Fuel Gauge Problem

Greetings All,

I tried searching around the site to see if anyone had this same problem and I found that none of the mentioned solutions worked in my case, so I started a new thread.

I have a 2002 Explorer XLT, V6, 4 wheel drive, with a little over 170,000 miles on the engine. About a month ago I noticed that there were some problems with my fuel gauge reading.

Basically, what would happen is the fuel level reading in the instrument panel would drop from whatever the actual level is, straight down to past E. This triggers the "Check Gage" light because the system thinks that there is no fuel in the tank. I know this is not the case because this would happen as soon as I finish fulling up the tank completely. There is no fluctuation in the fuel level, basically, it will just drop straight down to past Empty (the needle is in the rest position).

When I start the car up, the actual fuel level shows, and then after maybe 10 minutes or so, the fuel gauge just drops down past E. This happens whether I am sitting stationary in park, sitting stationary in drive/neutral, driving at city speed (about 30 mph) or driving at highway speeds (65mph+).

At first I thought that there might've been sulfur deposits on fuel sensors or something which may have given the inaccurate readings. So, I have tried adding Techron / Fuel System Cleaners upon fill ups. I added 3 bottles of Techron on three separate fillups and ran the car at highway speeds (65-75 mph) so that it would cycle through the fuel system. No Luck.

Next I thought that it might be the fuel pump going out, but the car runs extremely smoothly and handles well. Its a brand new battery, new alternator and starter are all fine. The car starts up fine and doesn't skip/stall while running. So I am inclined to think that its not the fuel pump. Also, I have not received any Check Engine Light as of yet, and this problem has been occurring for over a month now.

If my thoughts about the fuel pump are incorrect, how would you know about a "dying" fuel pump?

With more than 170,000 miles, I imagine that the fuel pump may need replacement, but this is an expensive repair. Also, I am sure my mechanic can check the fuel pump, but I think that he would need to drop the gas tank (which is a bit costly by itself). I don't have the funds to have my tank dropped for no reason. So basically, I wouldnt want to drop the fuel tank unless I was sure that this would fix the problem.

Another possibility that I think is that I may have an electrical short somewhere. Or maybe a ground wire is broken, which was the case with my "Door Ajar" warnings that I used to get, but solved a few years back.

So, has anyone else had any experience with these faulty fuel gauge readings? What should I try before I have the fuel tank dropped and/or fuel pump replaced?

Thanks for your time.

Here is a very good link to help troubleshoot and a way to make repair/clean you sending unit. Besides cutting an access hole, dropping the tank is the other way. Your difficulty on dropping the tank is to know when it is actually near empty to avoid the excess weight.

http://www.explorerforum.com/forums/showthread.php?t=322730

fuel gage

Try a bottle of Techron or Seafoam to clean sending unit first.

Thanks for the link FordFool2. So this definitely sounds like a problem with the sending unit and not an electrical problem?

And ronwc, Thanks for the input. I've already tried 3 bottles of Techron to no avail, as mentioned.

mranderson214, same thing here on my 03. I have 212K miles on her and im sure its the orig unit. Here is my situation; grab a beer, its a story. I put LED tail lights in and suddenly the relay needed to be replaced with an LED relay. That's fine, I did it 4 years ago. My O.C.D. kicked in and I really HATED the sound that my signal lights made when I put them on (it sounded like a 1980's/early 90's GM signal). I had enough. So when I went in for an oil change I asked them to replace the relay. The guy did. It blew the relay or fuse or whatever it was right away (I still had the LED tails in). So I returned the old one immediately (as per the service manager) and he put the old one in. In looking for this he took out every fuse that was in the little panel and finally found the correct one and was on his way... Ever since then I have had the same problem as you. Ironically enough, I feel as though he didn't put it back in tight enough because occasionally the fuel would show the correct level- regardless of it being full or not. So it may in fact just be a fuse... BUT, it took him 25 minutes- NO JOKE- to find this fuse. Its under the dash in an obscene place. I know that I can get between 350 and 400 miles a tank so right now im just watching my mileage because at 212K miles, im not investing too much into her even though its been an amazing truck. So ultimately id look at replacing one of the fuses that is in that little group under the drivers side dash...

mranderson214 said:

When I start the car up, the actual fuel level shows, and then after maybe 10 minutes or so, the fuel gauge just drops down past E. This happens whether I am sitting stationary in park, sitting stationary in drive/neutral, driving at city speed (about 30 mph) or driving at highway speeds (65mph+).

Click to expand...

Based on this my guess would be an electrical connection that was affected by heat. I would guess that the fuel temp is not affected that quickly so the pieces inside the tank would be last on my list.
I would start with wiring and connections under the hood and body.
Maybe a cold solder joint on the cluster.

