Will it explode?

kcleong18 · Post by **kcleong18** » 29 Sep 2005, 16:59

Hi everyone, I am thinking of doing some tests on my 'stuck' XM fuel guage this weekend and a silly thought crossed my mind. The fuel sender end is supposed to be a variable resistance and I am quite handy with a multimeter. So will the tiny current while measuring the sensor cause the fuel tank to explode??? Never heard of such a case and no harm asking but really like some assurance. Thanks

bxbodger · Post by **bxbodger** » 29 Sep 2005, 17:22

No, it won't-you'll live!!!

jeremy · Post by **jeremy** » 29 Sep 2005, 17:28

Your multimeter will function at about 9 volts but only actually puts out any current on the resistance settings. The actual current is tiny as there are resistors in series to get the correct reading. On the other settings the battery in the meter is in fact only powering the display system.
So use the meter as a voltmeter or indeed as an ammeter and you will be using the car's supply which will in fact be greater than the power used to measure resistance.
Jeremy

Post by **Peter.N.** » 29 Sep 2005, 20:42

Which way is it stuck? If its reading zero just short the connections together on the sender, it should then read full, if it does the sender is faulty if not you probably have a wiring fault or faulty gauge (unlikely).

a_seebo · Post by **a_seebo** » 29 Sep 2005, 22:10

But Jeremy, don't you think that he can use the Ohm meter as well to check the resistance of the coil? It will be 9 volt from the multimeter instead of 12 V from the car battery.

jeremy · Post by **jeremy** » 30 Sep 2005, 03:01

Yes I don't see any problem, The next question is can you get access through another hole and raise and lower the float manually? - or take the thing out to test it?
Jeremy

kcleong18 · Post by **kcleong18** » 30 Sep 2005, 07:26

Hi guys , tnxs for the feedback. The guage is kind of stuck midway as the previous owner hv emphasised to fill her up when the needle is at the halfway mark.Anything lower you may hv to do some pushing. Guage level drops to zero with engine off so will do some tests from the fuel sender end.
Bye everyone and hv a nice wkend.

lighteninguk · Post by **lighteninguk** » 30 Sep 2005, 17:09

took some time to work out what hv is, but seems to mean "have"
a tip kcleong.... try not to use "text" speak as you dont have to limit the amount of characters you use here (also note forum rules)

uhn113x · Post by **uhn113x** » 30 Sep 2005, 18:32

To summarise, the current through the meter is much less than the current through the goo-age when it is working normally, so no bang!
However, will it tell you anything useful? If the gauge is either permanently on full or not working at all. you do not need a meter - disconnecting and shorting the sender lead out will tell you if it is the problem.
If the unit is sticking, you will just need to take it out and have a look.
HTH

kcleong18 · Post by **kcleong18** » 07 Oct 2005, 06:24

Hi guys ,
What a relief that this forum is back! Kudos to those who work so hard to bring this back.
Now my tests on the fuel guage sender seems to indicate that the display is working so maybe the sender is stuck halfway. There is also some extra wiring piggyback to the 5 pin connector and so far have worked out that some fuel pump modifications had been done. Anybody here knows the pin connections for the plug? Appreciate some help. Thanks

NiSk · Post by **NiSk** » 07 Oct 2005, 10:08

Hi kc,

According to the wiring diagram i have, the pump is connected to pins 3 + 5 and the gauge to pins 1 +2 . the warning light (if fitted) is connected to pin 4.

Hope this helps.

//NiSk