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My crazy gas gauge!

Discussion in 'Computers & Technology' started by Tee, Jun 24, 2008.

  1. Tee

    Tee Gold Member

    For the car buffs (Kodiak)

    I have been driving a 2005 Pacifica for the past few years and I fill up the tank 3-5 times a week so I know that it holds exactly 20.2 gallons when the gas gauge is on empty. It's equipped with the mileage computer that tells me, down to the single digit, how many miles I can drive, and it's pretty accurate.

    So the past few weeks I have been noticing something strange. The gas gauge and the computer says I am empty, but when I pull up to the pump, I can only get 13 or 14 gallons in it. At first, I thought the pump had given me a "good deal".

    As I begun to drive it around Kansas, I noticed that it was dropping awful fast. It was then that I decided I must have a bad sending unit in the gas tank. So, I decided to not put much faith in the gauge and go by the odometer, until I could have it checked. I knew I could go about 440 miles on a full tank.

    Last week, while coming back from Goodland, It crept down to empty, but the gas in Goodland was like $4.10. It was only 3.77 in Wakeeney. I should be able to make it to Wakeeny with what I had in the tank, but decided to get two gallons just to make sure.

    Ok, so I made it about 10 miles down I-70 and FRRRRrrrrrrrrrrtt---Out of gas!! I was sitting there on the side of the road and I KNEW there was more gas in that darn tank!!! I looked underneath the car to check for a leak - no leak.

    So, I called a gas station in Park City- they brought me 2 gallons of gas for $12.00 plus a $60.00 delivery fee. That got me going.

    So, I stopped at the next gas station at Park City and got about 6 gallons-filled it up to over half tank. I then made it to Wakeeny where the cheap gas was. I stopped and topped of the tank but it only held another two gallons, which showed it on FULL.

    So I started down the road and 30 miles later noticed the gas gauge had already fell between full and half- eek!! NOT again!

    I decided to call Lopps while I was on the road. I told them the story and they were chuckling- they knew exactly what I was dealing with. He said" Let me tell you something about the Chrysler Pacifica fuel tank. They have a fuel tank like no other. It uses a saddle shaped tank which is basically like two tanks. When you fill it, it fills both sides when it goes over the hump and as you get below the hump there is a second fuel pump, a equalizer pump, so to speak that fills the other side. If it fails, you basically run on only half a gas tank.

    Well that's the craziest darn thing I ever heard, but it definitely explains my problem.

    This week, while I am on vacation, I am going to try and crawl under there and check the voltage up to the pump, and maybe see if I can even find the pumps, as there are two- a main pump and a equalizer pump.

    If anyone here has ever ran into this or knows where to find info that shows where the pumps are, what else to look for, I'd sure be interested.
  2. Highwayman

    Highwayman Gold Member

    Every now and then just take a corner too fast and get the car up on two wheels. The gas will slip over from one side to the other.
  3. Tee

    Tee Gold Member

    Heck, I do that already! :car2:

    KONQ RADIO New Member

  5. Army_of_One

    Army_of_One Banned

    Perhaps it has something to do with the fact it's a Chrysler...:lol:
  6. Highwayman

    Highwayman Gold Member

    Could be. I don't have that kind of problem with my GMC.
  7. Tee

    Tee Gold Member


  8. Army_of_One

    Army_of_One Banned

    It's O.K. You were a good little American and "bought American" so with the satisfaction that you "bought American" you get the headaches that come with an American made car. (that's actually made in Cananda I think)
  9. spike52

    spike52 Well-Known Member

    I believe they're assembled in the Windsor Assembly plant.
    That's in Canada.. :lol:
  10. wordsmythe

    wordsmythe New Member

    there is only 1 actual fuel pump, the other side fills off of a venturi from fuel flowing thru a second "pump" housing on the opposite side of the tank. there is probably a calibration update for the body computer, or the venturi side of the pumps is faulty, usually repaired by replacing both pumps. check your dealer, I'm sure they've seen this before.
  11. Tee

    Tee Gold Member


    I crawled under it tonight and could not see where the pump(s) are or should be. I couldn't even see the wiring. I definitely see why they called it a "saddle" tank. Apparently, they use the same tank on the allWD as the 2WD, so it has to "saddle" the drive line.

