Solved Misfire '07 4.0 XLT

Car was running rough after short warm up, scan indicated misfire cylinder 6. Changed wires and plugs, car ran great. Two months later same problem,same cylinder. Changed cylinder 6 plug again, car ran great again. A few weeks later started running rough again. Scan indicated misfire cylinder 6 again and a fuel injector problem. Due to a recent health issue, i gave up and called my buddy who has a tow business. Amazingly he just met a certified Ford mechanic that retired after 28 years and was working on his own. I called him and he offered to come to my house and check it out. He checked the obvious things and scanned it with a high end device. Same codes appeared. He started the car and it ran normal for a few minutes and started to misfire. He decided since it ran good initially, it had to be the fuel filter. Sure enough it was almost completely blocked. He admitted that it wasn't a lucky guess, it is a common problem that started when Ford changed the fuel regulator and eliminated the fuel return line. The older 4.0 fuel rails were under constant pressure and any unused fuel was returned to the tank. Newer models have a return line for vapors only. Cylinder 6 is at the end of the line and gets starved first. If you ever lived in a house with low water pressure and happened to be taking a shower when someone flushed the toilet, you will understand.

Car is running perfect now and my MPG have improved. Finding this mechanic was a stroke of luck. He drove about 60 miles round trip fixed my car and charged me less than what the tow would have cost.

Every dog has his day!

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Yeah, this is the kind of post I like to see!

Thanks for taking the trouble to explain everything. Congrats on the resolution and more importantly, your new mechanic.

I see the filters are the same for the 4.0L as the 4.6L. It's not an item I normally maintain. It just seems so huge (compared to old carbureted engines), I couldn't imagine it getting clogged. Needless to say, it's on my parts shopping list now.

Thanks Again!

Great post, and great explanation! So many times people forget about the fuel filter because it is never seen, and it can cause so many intermittent problems. Hopefully, everyone reading your post will put the fuel filter on their next maintenance due list!

Yeah, and what's nice about changing Gen IV fuel filters is that NO special tool is required.

Fuel Filter Replacement

My '94 Town Car, winter beater, was leaking fuel, and it turned out to be the original filter rusted through. I decided to grab one at Rock Auto, since they're so cheap, and I can wait till it's mailed in. Figured I might as well grab one for the Explorer, and a couple other cars:


Started with the Explorer. Needed a 13mm Socket to remove three bolts holding some kind of heat shield on. Bolts went through the box frame, and were a bit corroded. No way to lubricate them, so they had to be ratcheted out every inch. Surrounded by sharp sheet metal, so it's a slow go. Then, got to the second heat shield. 10mm socket required to remove two nuts with fairly deep studs holding it on. Corroded of course, so another slow go. It's a bit tight up there between the exhaust pipe and frame. Fun's not over yet. The filter is held by two different types of clips, and talk about tight quarters... Ugh! You have to look at one of the clips very carefully to see how it's held in place, then wrangle it free with a screwdriver and not much room to work. Lastly, the obligatory gasoline trickling down your arm as you free it from the lines. I literally get a headache from strong perfume. Gasoline fumes are instant agony.

Went back together very quickly, but while I was under there I noticed transmission fluid dripping on the exhaust pipe and cross member. At first I thought it was the pan gasket, but the bolts were all tight, and I saw fluid higher up on the front of the tranny. Didn't figure out what it was coming from yet. Hopefully nothing serious.

Moved on to the Town Car, and replaced its fuel filter pretty quickly. My God, it's so rusty under there, it's depressing. I guess one more winter will be the end of it.

Hello
I'm new to the forum but I have s 2007 Explorer with 4.0. Where is the fuel filter and any threads on how to change it. I've searched but I must be missing something. Thanks in advance.

Toyboy883 said:

Hello
I'm new to the forum but I have s 2007 Explorer with 4.0. Where is the fuel filter and any threads on how to change it. I've searched but I must be missing something. Thanks in advance.

Click to expand...

See here: http://www.explorerforum.com/forums/showthread.php?t=271152&highlight=fuel+filter+change
The Sport Trac is the same process/location as the Explorer/Mountaineer, but pictures seem to indicate that they seem to have a little more breathing room under there than I recall the last time I did mine. I believe that the filter is a different product number for the 4.0 (motorcraft number FG-1083). Also, see here for a diagram from ford of the basic assembly/location for the 4.0: http://www.fordparts.com/Commerce/CatalogResults.aspx?y=2006&m=Ford&mo=Explorer#Search
Just select the first image.
Edit: I cross checked the filters and they both use the same model/size of fuel filter so no difference between the two.

Thanks for the info.

About your Town Car Ornery,

By the look of your receipt, you can just get another Ford with the 4.6L V8 when the Town Car dies!

Fuel filter change

Previously i posted a comment about about how i solved a misfire on cylinder 6 by having my fuel filter changed on my 2007 XLT 4.0 engine. It happened again, now i have multiple codes indicating random misfire cylinders 4,5,6. My health has improved so I'm back to do doing my own work. I will post a comment on leaking thermostat housings next so you will understand why I am back to doing my own work. Anyway the fuel filter is a pita to do without a lift, but not impossible. I found a great YouTube video that will show you what your up against. This is a dangerous procedure to do without a lift. You have to jack the right side up to get access and need a light source to see what your doing. If you decide to do it make sure you at least use a jack stand in addition to whatever jack you have and a light source that is safe around gasoline (explosion proof). You will be on your back, so position yourself far enough forward so the gas doesn't spill in your face. Even after relieving the fuel pressure there will be a substantial gas spill. Use a rag when separating the filter from the fuel line to prevent the gas from running up your arm. I was able to disconnect the inertia switch without taking the scuff plate apart, i just pulled the plastic cover out from the front exposing the switch. I was more concerned about the hidden clips holding the scuff plate breaking. The heat shield and bracket are simple to remove 13mm and 10mm socket are all you need. The clips on the filter are only difficult if you don't have a lift, because in my case i could only use my right hand otherwise i would have had to lift the car much higher. The outlet clip is easy the inlet (red clip) is a little difficult. I used a piece of wire to pull the filter towards me and then used a needle nose pliers to open it. I gently position one jaw under the bottom of the clip and the other above the clip and squeezed them together, it pops right open The clip release is V shaped with the open part facing out, the lower part has to be squeezed in to release the clip. the upper part is hinged and will swing up after you squeeze the lower part. The attached link/video will clarify things. http://www.youtube.com/watch?v=FN5IKl2QKGI