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LX Hatch Fuel Guage ??

Started by _LXChev366_ , Aug 27 2007 11:19 AM

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5 replies to this topic

#1 _LXChev366_

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Posted 27 August 2007 - 11:19 AM

I have read the sticky above about fuel guages but I dont think my problem was answered... my guage works... but when the tank is full it only reads 3/4 and after about 200 kms it reads about 1/8 th above empty. I have done a rough L/100 average and it gets 14L/100km (std 308/trimatic 3sd). So I am guessing that I am only using about half the fuel in the tank. I am not game to see how far I get before it runs out. Knowing my luck, it will run out on a busy road with a truck up my arse.

any ideas on how to fix??

edit.. its a SLR/SS type guage cluster (orange needles)

Edited by LXChev366, 27 August 2007 - 11:21 AM.

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#2 _sstorana_

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Posted 27 August 2007 - 01:44 PM

LXChev366

Do yourself a favour and take your cluster to an instrument specialist. You will probably find that the voltage regulator is kaaput..
If you take it to these guys they can check and recalibrate the cluster so they are accurate agian and it's usually less than a $100..

cheers
Mick

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#3 Dangerous

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948 posts

Location:Adelaide, SA
Joined: 14-November 05

Posted 30 August 2007 - 01:30 PM

It's probably because your fuel tank is not earthed. They are just clamped between the floorpan and the straps, and when dirt and dust gets in betweeen the tank and the floor, the earth resistance gets high, and your gauge reads low. If you have access to a multimeter, check teh resistance from tank to car body. It should be very low, eg a couple of ohms at the most. Fuel sender unit should be around 10 ohms at full, and 73 ohms at empty.

Two things to do which should help.

(1) Rip the dash out and run an earth wire from the tin regulator on the back of the dash to one of the 5/16 bolts on the steering column bracket (not one of the larger breakaway capsule bolts - that's naughty), or another nearby good earth. This will help all of your instruments work better. The instrument cluster only has one common pissy little earth wire, and one small earth screw up to the left of the headlight switch. Neither are big enough to handle all the loads on the instruments, especially when the park lights get turned on.

and then

(2) jack the back of the car up, get yourself a bit of wire and one or two small hose clamps. Put one hose clamp around the metal fuel line where it comes out of the tank, and tighten it over one end of the wire so that teh wire makes good contact with the bare fuel line. Attach the other end of the wire to a good earth (eg tek screw through the floor, or something similar).

That should make your fuel gauge work OK, or at least better.

Mick, it's unlikely to be the regulator. They mostly fail in short circuit, which makes all teh gauges read high, and eventually cooks the gauges. They can short in open circuit, which means none of the three temp, oil, fuel gauges works at all - but this is rare. I've never seen one that has a fault which causes a low voltage output, and if it did, it would affect all three gauges.

Edited by Dangerous, 30 August 2007 - 01:34 PM.

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#4 _LXChev366_

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Posted 30 August 2007 - 08:35 PM

Thanks for the reply's.. I almost forgot about this post doh. :rolleyes:

Yep I suspected an earth problem... I was just curious if this was a common problem and had a sure fire fix. I will report back once I have attempted the fix.

Thanks again.

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#5 _LXChev366_

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Posted 01 October 2007 - 07:20 PM

Well I finally had a go at this today... I attached an earth wire at the tank... no change (tank is full at the mo) I removed the guage cluster and ran an independent wire from the voltage reg mounting screw to an earth... no change.
I just happen to have 2 other guage clusters ( 1 x SL and 1 x SLR) and tried them.. the SLR Cluster worked and the SL cluster sent all the guages to over full (i turned off the ign when I saw that of course, so volt reg is stuffed)... so I changed the volt reg from the SLR cluster over to mine... hey presto works fine. Go figure!!!