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Discussion Starter · #1 ·
Hey guys,

My fuel gauge stopped working recently. Well, it works when the tank is full - and then once i run through some petrol it starts to drop, and then just stops reading and the gauge drops to zero for the rest of the tank.

Took it out, and tested it against the gauge - earthing the sender on my wing mirror. As expected, gauge shows full when sender is fully up, but as i move the arm, it starts to go down, slowly and then just drops. Thinking the sender was at fault, i bought a new one from Heritage. The original was VDO with a black float, but the new one is a slightly different product, with a big white unit covering the mechanism and a white plastic float. Dimensions all look the same, i assume it's just a cheaper replacement.

The thing is, this sender seems to show exactly the same symptoms on the gauge. It only works near the top of the arm's swing.

Thought the new one would fix it, but it doesn't look like it.

Any thoughts? Cheers, Patrick
 

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Have you a multimeter?
With sender removed, connect the meter from the sender case to the sender terminal.
Should read about 73 Ohms Empty and near 10 Ohms Full. See if the reading changes smootly from end to end.

If the sender measures OK, I would have to guess the voltage stabiliser/vibrator (on back of gauge) is faulty in some way.

Speedy Jim
http://www.nls.net/mp/volks/
 

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Discussion Starter · #3 ·
Need to get a new fuse for my multimeter, but will do as you have suggested Speedy Jim.

How are heritage with returns if it's as new?
 

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Discussion Starter · #4 ·
Set my multimeter to 2000 ohms and reads around 300 when the tank would be empty, and 0 when tank would be full. The readings are smooth throughout the range of motion.

What does that mean, that the sender is fine? This is the new sender btw, will take the original VDO sender off and test that too.

Cheers, Patrick
 

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300 Ohms is 3X (or 4X) too much resistance for your stock gauge. Methinks they sent the wrong part.

By coincidence, this new sender produces the same symptoms, but I suspect the old sender was simply defective. See what its resistance reads.

SJ
 

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Discussion Starter · #6 ·
I have got the older sender in, and it reads high 8's when full, and only increases for a very short distance before cutting out. So from this i'm reading the old sender is dead, hence only gave me a reading when the tank was full.

So this new sender, it's from heritage and says "Fuel gauge sender unit '68-" on the packaging. Looks right, and fits right?
 

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Right, the old sender is dead.

I've no idea why the part they sent is incorrect, but from the Ohm reading it is not right. Should have a max resistance of 83 Ohms.
 

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Discussion Starter · #8 ·
Right, i have emailed Heritage about this, and they have tested their other senders in stock.

"I took a random selection of two senders from the shelf they both gave similar readings to the one you have received. We had 50 of these delivered in September last year, only 14 left now and we have had no returns. I must assume that these readings present no problem. Unfortunately we have no Beetles here at the moment to check an in situ unit. Have you checked/swapped the voltage regulator, double checked the wiring and as a last thought is the body of the unit definitely firmly earthed when fitted. If you happened to have such things you could try connecting an earth via various resisters, because it could be the gauge has coincidentally gone faulty."

A very professional response in my opinion, i've never had to deal with Heritage in this kind of "techy" manner.

The new sender is in, and having used about a quarter of a tank, the gauge is reading steadily at the empty line (before the red reserve). Unfortunately i didn't have the new sender in while the car drank that fuel, so i don't know if the gauge went down gradually.

Could this be the voltage regulator for the gauge? Would that give these kind of symptoms?
 

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Wow! This is a 1st class mystery.
Cheers to Heritage for going the extra mile (km).

I stand by the resistance spec of 73 Ohms but there may be something else going on here. Any chance that the multimeter doesn't give an accurate measurement?

There are several different designs of the stabiliser, making testing of them very difficult. If you're up for it, order a new one.

Anyone you know with another Beetle you could exchange parts with as a test?

SJ
 

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Discussion Starter · #10 ·
There is a chance that the multimeter isn't accurate, it's a cheap one. Can i ask if this would make a difference:

Was testing drain on battery by setting the leads between earth cable and battery -ve terminal (but had key turned one click, so blew the 200ma fuse in the multimeter). Couldn't find a replacement quickly, so fitted a 2A fuse. Seems to work fine for voltage, and the drain on battery was down around 12ma. Any thoughts on that?

Unfortunately i don't know anyone else with a bug :(
 

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It's possible that incident damaged the meter innards.
If there is an electronics parts store handy, maybe purchase a 100 Ohm resistor to check the meter with.
 

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Discussion Starter · #12 ·
Nice idea, i'll ask around. If not, i guess i can pick up another multimeter (maybe one i can take back if the readings match)...

I'm going to purchase a used regulator off a vzi member, see how the symptoms compare. I just find it weird that the old sender went, and a replacement just doesn't work. I find it unlikely the regulator went at the same time as the sender?
 

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Discussion Starter · #14 ·
Right, well!

Empi pervert was great and sorted me out with a used voltage regulator. It made absolutely no difference to the working of the new sender. So, i took my old VDO sender apart and found the problem, the wire had snapped about 1/5th of the way along. It looked to have been repaired previously too. So i removed a section of the wire, and twisted them together to complete the circuit.

So now although i have about 3 turns missing on the sender, it works! Bottom end reads about 9ohm, and top end reads around 70ohm. Fitted the old sender back into the car and low and behold, it works. Although it reads about 1/4 tank too low.

So, the heritage senders are all wrong?
 

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removed a section of the wire, and twisted them together
WhooHoo! Very resourceful.

Hard to say about the Heritage parts. In any event, the one they sent you did not work correctly.

Glad you sorted it.

SJ
 

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Discussion Starter · #16 ·
Thanks :p I have contacted Machine7 about their senders, otherwise it will be a thread in the wanted section!
 

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Discussion Starter · #17 ·
No response from Machine 7 yet. I have put up an advert in the wanted section for an original VDO fuel sender, if anyone has one!
 

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I have had exactly the same problem, on my original VDO sender unit the resistance wire wore through at about the middle of its range which meant the gauge would only register from full to half full and the it would suddenly drop away.

I then bought a replacement sender unit from Heritage, and like you it would register full when the tank was full but then quickly drop away to empty.
I checked the resistance range of the sender unit and at full it was 0 Ohms and empty it was 300 Ohms. I then compared this with the resistance range required to make the gauge register from full to empty, using a variable resistor in place of the sender unit.

The gauge required and resistance of about 8 Ohms to show full and about 70 Ohms to show empty.

So I spoke to heritage about this and asked them what the resistance range should be for their sender units and the person I spoke to said " I don't Know" which was dissapointing. They also said that they sell a lot of sender units and haven't had any problems.

This left me confused thinking that it must be my gauge that is at fault, but having read this I now think there is nothing wrong with the gauge as it seem to be in line with the resistances Speedy Jim is quoting. I therefore think that the reproduction sender units that heritage sell are not compatible with the original VDO gauges.

I am now on the look out for an original sender unit and noticed that coolair sell both the reproduction unit and the VDO unit.
 

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Interesting for indeed. Surely if Heritage tell everyone they've had no returns (and then no-one returns the suspect senders) then they are technically right. However, you think they would have at least mentioned they've received calls about it.

With the back up knowledge you now have will they not offer a refund?
 

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Discussion Starter · #20 ·
Hey guys,

I've sent mine back for a refund, it's very interesting to hear you've had the identical problem joe, and that your readings are more or less identical to mine! Try emailing [email protected] and mention that you have had the same trouble as me. I'll keep you updated if my refund is successful!
 
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