Do you have the display that shows miles remaining and is that affected by this?

[MENTION=70850]RKelly2233[/MENTION]: Thanks for the advice. Those are my symptoms as well. The gauge will literally drop from F to E or from 1/2 tank to E. Sometimes it takes longer to drop than others and sometimes it doesn't drop at all, like it gives the actual, good reading throughout. I was beginning to be convinced that it was the float in the gas tank so I was kind of preparing to have that and the fuel pump changed sometime in the next month.

I think I had checked the fuses under the drivers dash and under the hood before but it wouldn't hurt to check them again before I have the tank dropped and all that. Just to be sure, there's only one cluster of about 40 little fuses under the drivers side dash correct?

[MENTION=171001]2Trux[/MENTION]: Thanks for the reply. I thought that it was an electrical problem as well but everywhere I looked, things seemed fine. Sometimes it would drop and sometimes it wouldn't. I was beginning to think that it was the fuel tank's sending unit which means dropping the whole tank.

I took out the instrument panel back in July and checked for any broken/cold solder joints. Some looked a little questionable but for the most part they were all intact. Reconnected the dash and the same problem kept happening. I then tried to check wires coming from the gas tank under the body, but everything seems intact under there. So I'm truly unsure. Sometimes the gauge will literally drop from full tank to empty as soon as I pull away from the gas pump.

Also, I don't have the message center on my model do my it only shows the trip mileage and the odometer/mileage with the compass direction and temperature outside. I've become fairly accustomed to doing the math in my head though just in case the gauge acts up randomly. So I have some idea and get fuel when I know its at about 4 or 5 gallons left.

The fuel reading circuity is just a bit more complex than we might think. Ford built the circuit to operate in a couple of modes (fill and slosh). I think they tried to prevent the gauge from swinging around when the fuel sloshes. There is a TSB that is not exactly your problem but it contains a lot of good information that may help you troubleshoot.

http://www.justanswer.com/ford/0s0lh-tsb-05213.html

I always say do the cheap thing first, try a new fuel cap and filter. If thats not it then it might be the pump even though the car runs well the pump could have weak pressure test the fuel line to see if the pump is weak.

some models have an ac/dc converter that goes bad, it is located on the top of the tank, there have been post about it.

mranderson214 said:

[MENTION=70850]RKelly2233[/MENTION]: Thanks for the advice. Those are my symptoms as well. The gauge will literally drop from F to E or from 1/2 tank to E. Sometimes it takes longer to drop than others and sometimes it doesn't drop at all, like it gives the actual, good reading throughout. I was beginning to be convinced that it was the float in the gas tank so I was kind of preparing to have that and the fuel pump changed sometime in the next month.

I think I had checked the fuses under the drivers dash and under the hood before but it wouldn't hurt to check them again before I have the tank dropped and all that. Just to be sure, there's only one cluster of about 40 little fuses under the drivers side dash correct?

Click to expand...

Actually NO! I believe there is only 6 or 9 of them... If you look in your manual there is a diagram. They are big and chunky fuses. There are a few places for fuses on the drivers side and this particular group of fuses is one of the worst to find and work on (per 2 Ford mechanics). Its tucked up and deep against the firewall I believe. Its in the group with the signal relay I was trying to replace. I would go take a look at my book but I have my truck at my other house (basically an empty garage) and it is ripped apart. I just did the blend door, which to be honest was not as hard putting it in as much as it was taking apart the console. Also did the blower motor resistor which I think was harder (not as messy though). Let me know if you try to toy around with it. Since my truck is already ripped apart I might look at it tomorrow (sunday) because im in that 'fix everything' mode. After that I gotta find a way to replace one of the hvac bulbs... Keep us updated!

[MENTION=162080]FordFool2[/MENTION]: Thanks for the reply. I think I recall reading the TSB that you mention several times. If we're talking about the same TSB, its the one where they basically say there's a fault in the wiring to the fuel sending unit and the solution is to replace a wiring harness for the fuel pump/sending unit in the fuel tank area.

If this is indeed my problem, then I'll try other things in the meantime. Dropping the fuel tank is kind of my last resort as it's the most expensive and tedious from what I've been told several times. I'll def keep the possibility of that wiring harness in mind for when/if I end up getting the tank dropped in the future.

[MENTION=221463]RicketyExplorer[/MENTION]: thanks for your reply. I have tried to replacing the fuel cap in the past, twice already. But not since this problem started happening with the fuel gauge. I had the current fuel cap on for about a year and a half before the fuel gauge started to act up. The one I currently have on is one of those fuel caps with the lock on it. Do you suppose it can be the fuel cap?