    So, looks like the dealer will get to fix it. Oh, and I did find this thread on the Chrysler forum about it the other night which seems to have some conflicting info about whether there are indeed two pumps or not. I was hoping I could save a few bucks, but looks like ...not.

    KONQ RADIO New Member

    From the link:
  13. Army_of_One

    Army_of_One Banned

    I'm just Teesing you....lol
  14. Tee

    Tee Gold Member

    Course, those Japanese vehicles aren't always all they're cracked up to be either....

  15. jeezeweeze

    jeezeweeze Active Member

  16. PacificaTroubles

    PacificaTroubles New Member

    Sorry for reviving this thread, but I really need the help!

    I bought a Pacifca yesterday and it has the exact same problem except the vehicle is hard to fill up after it conks out. It took me almost 10 minutes to fill one half of that tank. How was this problem resolved? Any idea on if the problem is the same as mine? Your help is appreciated. I've googled everything and I can't find a solid answer. Some people have said to replace the tank, some have said to replace the secondary fuel pump and sender unit, other people have remained silent on the fix. I need to get this thing for a reasonable price - going to the dealer kinda scares me because I'm so broke right now. Advice?

    Does anyone know how much it costs to replace the tank, pumps, and sending units in Canada? I think I'm going to have to save for this one...
  17. Tee

    Tee Gold Member

    Yes. I have the solution. Mine did exactly as yours...slow to fill the primary tank.

    After replacing all the fuel pumps, sending units and replacing the fuel modules, the problem still persisted.

    The problem turned out to be a $3 air inlet filter that sits atop one of the saddle tanks. It gets dirt and dust trapped in it, which in turn causing a vacuum, and will not allow the tanks to equalize. The tanks have to be dropped and this air filter (size of a silver dollar) needs to be replaced or blown out. The hardest part is getting to the filter.

    Since I sold mine two years ago, the buyer has came to me having the problem again. I explained to him how to fix it. So this is something that you will have to deal with every couple of years.
  18. PacificaTroubles

    PacificaTroubles New Member


    Thanks for answering my post - You rock!

    So this is my plan. I'm going to ask a friend to help me pull my tank. How can I test the equipment (fuel pumps, levels, etc) on the tank when it is off the vehicle? Is it as simple as attaching a 12v power supply? Should I bother testing them? I figure this would be the best time, but any advice is appreciated here.

    Also, I was looking at a diagram of the tank (which is attached to this post). I can't seem to find the $3 air inlet. Do you know where it is situated? I called the local Chrysler dealership and they said that there is no such valve. They also told me that all the pumps, levels, evap canister, etc will cost me about $1,400 just for the parts (not including a tank). I'm hoping that your fix is the one, but I'd be very willing to check out the other gas tank components to make sure it all works when it is buttoned up.

    Thanks again Tee! (or anyone else who can offer up some advice)

    Attached Files:

  19. Tee

    Tee Gold Member

    I don't think you can. From my understanding, it is all computerized and uses a matrix signal from both senders, averages them and then sends the signal to the gas gauge.

    I do not know where the air valve/filter it is situated. You might try calling Steve at Lopp Motors in Dodge City. He is the one the explained the fix to me after they figured it out on my Pacifica. 620-225-0271 Tell them it's Tim Trent's Pacifica that you are referring to - they know me. He will know what you are talking about.
  20. Sarape

    Sarape New Member

    Amazing to read about so many people having the same problems with their pacifica....
    Mine is a 2004, and also canĀ“t hardly put gasoline in it...

    PacificaTroubles, did you find the air inlet ? And did it solve your problem ?

    Really curious to know whether i can solve my problems using this method.
    Don't want to go to my mechanic and pay lots of money to remove and put back the gastank every now
    and then, without solving the problem :(



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