IM Experience bade Fuel Gauge Advise..?

To quote the Intermeccanica owner's manual:

"Fuel gauge stays "full" for a long time and falls fast. It reflects the shape of the tank. ...Do not take chances until you are familiar with the gauge".

OK, Fine, but what exactly does this mean?

I've bought one of their cars used, received it Sunday last. The fuel gauge reads full, or "4/4". I have approximately one inch of fuel in the 10 gallon tank. I'm not sure how much that amounts to but shouldn't I expect the gauge to have moved by now?

My first assumption was that the gauge was shorted or otherwise not working correctly and there are several threads which mention a gauge that reads full all the time.

To be honest I had missed the instruction above when going through the manuaal - my wife pointed it out to me after I had pulled the sender and ohm'ed it, switched wires around on the gauge and put them back and was about to conclude that the gauge was defective.

So is there an experienced Intermeccanica owner who can shed some light on this characteristic for me? How much warning will the gauge give before the car runs out of gas?

My first call abbout this would be to Henry at IM. He is the expert on his cars and has the answers. Click on "Makers" at the top of this page and find his telephone number.

Second option may be to ask your wife--hehe.

I've pestered Henry quite a bit (and he's been uniformly great!) and know that he's especially busy this week preparing for their IM Wine Country Tour this coming weekend, so came here instead.

Consult my wife? Yeah! I could send her out with the car to go for a long ride with the full tank and wait until she runs out of gas. She'd be sure to tell me exactly what the gauge did......uh, huh, as she slowly slit my ........shirt. Besides, I'd miss dinner. :D

(I didn't type "bade" I don't think...?)

The focking thing is broken...

Fuel gauge reading on my Vintage is equally inaccurate.

Take today for instance....

Picked up the car from Kauth & Mayeur today after some problems with the dual 40 Dellorto's. One of them had a problem with the needle and seat, and was expertly fixed by Michael Benet. He test drove it, declared it right and I came to get it.

Looked at the fuel gauge pegged at 4/4, thought it was odd since when the driver side carb went squirrely on Monday it sucked up at least 1/4 of a tank in the span of 12 miles, dripped gas all over the place, and filled the crank case with petrol as well. The mother of all flooding incidents.

Idiot Boy (me) believed what I saw on the gauge and headed onto the 74 freeway on ramp which narrows rapidly to two lanes one way as it becomes the bridge over the Illinois River.

Engine sputters, feels like it is bogging and quits as I am literally merging into the outside lane. Nowhere to go, traffic is backing up, trucks are blasting by so close that I had to move my substantial butt across to the passenger side and bail out. Horns honking, middle fingers being elevated from closed fists, screeching brakes, and I've got no place to go but hard against the railing and faced with a 40' drop if I have to go over the side. Of course, no flashers or emergency lights and I threw the flares and emergency kit into my wife's Benz last week.

Grabbed the trusty cell, notified Illinois' finest that I had become a hazard, called for a tow and thought it must be the carbs again.

Tow showed quickly, took the car back to the shop and determined that the gauge couldn't have been displaying more bogus information than 4/4!

Tomorrow the fuel filter gets replaced, the lines blown out, the gauge and the actual unit in the tank checked/fixed/replaced, and I'm thinkin' the gas tank gets topped off.

Lovely afternoon.

Yeah, your gauge should show a change before it gets that low.

If it's a standard style gauge, if you pull the sender wire off, it should read empty. If you ground the wire it should read full. If the gauge works doing this, then most likely the sender's grounding on the tank or just plain bad. If it doesn't, pull the wire at the back of the gauge to eliminate a short in the wire.

It has a German made VDO sender with a VDO gauge in a combination. The sender measures 5 ohms to about 75 ohms. Someone in this site said that VDO senders are normally 10-180 ohms. With the sender out of the tank and connected it does not cause any movement of the gauge with a full swing from one limit to the other. The gauge itself seros with key off (slightly below the 'r' mark and goes to exactly the full (4/4) mark with key on, but not beyond full at all. It does this with the sender connected and with it disconnected - no difference.

