| Author |
Message |
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
 Posted: Mon Mar 19, 2018 5:19 pm Post subject: Gas Gauge Is Messing With Me |
 |
|
Ordinarily, I don’t fill the tank in my ‘74 Super Beetle, because I don’t put that many miles on it, because, as we all know, gas goes stale.
Today, however, I filled the tank. The gauge read a bit less than 3/4 full. Take into account that it previously would read 7/8 full when full. So, I’ve lost an additional ... little more a 1/8 reading on the gauge.
About four years ago, I replaced the gauge, vibrator, and sender (the sender was an expensive VDO from Wolfsburg West), and the gauge read almost full—just a hair from the 1/1 mark. Then, a few months later, on a trip to Bugorama in Sacramento, I stopped at a Shell station and filled up. The gauge immediately went only to 7/8 full. Okay, I could live with that, but now on a full tank, I’ve lost more reading.
Anyone else have this happen? I’m pretty sure it’s not the sender with the half-reading-burnt-out-rheostat problem because the gauge is almost at the 3/4 mark when full. So, I’m wondering if anyone else has had this sort of gradual degradation of the reading on their gauge, and if it was the gauge giving up, or what?
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
 |
bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
|
| Posted: Mon Mar 19, 2018 6:15 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
note sure what is going on with the gauge. But you should consider that a partially full tank tends to breath more with temperature changes, and thks can lead to more water ingress from humidity and thus cause more rust. Usually it is recommended to store a car with a full tank, but as you say, the gas can gl stale, perhaps with use of Stabil gasoline stabilizer can help keep the fuel fresh. I have used Stabil and the gasoline a year later still seemed to work just fine.
Consider storing with Stabil and a full tank.
For the gauge, consider that maybe the float has gained weight and sinks lower now. that can happen.
you may wish to remove the float assembly and sweep it by hand to see if your gauge will indicate full when float is moved to extreme top end or not. if it does read full, then consider that the float may have absorbed fuel, flooded.
also consider the specific gravity of the gasoline may change. seasonal variations in the gasoline addition of alcohol, can alter the specific gravity. regular gasoline per the interweb search can be between .71 to .77 and E85 fuel can be .8. this variation might account for a small change in the gauge reading, equal to about 1/8 th the hieght of the float, which is probably a very small amount on the gauge considering the float probably moves up and down near ten inches or so, so that likely on a few percent difference in max reading, much less than what you are seeing
For my 61 Bug, it never had a gauge, that was not offered as standard equipment until 62 for
US market Bugs, so I simply mark the odometer reading at a fill up, top it off every time and know that around 200 miles elapsed is time to fill her up again.
But with a stabilizer, your gasoline should be ok for some time, and a topped off tank does breath less, so less water problems.
To test the float, submerge it in a pot of hot water on the stove and see if it bubbles or not, if it bubbles it has leaked or absorbed fuel.
You could also weigh the float, but you'd need need to know what the weight should be or was prior to the problem to make that info useful.
BUG ON! Now fill that tank!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Mon Mar 19, 2018 6:54 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Thanks, Blue. I paid $115.00 for that VDO sender and was hoping there wasn’t an issue with it. There are two floats on the Super Beetle senders, and I’m suspecting that one of them—or the arms—is not up to snuff.
When I first got the sender, I tested it and got 10-70 while moving the arms. That was perfect. But the issue seems to have started the moment after I put Shell gasoline in the tank. Coincidence? Maybe.
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien
Last edited by Tim Donahoe on Mon Mar 19, 2018 10:01 pm; edited 1 time in total |
|
| Back to top |
|
|
cletus_zuber
Samba Member
Joined: January 08, 2010
Posts: 2408
Location: Gladstone, Ore
|
| Posted: Mon Mar 19, 2018 7:12 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Never trust any Dutch gas.
_________________
1972 1302
HPMX 40's & 019 |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Mon Mar 19, 2018 11:56 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
I just remembered, with ignition on, if you take the sender wire off the sender connection and ground it--and the gauge goes to full (1/1), then the gauge is not my problem.
Here's to hoping the gauge doesn't move to full when I get the wife to help me with the test this Saturday (unless I can get her to help sooner).
