I'm either getting bad mileage or I've got a problem with my fuel gauge or sender. I'm hoping that someone out there might have a 911 instrument panel in their 914 and have some insight. The 914 I purchased last year has a 911 instrument panel. The Fuel Gauge wasn't working due to a stuck sender, so I replaced the sender. I know that the tank is supposed to hold about 16 gallons, but my reserve light has been going on at about 240 miles. Do you think a 911 gauge and a 914 sender are compatable? If not, what do I do? Replacing my dash really isn't an option.

You know wrong. It holds closer to 11 gallons +-. IIRC.

You can actually see to the bottom of the tank with a flashlight (that might not be a good thing) so you can get an idea of what you have at 1/4 tank, 1/2 tank etc...

I've always heard 16.4 gals.

Correct, but...

If you put that much in, you'll get slosh and smell. At least in mine.

Yes

Essentially 0-90 ohms -- standard Bosch range. You can pull the sender and measure ohms to see if it's working fully.
Gauge can be tested with diodes.

When you top off your tank, reset your trip odometer to 0. When it reads 300 miles traveled, you might want to start looking for a gas station.

Pull the sender out of the tank and let it drain so the float will fall to the bottom of the tube. Then note what the fuel gauge indicates, which should be EMPTY.

Next, turn the sender upside down so the float falls towards the top of the inverted sender. Again, note what the gauge indicates, which should be FULL.

If not, the gauge may need to be repaired.

Where is the needle on the gauge when the light comes on? 911 and 914 use the same sender.

I've always heard not trust the gauge but always trust the reserve light! However, removing the sender and checking it is certainly an inexpensive and easy way to check the circuitry. You could also easily disassemble the sender to check the float and the readings with a VOM. I wonder if the resistance wires might get a coating from sitting in gasoline that interferes with accurate readings?

In my 914 and 930, when the fuel gauge goes below 1/2 tank, I refuel. For my road car, when the gauge gets to 1/4 tank, I refuel.

I don't understand the advantage of waiting til the reserve light comes on to refuel.

as Dad used to say, "It doesn't cost a damned penny more to keep the tank full than empty".

The tank holds approx 16.4. US gallons. Not 11! If your only getting 240 miles from a tank full, you have a serious fuel consumption problem. I'd bet the 911 gauge and 914 sender are just not compatible.

Again ... testing the sender and gauge will tell you a lot about the accuracy of that circuit.

There are a few other methods of testing the accuracy. One, that would consume more of your time would be to completely drain the tank. Obviously, the gauge should read EMPTY.

Have someone sit in the car to watch the gauge. Then start filling the tank in one gallon increments and note the gauge location and when the reserve light ceases to illuminate. There's your amount of reserve capacity in gallons.

Next, drive a short distance to the gas station and fill your tank. Take note of how many gallons it takes, and what the gauge indicates.

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Another method ... When the low fuel light illuminates, immediately pull into a gas station and fill your tank. Take note of how many gallons it takes. Subtract that amount from 16 gallons (or 16.4 if you fill to the very top). The answer is the amount of reserve capacity.

While performing either of these on-road tests, you might want to carry a 2 or 3-gallon gas tank in the trunk just in case.

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Also, as for fuel consumption, here are a lot of other variables that can affect your mileage. What are the specifications of your car?

Displacement

Induction system

Tire size (and tire pressure)

Alignment (heavy negative camber etc.)

Where the hell is the reserve fuel light

I have run the tank dry twice and never saw any light on .

Just above the empt/reserve line.

I agree. I'm just trying to understand the reliability of the gauges of this new purchase, along with determining my mpg.

Good input. I'll give that a try along with pulling the sender and checking it.

I concur, 16 gallons is right. Filled mine up today before heading to Garold's. Took 12.5 gallons when the gauge read a little above 1/4.

I have also been having gauge/sender issues though; Mine gets down to just under 1/4 and stays there. I learned a valuable (and embarrassing) lesson-when the light comes on, no matter what the gauge shows, head for the gas station NOW.
As for why yours may not be working, the reserve light is a completely separate circuit. I took a sender apart and there are a set of contacts at the very bottom that 'short' when the float drops all the way (near empty). One sender had crud on the contacts so the it never completed the circuit.

To test the light, pull the sender connector and short the W socket to the ground socket (3 lines above a T). If the light doesn't come on, you may have a burned out bulb.

The lamp may be burned out, or the wire to it may be faulty/disconnected

Even with spirited driving I easily do well over 300 miles, if I behave and drive for fuel economy I know I can get close to 400. 2056 with L jet

Ian Stott
Moncton
Canada