The float is good. The grounding is good and the copper washer in place on the ground. I have 2. +/- volts on the hot connector at the sender, key on.

I'm not sure of the amount of fuel one inch deep represents. The tank is supposed to be 10 gallons but doesn't look it to me. It looks barely larger than a jerry can laid on it's side, and it wedges down from it's widest side. It's about 5" deep at it's widest so I'd guess 1" could be two gallons. I'd be OK with a gauge that dropped suddenly to nothing with one gallon left to run. Heck, I put almost 200K miles on my old '61 Camper that never had a fuel gauge - just a cable to open a flap in the tank releasing the 1 gallon reserve portion.

Check here: http://www.egauges.com/pdf/vdo/0-515-012-178.pdf

That says a VDO gauge should read full if the wire's disconnected. Opposite of what I saw in my service manual. You didn't mention what the gauge does if you ground the sender wire. If it shows empty when grounded, replace the sender.

Hard to say what Ohm range to expect without knowing what style sender or part number. But I assume it's a 10-180 Ohm swing arm style.

I've got the big (15 gallon?) tank in my IM. The needle stays pointed at 'full' for a long time, then slowly moves down to about the middle. From there it heads, at a much faster pace, towards empty. The drop from 1/4 to empty can happen at an alarming rate.

Although this IM described characteristic of reading full for many miles may well be the case, I do suspect the sender I have. It's marked VDO and Made in Germany on top but any part number must be shown to the inner tank. I'll make note of it next time I pull it out.

wouldn't the gauge read below half with a full tank if the sender range is 5 - 75 instead of the specified 10 -180 ohm range?

Either way unless my multimeter's gone south I didn't read anywhere near the 10 - 180 ohms listed for VDO leverarm senders. It measured closer to the 60-90 to 0 spec of VDO tube type senders, but isn't one of those.

I'd like to swap to a 15 gal. tank so maybe I'll order one now with a sender.

Who's best vendor, and do any ship free?

When I install the fuel float in a tank, I bend the float arm stop so that when the gauge reads 7/8 the float is actually in the full position, this allow for a little less than a gallon of "reserve" fuel in the tank from what is showing on the gauge.

"When I install the fuel float in a tank, I bend the float arm stop so that when the gauge reads 7/8 the float is actually in the full position, this allow for a little less than a gallon of "reserve" fuel in the tank from what is showing on the gauge."

Huh? How much is in the tank when the gauge reads 1/8?

If the tank was rectangular, 2/8ths. He does that so he has 1/8th left when the gauge reads empty.

Yes....

Take an ohm meter and read what the ohms are full and empty, you can take the float out of the tank to do this. It's easy to remove, then you can see what it's reading wherever you put it. You can also see what moving the float does to the guage. When I bought my older IM, it had a VW float and sending unit in it, I have original 356 guages in the car. They were not compatable. I measured the ohms to see what the guage required and then I picked up a universal float and sending unit with the right ohm range off of ebay for about $25. It's a pretty simple thing to do.

Mine has quit working again. It stays stuck at 3/4 now.

Vs has got probems with their gauges . the speedo don't count the miles good eather.. I want to go mechanical on the gas gauge. or send the things to North Hollywood instruments for total guts rebuilds.

1963 bugs were mechanical and gave good readings always the gauge will bounce some but it works.

I love the the dial overlays they look great at night .I'd want to keep that because how easy they are to see at night.

But the internal stuff is junk.

Dave,
I did ohm it and got the 5-75 ohm reading, empty to full, holding the sender in my hand as I said above: "The sender measures 5 ohms to about 75 ohms". I've ordered a new VDO sender because that reading doesn't jibe with the VDO website 10-180 ohm data on their swingarm senders. The gauge, thank goodness, does pass the VDO testing procedure. I wasn't looking forward to pulling the gauge housing because it's prety tight to the IM frame crossmember that runs just behind the dash.