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
|
Busdriver79
Samba Member
Joined: July 22, 2011
Posts: 1655
Location: The Peoples' Republic of "No" Jersey
|
| Posted: Tue Mar 20, 2018 6:46 am Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| Why do VWs have so many fuel level issues?...VWs have a crappy and unreliable fuel gauge system...my 73 Super Beetle has two floats...what's up with that?...and that gizmo behind the speedo is a PITA to get at and change again...I'm tired of always having to fix this...are there any suitable substitutions for the VW system?...originality is not an issue. |
|
| Back to top |
|
|
Dwayne1m
Samba Member
Joined: December 31, 2011
Posts: 3538
Location: Pennsylvania
|
| Posted: Tue Mar 20, 2018 2:26 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| Busdriver79 wrote: |
| Why do VWs have so many fuel level issues?...VWs have a crappy and unreliable fuel gauge system...my 73 Super Beetle has two floats...what's up with that?...and that gizmo behind the speedo is a PITA to get at and change again...I'm tired of always having to fix this...are there any suitable substitutions for the VW system?...originality is not an issue. |
Yep. Fill up, record mileage, go 200 miles. Repeat.  I'd like to have a reliable fuel gauge but it seems like even the "reliable" ones aren't reliable, so I have learned to trust & use the odometer. Maybe someday when I have nothing else on my project list (like that will ever happen) I'll look into spending time trying to improve the fuel gauge situation, but for now it isn't even near the top of my priority list. |
|
| Back to top |
|
|
BUGGED11111
Samba Member
Joined: February 03, 2006
Posts: 1821
Location: Oregon
|
| Posted: Tue Mar 20, 2018 3:42 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Possible that since you don't fill up that it caused the rheostat to get some dirt/oxidation on it from lack of use. I would try cleaning it up with some contact cleaner that also removes oxidation. Worth a try. Ya' never know with these things
Last edited by BUGGED11111 on Tue Mar 20, 2018 3:44 pm; edited 1 time in total |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Tue Mar 20, 2018 3:44 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Bugged, that’s a good idea. I’ll have to give it a shot after the gauge test.
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
|
BUGGED11111
Samba Member
Joined: February 03, 2006
Posts: 1821
Location: Oregon
|
| Posted: Tue Mar 20, 2018 3:45 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| I've had that happen even though I do fill up so yup worth a shot |
|
| Back to top |
|
|
VW_Jimbo 
Samba Member
Joined: May 22, 2016
Posts: 9967
Location: Huntington Beach, CA
|
| Posted: Tue Mar 20, 2018 6:32 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| BUGGED11111 wrote: |
| Possible that since you don't fill up that it caused the rheostat to get some dirt/oxidation on it from lack of use. I would try cleaning it up with some contact cleaner that also removes oxidation. Worth a try. Ya' never know with these things |
When you are driving around town or down the road, the gasoline in the tank is not static. It continuously sloshes here and there. Up one side and down the other side. That gasoline is fluid and thus, it moves around - ALOT.
Fill a Tupperware container up with water, tape it down to the body somewhere, and go for a drive. That stuff MOVES!
So, why I am saying this. The rheostat within the tank is getting a work out. Highly doubt it has carbon tracks upon it, although that may be possible, I would think that the motion of the arm being thrust up and down would wipe that clean. Add being soaked with gasoline or having it splashed up onto it. Just my opinion, I have nothing to back it up.
The other portion of the system, the vibrator, should be questioned and tested. Also, the ground path to the tank needs to be checked.
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
GFY's Xevin and VW_Jimbo!  |
|
|
| Back to top |
|
|
VW_Jimbo
Samba Member
Joined: May 22, 2016
Posts: 9967
Location: Huntington Beach, CA
|
| Posted: Tue Mar 20, 2018 6:40 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| Tim Donahoe wrote: |
I just remembered, with ignition on, if you take the sender wire off the sender connection and ground it--and the gauge goes to full (1/1), then the gauge is not my problem.
Here's to hoping the gauge doesn't move to full when I get the wife to help me with the test this Saturday (unless I can get her to help sooner).
