20) and splice in the new with the old
Redo the entire line (tank-filter, necessitating dropping the skid & tank) with either nylon & the quick disconnects (OEM is around $30 each I believe), rubber fuel line & hose clamps [as mentioned in this post], or another option like steel braided line.

Thoughts and opinions are welcome and appreciated. I'm trying to determine my next steps and a lasting solution to this problem. If possible I'd like to DIY but I just moved to a new city and all my tools are back home. If I have to take it to a shop I will but I want to have decided the fix I want beforehand (i.e. #3) and tell them exactly what to do. If anybody's around Nashville and wants to help me out I'd make it worth your time.

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post #2 of 8 Old 11-13-2013, 06:44 PM
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1997 ZJ 
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Wow those bolts look rough

I think your best bet would be to purchase a nylon fuel line repair kit and splice out those bad sections. (Hopefully there's enough room to work up in there)
Because otherwise, you would have to get into dealing with those skid bolts. That looks a lot like welding slag on them. If you are feeling ambitious, I bet you could take an angle grinder and lop off the buggered ends of them and the nuts would just thread off... and then purchase more bolts. (DO NOT use a torch in there for cutoff!!!)
If you have the tank dropped, I would replace the whole works with steel line as a durable upgrade.

I did a quick search online and there are plenty of places that sell the nylon repair splice kits... prob. your best bet.

GL! Let us know how it turns out!

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post #3 of 8 Old 11-13-2013, 08:14 PM
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1998 ZJ 
Join Date: Sep 2013
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While repairing my fuel pump issue a few months ago, I noticed that main line had a kink in it right at the disconnect fitting at the regulator.

I had attempted to repair by cutting out the kink and reconnecting the line to the disconnect. No luck getting a good seal on it.

After seeing the prices of the plastic fuel line repair kits, I purchased some fuel injection fuel hose (rated for almost 300PSI) and replaced the entire plastic main fuel line, using the factory disconnects and some good clamps. No leaks, works great, and no worries about plastic splitting or kinking.

Your local parts store should have either the repair kit with tubing, some brass/metal flared splices without the hose, and/or the fuel injection hose.
You may just need the flared splices to correct your issue.

The BEST way is to drop the tank. Not sure what is on your bolt threads, maybe some sort of thread-lock. If you decide to drop the tank and have to deal with those bolts, take care when removing them, you don't want to damage the bolts or the threads. Clean the threads below the nut as best you can. Don't use the nut to clean them, as it could possibly seize and break, then you have additional issues.

Good luck.

1998 ZJ Limited 5.2L (upgrades in progress)
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post #4 of 8 Old 11-13-2013, 10:19 PM Thread Starter
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Thanks for your input.

Dropping the tank would be ideal and then just replacing the lines. However, a quick fix might necessitate a simple union in each line until I can get my hands on a grinder and suitable work space to have at those skid bolts. It's definitely metal on the threads and a couple of attempts at going caveman on it with a hammer/chisel have proven unsuccessful. I was also considering heating them with a propane torch for a hot second...but then reason kicked in. I think best case scenario I can grind enough off to remove the bolts and then pop some new ones in. Feeling up into the "frame" rail it seems like a similar configuration is on the top side (i.e. no head to the bolt just another nut on one long stud.) I'll have to do some looking to see where I can get replacements before grinding.

Bullwinkle, out of curiosity when you replaced your line do you recall the size of the stock line? I put a caliper on the main nylon line (R) from pump-filter today and got an outside diameter of ~.33 in which I believe would correspond to a 5/16 line. That solves one problem, however the vapor line (L) was ~.25 in and I don't believe parts stores carry fittings in this size.

Thanks for the luck Han would say, I'm gonna need it.
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post #5 of 8 Old 11-14-2013, 04:10 AM
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Location: Central
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Any idea how those gashes got in your fuel lines to begin with? I would bet it's rodents chewing on them and you can see the double incisor front teeth marks on them in your 1st photo. I live in the woods while having the squirrels, chipmunks, mice, and groundhogs do $5K worth of damage to my Jeeps! They just love to chew on plastic fuel lines, wires, hoses, etc.. No rats here, except the bushy-tailed ones which are the worst, but they'll do the same if you're in an area they reside in.

Part of the problem in repairing those plastic fuel lines is they're ID metric, at least on a 96 4.0. Also saw someone here go to the dealer to buy just the fuel line from the tank to the fuel filter and they wanted $100.

I finally aborted the quick disconnects on the filter after the squirrels chewed 2 in half. You may be able to get a metal barbed fitting in the lines if you heat the metal up first out from under your Jeep. While it wasn't the correct way believe I found a metal insert to go in the plastic line, like those used on some compression fittings/ice-maker tubing then put fuel injector hose with 2 small fuel injector clamps on the outside of the plastic line. Then just had hose connected to the fuel filter with double fuel injector clamps. As already mentioned having hose with quick-disconnects on each end may be the best solution but involves dropping the tank. Good luck!

