Jessa

I just filled the tank, very nervous about how close to empty the gauge was. It only drank 14 gal, which is about right for the 210 miles on the trip odometer. According to the manual the tank's supposed to be over 20 - so why was the needle down at empty when there should be at least 6 or 8 more gallons left?

It didn't used to do this (at least not measurably); seems to have started after the car was driven for a couple of days with many of the instruments disconnected. Could that be the cause of my sagging needle? Its not that this is a big problem, but it sure does bug me.

Jay Wellwood

Jessa-

This seems to be an area of debate and contempt for the 928. There is a great deal of past discussion (or cussin') of the 928 Fuel Gauge and its' accuracy (or lack thereof).

From what I understand...apparently this 'drifing' of the fuel tank level sensor is expected after some period of time.

hth-

John Struthers

Jessa,
Pattycakes, a sister to your sHARk has the same "sagging problem". She will, however, be 20 years old next month. I have asked the Board in general how old that is in 'DOG' years but no one seems to know...
In any case, the fuel gauge has always been inaccurate but never critically so. Mine always reads low at fill-up - there have been a multitude of posts on the board, check archives, and a mention of the issue on the Greg Nichols site. Your owners manual should give you an idea of how many liters remain when you hit 'RESERVE'.
"RESERVE on the otherhand is a bit of a mystery... ... does reserve start when the needle hits the orange/red line, or, when the low fuel warning light comes on? Frankly, I dunno.
I have found that the fuel pump makes itself known - it gets loud and starts 'thumping'- when you are at a low fuel state. Particularly, at idle. If you feel adventurous YOU can see how many miles you can get on empty.
I don't believe the Wiessach gauges are any different than those of other sharks in general and the 82's, 82' S, and Weissach in particular.
I'd be willing to bet that on occasion the magic
Mile Per Gallon gauge and the Oil Pressure gauge make a mockery of accuracy as well. If you had the time and a good bit of $$$ to throw at the problem the 'problem' could be calibrated out. However, in the real world these problems don't generally justify the cash expenditure to fix them. On the other hand, if you have the bucks to resolve these gauge problems, perhaps I could interest you in donating a dumptruck load of cash too a worthy charity in need.
BTSOOW -Battered Texas Sharks Out Of Water- Just send the Loot... er... donations to my home address and I will personally see that the funds are disbursed amongst my fellow Texas Shark Wranglers, except for those using them as Farm machinery or hunting vehicles. Those plows and and brush guards just don't look OEM.
Keep em' Rolling.
Later,
John S. 82' Weissach, Auto. 'Pattycakes'
<img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

Jeremy B

I'm now have an 84 928 S my second 928 and both cars have exactly the same problem with the fuel gauge i just live with it and know that when it gets really low I just fill it up.

Jeremy <img src="graemlins/xyxwave.gif" border="0" alt="[bigbye]" />

Kevin in Atlanta

There was also talk of a resistor on the back of the instrument cluster (100r/5w?) that could cause lower readings.

Sab

I have exactly the same problem. If I fill up completely the gauge reads 3/4. After about 200 miles it shows empty and only takes about 14 gallons. I typically wait for the warning light to come on and can then fit about twenty gallons. I beleive my manual states 24 gallons capacity.
I would really like to get it resolved since my odometer gear just recently broke. So I am relying entirely on the warning light.
Let me know if you fix it.
cheers,
Sab. <img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

Curt

FOR EVERYONE ABOVE: When you fill up does your needle go all the way up to the full mark?? If not you probably are having the same problem I had when I first purchased my car. The fuel guage was accurate. The tank just wasnt filling up all the way because the vent hose was crimped close. Our tanks are shaped very odd. As you start to fill the tank the fuel exits the pump and goes down into your filler neck, the neck enters the tank just above the middle of the tank. When the fuel level reaches that point as your filling, air needs to escape out of the tank so it exits via the vent hose which is attached at the top of the fuel tank and routes itself down along the fuel tank and back into the filler neck. In my case the PO had the tank off and when he installed it back up he crimped the hose between the tank and body of the car cutting off the venting capability. so when I was filling up the beast it would only allow just over half a tank to be put in. My guage always read correctly. So I dropped the tank and reran a vent hose. Slapped it back together and what do you know, I can fill it all the way up and the guage pegs the top. Yippeee for me.

Hope that makes sense, im too tired to recheck my typing so sorry for any mistakes.

John Struthers

Thanks, Curt.
Maybe you fixed two Weissach's for the price of one , or, was that, two Weissach's with one stone.
I've read that tip before but it is usually associated with a gas smell in the car as well.
I'll give her a gander.
John S. <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />

Sab

I drove about 80 miles on the warning light the other day and got 22 gallons in the tank, so I don't think I have any crimped hoses. Either my gauge is bad or it's the sending unit.
My voltage gauge reads low as well, I had it tested the other day and the alternator checked out fine.
regards,
Sab.

Jessa

Looking from benieth the car, I can see a very small portion of hose. What's the best way to get a good look at the rest of it to check for kinks or crimping?


John, from what I understand of "dog years", our cars about 140. And at that age, I'm afraid all my charitable contributions must go to BCSOOW.

Rob from NH 87 S4

Just weighing in...

My 87 S4 when full never quite makes it into the top 1/8th of the full gauge.

I seem to only take about 14 gallons.. perhaps the tip about the vent hose in the tank is something I should consider.

If it's not one thing, it's two things, and sometimes three things.

<img src="graemlins/c.gif" border="0" alt="[ouch]" />

V-Fib

My gauge, like Rob's reaches within 1/8 in. and only takes 14 gals. But then, filling up is kinda fun with all the "Nice Car" and other favorable comments you get at every fill up. May I dare say, I don't believe fuel economy has ever been the title for a post here for 928's.

Anthony Tate
79/928 Silver Metallic

Jerry 87 928S4

Not only do I not like the fact that my guage does not quite read full but I really dont like the direction of the guage. I wish it was horizontal instead of vertical - wow - only this board would have ever made me think of that.

Dan Bise

It sounds like a lot of folks with this problem would be able to put in the full 22-23 gallons if they risked waiting until the low level warning light lit. What Sab said is right on. It'd be worth it to putter around near the house carrying a 2 gallon gas can in the car just to run the car dry, as an experiment. It's gotta drive ya nuts to have to live with this problem, no?

I had the fill problem that is related to the vent hose, which only allowed me to put in 11 gallons. More could be forced in, but very slowly via little squirts. Other reports I've read in the past also reported the ability to go only "half full." 14 gallons sounds like venting is not the problem.

As to checking the kinked hose, you'd have to lower the tank. The act of dropping the tank will extend the hose so much that it will not appear kinked at all. I had a very strong suspicion mine was kinked, but the hose appeared to be in great shape after I removed the tank from the car. I didn't even bother to replace it the hose - I just replaced the tank very carefully, making absolutely sure the hose didn't bind on the way up. Sure enough, I was able to fill up all the way afterwards.

Also as to "reserve", the amount of fuel you have left after your low fuel light comes on, I compared notes recently with my SOCAL928 mates after a long drive from L.A. to Phoenix for a PCA event. My light comes on at 2 gallons remaining (same as the owner's manual). Others reported 3 gallons.

Dan
Pasadena, CA
'83S

V-Fib

I don't think I would "run it dry" without hearing what Wally P. and some of the others "Guru's" think about it. I have had a couple of other vehicles that running the fuel pump dry even once, caused them to fail prematurely. But then again, I may be wrong.

Anthony Tate
79/928 Silver Metallic