Tim |
That is the correct test for killing the gauge and the vibrator. The correct test for testing the system is reading the Ohms being controlled by the sending unit, or reading the voltage to the gauge and comparing to known good values.
I have seen several hundred gauges that were bad, due to the exact test you refer to. After that car came in to me. I would replace the gauge and the vibrator. Gauge would almost always work then. Once in a blue moon, the rheostat on the sender was bad and had shorted out, killing the gauge and vibrator.
Then there was my current 70, that burned through three sending units before I figured out the ground path through the tank clamps and bolts was bad. All that potential killed the rheostat. Ended up running a dedicated ground to one of the screws at the sending unit. That was the temporary fix and proved my solution. I ended up removing the four bolts and steel clamps, brushing them down to bare steel and then smearing on dielectric grease. That was the cure! Now the tank has a great ground path; and I no longer have to but sending units; and my gas gauge works!
However, there is a whole other story of how I had to bend the arms to get the gauge to read correctly. But that is a different story.
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
| GFY's Xevin and VW_Jimbo! |
|
|
| Back to top |
|
|
bnam
Samba Member
Joined: July 02, 2006
Posts: 2936
Location: El Dorado Hills CA/ Bangalore, India
|
| Posted: Tue Mar 20, 2018 7:25 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Tim,
I've experienced the same on my original vdo set up in my 71. I cleaned the rheostat and took measurements. I finally found increased resistance at the tip of the rheostat wiper. The wiper arm has a nub attached to it (crimped IIRC) and I measured resistance in that connection. So, I added a blob of solder - not well I must admit - but well enough that it decreased the resistance and the needle which had dropped to almost 2/3rd tank at full is up to 7/8ths now. with the arms fully up I measured 11.xx ohms. A bit more than it should be. IIRC, 10ohms is the correct full reading (or I misremember as it has been a while).
Let me see if I have any pics of what I did.
Byas
_________________
1971 1302LS Convertible (RHD) owned since '74
Click to view image
1965 Karmann Ghia Coupe - under restoration
1966 Fiat 1500 Cabrio (with 1600 Twin cam)
1952 Citroen TA 11BL |
|
| Back to top |
|
|
bnam
Samba Member
Joined: July 02, 2006
Posts: 2936
Location: El Dorado Hills CA/ Bangalore, India
|
| Posted: Tue Mar 20, 2018 9:26 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Measuring resistance from tip of wiper to axle pin.
Solder blob to aid connectivity
End result - not quite full tank but much better.
Rheostat was also cleaned.
_________________
1971 1302LS Convertible (RHD) owned since '74
Click to view image
1965 Karmann Ghia Coupe - under restoration
1966 Fiat 1500 Cabrio (with 1600 Twin cam)
1952 Citroen TA 11BL |
|
| Back to top |
|
|
Tim Donahoe
Samba Member
Joined: December 08, 2012
Posts: 11740
Location: Redding, CA
|
| Posted: Tue Mar 20, 2018 11:15 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Jumbo, Speedy Jim and Bentley suggested grounding the sender connection, so it seemed plausible. With a properly-functioning vibrator, I don’t see how the gauge would be damaged. But, you should know, so I may skip that testing method.
Tim
_________________
Let's do the Time Warp again!
Richard O'Brien |
|
| Back to top |
|
|
VW_Jimbo
Samba Member
Joined: May 22, 2016
Posts: 9967
Location: Huntington Beach, CA
|
| Posted: Wed Mar 21, 2018 7:40 am Post subject: Re: Gas Gauge Is Messing With Me |
|
|
| Tim Donahoe wrote: |
Jumbo, Speedy Jim and Bentley suggested grounding the sender connection, so it seemed plausible. With a properly-functioning vibrator, I don’t see how the gauge would be damaged. But, you should know, so I may skip that testing method.
Tim |
It’s with anything out of spec. That item is unknown and may cause damage to whatever is attached - even testing equipment. I had a cheap DVOM when I started as a mechanic. It came with an amp reading function but was not internally protected. Hooked it up to a headlight circuit, and let the smoke out of the meter. Spec stated that the 15amp fuse should have been blown first, but it did not. Instead the lamp had shorted to ground on the high beam circuit, so when I hit the switch, the amps went through the roof. I saw the smoke!