BTW, I have plastic convoluted tubing on almost all my lines, hoses, and wires with it taped with good electrical tape to help prevent rodent damage. And real nice of the manufacturers to use sugar-based adhesive on almost all friction tape on wiring harnesses!
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post #6 of 8 Old 11-14-2013, 09:42 AM Thread Starter
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I agree with your critter hypothesis. The new place I moved to has about 10 assorted squirrels and chipmunks foraging about the yard all day every day. I know a good trick to keep them out of flower beds and such is to apply red pepper but I doubt dousing all my lines with hot sauce will be as effective. Hose protector might just be the way to go.

That is a little disappointing that the tubes are metric but hopefully I can work something out. Thanks for the ice maker idea for parts. I have been wondering (but highly doubt) if anybody makes a pressure fernco small enough to cover these lines. That would be ideal. I think a union with hose clamps is my best bet, at least in the mean time.

Also for future reference if anybody actually searches this down the road, I found an OEM parts dealer which has both the fuel and vapor line for less than $50. No need give the stealership any more of your money. Obviously confirming the parts would be wise but this is the same page I have in the parts manual (and they even don't list line #3 because ZJs only have the two running to the tank).
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post #7 of 8 Old 11-14-2013, 05:51 PM
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In doing some searching here's a 5/16" Napa coupling for nylon line and it's supposed to fit 7-9mm nylon line sizes. But your barbed coupling may also work. Since you can't really put heat to it with the fuel vapor you may be able to put the ends in a cup/jar of boiling/hot water to soften the plastic up some. As also mentioned heat the brass coupling up a little.

Good find on the fuel lines and a whole lot cheaper than what somebody quoted from the dealer.

I'll run the gamut as far as what I've down for critter/squirrel damage control. I live in a park and can't shoot while even the Gammo pellet guns with silencers are too loud. The squirrels love to chew the underhood insulation and take it home to their dens. Soaked it down with critter control spray with capsaicin, chili pepper you mentioned and the same product in mace/pepper spray. They still chewed/took it home and hope their little eyes burned like he**! Have also sprayed this spray all over my wires/hoses and loses it's effect.

Live trapped 9 gray squirrels out from under my son's car he used to have and turned them loose far away. Still didn't dent the over-population. Tried blocks of rat poison under the porch and they drug it out so had to quit that because of my dog/cat. Rat and mouse snap traps on the engines only caught chipmunk hair. They didn't want to go into an enclosed wood box with a 2" slot where I had a big rat trap baited with peanut butter.

Moth balls are supposed to be a good repellent but I can't stand the smell. Currently I'm dumping all our coffee grounds under my Jeeps and seems somewhat effective. But I park on all gravel where it doesn't show. The past 6 months I've had one packet of "Fresh Cab" tucked away in each engine compartment and it does seem to be effective as a rodent repellent. Sometimes I'll throw one under the rear but the scent doesn't last long out in the open/weather.

For years I've battled these critters and was thinking about getting one of these!

Good luck with your lines and the squirrels!
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post #8 of 8 Old 11-16-2013, 04:52 PM Thread Starter
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I'm going to put this here before I forget and in hopes that someone who searches this in the future can hit the ground running:

A 95 ZJ (and I suspect most others with the I6) have 2 lines associated with the fuel system: Fuel supply and Vapor return

- The vapor return line is approximately 1/4" and a nylon coupling for fuel lines will work on this line. (see Uniblurb's link above for pic)
- The fuel supply line is 5/16" BUT at the fuel filter the quick connects are different sizes. Tank side the quick connect is a 3/8" (5/16" line attached). Engine side the quick connect is 5/16" (5/16" line attached).

Most, if not all,part stores don't stock the tank-filter combination if you are looking to repair your existing line and not drop the tank via chop and replace with a 3/8" quick connect - 3/8" line. THIS IS BAD NEWS BEARS! You need to use your stock 3/8" quick connect to 5/16" line and heat up some new nylon. You can also get (or order this or its 90 degree cousin). Be warned, heating the nylon and trying to get it to fit is a royal PITA. (At least my attempts at it this evening failed miserably). The best solution, as many have mentioned is to drop the tank and replace with OEM parts or stainless steel lines or whatever else tickles your fancy.

Nylon Line Heating: So I've done a little research and Nylon's melting point is somewhere in the neighborhood of 500 degrees F. Boiling water is a chilly 212 deg F by comparison. Obviously you don't want to melt the line, but it does need to get warm enough to stretch a little. So some alternative methods for heating would include open flame (this can burn your line), heat gun (or hair dryer?), stove top, or special heat lamps. With these higher temp devices make sure to constantly rotate the tube to ensure even distribution of heat. It also should be noted that heating the fitting would be ideal so as not to create a strong heat-sink and thereby the nylon lose its plasticity/pliability. Results to follow.
Hair Dryer: doesn't get hot enough
Open Flame: must watch very closely or it will overheat and start melting your nylon/fitting
Boiling: I tried placing the end in boiling water on two occasions with no success. The end flared a little but never enough to go over the first barb on the fitting. The pipe was not strong enough to force on the fitting and buckled twice.

Solution: I ended up just going to the junk yard and picking up two of the tank-filter lines off old ZJ's that were still good and splicing one in. Cost me all of $1.75.

If you want to save yourself some trouble and get in a little preventative maintenance, do as Uniblurb said, and go pick up some conduit as a good first line of defense against pesky rodents nibbling through your fuel line/wires.

Last edited by Asouthern; 11-17-2013 at 09:28 PM.
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