Fuel filter is something that I currently have in the queue to get changed when I get my full tune up from my mechanic in about two weeks when I'm home from college. I'm kind of hoping that might fix my problem if its not a fuse because I really don't want to have the tank dropped just yet. While I'm at my mech, I'll have him test the pressure in the fuel lines as well. I assume that this is something that can be done without completely dropping the fuel tank and such?

[MENTION=80575]vipersinu2[/MENTION]: thanks for the reply. I think you're referring to the TSB about the wiring harness at the top of the fuel tank that goes bad. I'm hoping that's not my case though because that'll involve dropping the fuel tank and such. I'm trying to avoid having to do that just yet. Thanks.

[MENTION=70850]RKelly2233[/MENTION]: Thanks for your reply. I will recheck my manual. I thought there were only 3 main sets of fuses: the high current fuses under the hood in the black box on the drivers side. One under the drivers side dashboard, about 40 little fuses. And the last being under the passenger side dashboard. I'm definitely going to try this out and look for these fuses that you mention near the firewall under the dashboard. As many times as I've been under there looking for stuff and fixing stuff, I don't think I have ever seen anymore fuses so Ford must've done a good job at hiding them. I'll check the manual first though. Hopefully the weather gets out of the low 30's this week and I'm able to get under that dashboard and inspect it in person (I don't have access to a garage right now).

I'll give these fuses a try before advancing to anything else. I'm convinced it might be a fuse or electrical short; because from what I hear, when the sending unit goes bad, the gauge either stays at F or stays at E forever. My case is different. My gauge usually shows the correct amount of fuel when I start the car, then after driving it around for some time, it randomly drops to E. If I were to pull over and restart the engine when that happens; it would go back to the correct amount and then drop again after some time. It usually takes like 3 restarts or at most 5 to make it stay at the correct amount.

Thanks for the tip. If you can provide photos of the general location of these fuses that would be great. In the meantime, I'll be searching through the manual and hoping the weather gets out of the low 30s.

Thanks.

[MENTION=70850]RKelly2233[/MENTION]: I went under the dash and I saw the fuses you're talking about. They do seem like a pain to get to. I checked all the fuses with a fuse tester, except the ones that is on the top side of the fuse panel under the dashboard. I guess those are the ones you were referring to. This whole time I had the manual, I thought that those fuses were on the passenger side dash for some reason. So I checked the high current fuses under the hood, and the standard fuses under the drivers side dash. Next I'll try and test those in the group of 6-9 fuses that you mention.

Based off my reading of the manual, it seems that those are basically 4 relays and 3 open sockets listed as follows:
Relay 1 Flasher relay
Relay 2 Rear defrost
Relay 3 Delayed accessory relay
Relay 4 Open
Relay 5 Battery saver
Relay 6 Open
Relay 7 Open

I'm not sure what any of the relays listed might have to do with the fuel gauge but it's worth a try if itll save some money. Is there anyway to check relays without a mutlimeter and such? I heard somewhere that you can remove the relay and test it by shaking it gently and if you hear sounds/rattling then its bad. Is that true?

Thanks

Where u able to figure out what is wrong? I have 2003 ford explorer 4.6L (approx. 100k) where the gauge acts the same way as you describe. It will show correctly and then drop to empty intermittently while driving. This has been the case for the last 5 years.

[MENTION=148531]dwillie[/MENTION]: unfortunately I have not gotten this problem remedied yet.

I ruled out all fuses and relays that are easy to get to. I checked fuses under the hood and inside passenger compartment as well. Looked for any broken wires inside under the dash, and looked under the passenger side along the frame to see if any wires coming from the fuel tank were damaged and may be causing the problem. Everything checks out normal.

I read a sticky somewhere on here that mentioned that there's a fuel pump connector thats supposed to be near the gas tank. This connector apparently has problems and sometimes fails causing the inaccurate reading in our model explorers. This was going to be my last resort to fix the issue. I'm currently saving up to have my tank dropped so that I can have the fuel pump, sending unit and this connector replaced. I figure since I'll be having the tank dropped I might as well change out the fuel pump as well.

This may not happen for another few months but in the meantime, I'll keep checking anything else that I possibly can. Its been acting mostly normal recently but occasionally the gauge will drop down to E and sometimes while driving it will go from E back to its normal level. Lets just say that as a workaround, I've become a pro at my 15, 17 and 19 multiplication tables

If I find a solution, I'll post back. Similarly, if you find out anything, please post back.

Well, did you get it fixed? If not, why didn't you try the troubleshooting procedure I outlined? Time it and see if it's exactly ten minutes. That may be the exact amount of time your pcm takes to let the sloshing stop and starts the intermittent reading/averaging mode.

Shawn