So, my point is. Even with all the written knowledge out there readily available , there are things that even the best engineer would never think could happen. I am hear to tell you that they do and often. Testing a failing circuit is one of those things. If something is marginal, the test my put it over the top. Whatever the top is, you will be the recipient.
Think back to the Pinto gas tank. Or the Escort air bags, or .....
Just finished running a new laundry room 220V circuit through a house due to a non running dryer. It would spin but no heater. Customer bought a new dryer, because the guys voltage tester said the circuit was good. Two days later, they need another dryer. The manufacturer sends out their guy, who reports back all is well. Well long to short two more dryers and then a call to me. I solve difficult problems. I find a nail through the neutral wire in the laundry room in back of a wall cabinet. Nail heats up due to a short going on between the two legs of 110. Gets hot and the nail expands and then shorts the two together, making for 220 volts at the dryer, for a split second, then it disappears! Took me two hours to get it, but when I did the regular tests would not have worked, they would have shown a normal voltage.
_________________
Jimbo
There is never enough time to do it right the first time, but all the time necessary the second time!
| TDCTDI wrote: |
| Basically, a whole bunch of fuckery to achieve a look. |
| 67rustavenger wrote: |
| GFY's Xevin and VW_Jimbo! |
|
|
| Back to top |
|
|
bluebus86
Banned
Joined: September 02, 2010
Posts: 11075
|
| Posted: Wed Mar 21, 2018 7:57 am Post subject: Re: Gas Gauge Is Messing With Me |
|
|
reminds me of an industrial furnace controller computer. new install, computer would lose it mind. weeks of experts analyzing the power waveform, fancy scopes, etc.... one day while they are talking around an open panel, I stop to listen to what is going on, I look at the open panel and see some thing a contactor, and then I say to them, hey, you got a white wire and a black wire two each, the white wire enters the top of the contactor on the left, exits at bottom on the right, and black wire just the opposite.
they electricians, the experts hear that and say, oh god! someone had swapped the hot and neutral wires at the contactor. they swapped one of the white for black wires and bingo, the computer ran fine after that.
leason... sometimes its the simple stuff.
my dad had new siding put on his house, after that the phones had static. he supposed a nail went thru the phone wire. the siding guy said no way could that happen. so dad put a signal thru the wire and went around with his rf meter till the signal changed. he marked the spot and asked the siding guy to open up the siding at the mark. sure enough, nail thru the phone wire!
Bug On!
_________________
Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
|
| Back to top |
|
|
Cusser
Samba Member
Joined: October 02, 2006
Posts: 31379
Location: Hot Arizona
|
| Posted: Wed Mar 21, 2018 9:03 am Post subject: Re: Gas Gauge Is Messing With Me |
|
|
I bought a brand-new townhouse in 1979. A week or two later, was trying to cook something in the oven broiler, forgot about it, but it wasn't all burned up. Called builder, they sent out oven repairman; turns out that the oven was only hooked up to 110 VAC, so builder had to rewire.
My place up north: even with home inspection, turned out that hot and cold to the washing machine were switched, inspector missed that. So I swapped the valve handles to color-code them correctly.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
|
| Back to top |
|
|
Blue69Baja
Samba Member
Joined: September 04, 2008
Posts: 1065
Location: Fair Oaks
|
| Posted: Fri Mar 26, 2021 3:19 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
Delete post.
_________________
69 Baja with a 1914...
72 Super 100% orig...W/ factory air... 56,000mi
Even the spare is original..
Last edited by Blue69Baja on Fri Mar 26, 2021 5:19 pm; edited 1 time in total |
|
| Back to top |
|
|
goober
Samba Member
Joined: May 03, 2003
Posts: 1183
|
| Posted: Fri Mar 26, 2021 4:57 pm Post subject: Re: Gas Gauge Is Messing With Me |
|
|
I don't understand all the gas gauge problems. Maybe it's because my '69-'70 Bugs have a simpler screw-down sender and tank?
I can't remember the last time I replaced a sender, vibrator or gauge. They just keep working normally.
Maybe try taking out your sender and see if the float is moving/wiggling around improperly? |
|
| Back to top |
|
|
|
