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Fuel gauge behaves strangely after car has been driving on LPG 700 1989

posted by  someone claiming to be Rob A on  Thu Apr 11 05:16 CST 2002 [RELATED]

The fuel gauge of my "new" 745 is acting strangely. It is rather unreliable and goes down on acceleration and up on braking (or is it the other way around - I'm not quite sure anymore...).

The PO had the car converted to LPG many miles and years ago, and I had the LPG system removed a few hundred miles ago. My suspicion therefore is that the fuel tank has not been filled completely for at least a few years. Could that have messed up the sensor in the tank, and might things just get better as the sensor gets some "exercice"?

Any other suggestions?

TIA

Rob








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    Fuel gauge behaves strangely after car has been driving on LPG 700 1989

    posted by  Rtilghman on  Thu Apr 11 11:52 CST 2002
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    I don't think its your sender assembly itself, but rather its mounting in the tank. I replaced my sender about 4 months ago when the power cable rotted off an dfoudn that it was overly sensitive to movement afterwards. I surmise I just mounted it off a little bit.

    The tank has a... can't remember the name... mini-tank in the middle of it that you can see if you pull your sender and lok in with a flashlight. The minitank is basically just a walled area (2.5"-3" high) in the middle of the tank with an opening up front to let gas slip in. The funtion is basically to reduce fluctuation by preventing gas from slamming forward and backward as you accelerate and decelerate. Also serves to keep the fuel around the sender arm (where its sucked up) and prevent starvation when the fuel level drops.

    I would suggest pulling your sender and examining it. If it looks like crud and the arm (that regsiters fuel level) seems shot replace it. If not, replace teh fuel screen (the baggie thing on the end of teh arm), tighten down the bolts at the pre-pump (do you have a pre-pump or just one pump on the '89?), replace teh O ring on the outside of teh tank, and remount the arm in the tank. Be caeful when you remove the sender... it DOES fit out the opening, but barely... you will need to spin it slightly and keep an eye on the arms to make sure they don't get bent, etc. FYI, be sure to check the electrical pick-up on the outside of teh sender and the sender ground cable while your at it. The latter is located just inside the driver's side rear wheel well inside the boot.

    good luck,
    rt








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    Fuel gauge behaves strangely after car has been driving on LPG 700 1989

    posted by  someone claiming to be adrian on  Thu Apr 11 05:25 CST 2002 [RELATED]

    Rob,
    I don't know the answer to your problem but I was wondering what you are doing with the LPG system. Do you still have it around? If you do, would you like to get rid of it? Let me know.

    Adrian
    adrian148@go.com








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      Fuel gauge behaves strangely after car has been driving on LPG 700 1989

      posted by  someone claiming to be Rob A on  Thu Apr 11 06:04 CST 2002 [RELATED]

      Sorry Adrian:

      I'm afraid its gone already. These things are quite easy to find here (in Holland). Let me know if I can be of any help.

      Best,

      R








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        Easy to find? 700 1989

        posted by  someone claiming to be adrian on  Thu Apr 11 07:24 CST 2002 [RELATED]

        Hey Rob,
        Where abouts are you located? Can you get the LPG systems for free or priced low? I'm in the electric/hybrid car club at school and everyone in the club has done something different to their car to increase the gas mileage. One of my buddies hooked up water injection system on his Omni and gets 42 m/g and another friend tweaked his 78 subaru brat to get 39 m/g. I thought it would be great to convert my 88 240 to LPG seeing that its earth friendly (which is what the club is about-cleaner burning vehicles), plus I would then have something to brag about when it comes to "car talk" during our meetings.
        Thanks for any info,
        Adrian








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          Easy to find? 700 1989

          posted by  someone claiming to be Rob A on  Thu Apr 11 21:24 CST 2002 [RELATED]

          Adrian:
          I'm in Europe, in The Netherlands (The Hague to be precise). I gather that you're in the US so unless you own a substantial amount of UPS stock the shipping would just kill you. This stuff is heavy - I'd guess some 100 pounds plus.
          R







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            Easy to find? 700 1989

            posted by  someone claiming to be mechanic on  Fri Apr 12 03:35 CST 2002 [RELATED]

            LPG rigs can be found just about anywhere for sell cheap. Flea markets, garage sells, want ads. I bet you could check a number of companies that sell propane on the local market and find 5 or 6 complete used rigs for sell. Especially in rural communities with agrigculture equipement.

            I have seen them go for 1000 but then again most seem to be going for 250 or less.

            I use to run a 100 gallon tank LPG system on my old pickup back in the 70s and early 80s. I think LPG was about 10 MPG but cost about $0.40 a gallon. I had not modified the engine to high compression or changed the timing because I ran it on gasoline and LPG. One plus for LPG is the engine will last forever! So will sparkplugs which even with the cheap plugs back then would last 90000 miles.

            Also the engine oil would last forever(figuratively speaking)The engine runs so clean that when I changed the oil at 5000 miles it still looked new with very little discoloration.

            Of course the downside is it is kinda a dangerous fuel to use and your system has to be maintained in perfect condition.







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          Easy to find? 700 1989

          posted by  someone claiming to be mechanic on  Thu Apr 11 07:42 CST 2002 [RELATED]

          To get any benefit out of LPG you have to raise the compression ratio of the engine. Nice thing is if I remember correctly, LPG has a octane rating around 100 or so.

          I use to have an old conversion book about LPG that was written for farmer equipment. It was very thorough about what has to be done.

          If you were to just attach the LPG you can expect to loose about 4 to 6 mpg. But with the octane rating you can experiment with compression, ignition advance, short duration high lift cams.








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    Replace the fuel gauge sender and be done with it. 700 1989

    posted by  someone claiming to be JohnB on  Thu Apr 11 05:23 CST 2002 [RELATED]

    Chances are the whole thing is corroded after non use.
    You can fool with it by removing it and checking it, but if I went to the hassle of removing it I'd replace it with a known good one. You should be able to get a good used one for peanuts from a junkyard.







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