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Xevin Samba Member
Joined: January 08, 2014 Posts: 7623
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Posted: Fri Sep 17, 2021 7:24 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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blue72beetle wrote: |
Is that a battery door? |
PITApan style 😉😂 _________________ Keep on Busin'
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
Clatter wrote: |
Damn that Xevin... |
skills@eurocarsplus wrote: |
I respect Xevin and he's a turd |
SGKent wrote: |
My God! Xevin and I 100% agree |
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Jetfxr69 Samba Member
Joined: December 28, 2018 Posts: 1293 Location: White mtns nh
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Posted: Fri Sep 17, 2021 7:52 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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I was thoroughly confused about your last pic…until I noticed your sig line. I have nothing to offer then best wishes for a speedy repair. _________________ You can't be a real country unless you have a beer and an airline. It helps if you have some kind of a football team, or some nuclear weapons, but at the very least you need a beer. Zappa
‘77 westy Seamus
‘76 tintop Crusher
‘77 westy The Judge
‘72 tintop bastard westy Hudson |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Fri Sep 17, 2021 7:54 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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1978 uses an optional electronic voltage regulator to regulate supply voltage, or standard buzzer style voltage regulator (that turns voltage on and off) to lower voltage (or duration with the buzzer style) at the dash gas gauge. The dash gas gauge is a bimetalic strip that is heated by the electricity flowing, and as it heats the needle moves towards full. The warmer the higher it reads. The amount of positive voltage (or duration) to it is constant and comes thru the dash voltage regulator, and the ground which controls the amount of heat is variable at the tank sender. The lower the resistance at the tank sender the more current flows so the more the gauge heats up - hence the higher it reads.
At lower ohms (say 13 ohms when full) more current is flowing to heat the needle. At higher ohms (say 83 ohms when empty) less current flows so the needle heats up less and reads lower.
It is hard to envision a situation that would fully read in reverse. The only thing I can think is a worn spot in the sender up near full so it acts as an open circuit, and the needle cools off. Then when low, there would have to be some kind of a situation where the float hangs up and reads near full when the tank is actually lower. I have seen senders sit on a certain level for hours then a pothole in the road jars them where they drop to the correct level and suddenly the gas level falls, while the driver panics where on a 100 mile stretch they will get gas. Good luck.
The image below is from Richard Atwell's site.
_________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sat Sep 18, 2021 7:20 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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I believe I posted yesterday that I had started to figure my problem with the engine having a miss was from bad fuel and filling up with fresh took care of that. It ran great for several hours.
But that miss came back later in the afternoon. At some point, I thought maybe the actual problem was the tank vent wasn't venting and I was drawing a vacuum. So at one point when it was missing, I stopped and opened the filler cap, hoping to hear a whoosh. Nope. And we carried on down the road, still with the miss that felt like fuel starvation.
I found an AutoZone on the map, and was delighted that they had a filter! I quickly got to work, thankful that I brought my tools to pinch fluid lines closed.
But they didn't actually work that well! Which I discovered when I got the filter disconnected. The main evidence was a flood of diesel flowing into me.
Worst part was the filter they had, was actually slightly different! Enough to be unusable.
So I got the bright idea of getting a couple in line filters instead. That took a couple trips into the store, dropping diesel out of my hair, to accomplish. But I got it together.
Katherine got me a change of clothes and I cleaned up a best I could in their bathroom, just throwing the soaked clothes away and headed to the next truck stop with a shower.
I feel nervous saying the filters fixed the problem, but after the shower and the rest of the way to our destination, it ran fine. I did drive just a little slower in an effort to reduce fuel demand a bit.
We arrived a few minutes after midnight Eastern (losing an hour shortly before getting there), hastily set up the bus, and had a couple beers. I'm not sure if we'll ride with Katherine's cousin to the wedding, or drive the bus. I think I hope we ride together.
The cousin lives on top of a hill way out in the boonies. It's pretty nice here, but there is really only one flat spot.
_________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sat Sep 18, 2021 8:47 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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SGKent wrote: |
1978 uses an optional electronic voltage regulator to regulate supply voltage...
...I have seen senders sit on a certain level for hours then a pothole in the road jars them where they drop to the correct level and suddenly the gas level falls, while the driver panics where on a 100 mile stretch they will get gas. Good luck.
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This is what i originally thought was happening when I first noted the needle was in the red on the gauge and went and filled up.
But since that time, over several fill ups, I've been able to observe that the needle slowly rises as we're driving. And by that I mean, at a rate very similar to how it used to slowly fall as we're driving and fuel is consumed.
And it is very consistent. I've been stopping to fill when the needle has gotten to about halfway into the red, and it always takes about 9 gallons. I'm not sure where the needle would be at empty. I do have a couple gallons in a fuel can, but I'm nervous to push it because it's a pain to prime a diesel engine if you run out of fuel.
Would it read reverse if the positive and negative wires on the back of the gauge were switched? I haven't touched them in a long time, but this is acting so weird I almost wonder if someone did something to mess with me! _________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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Xevin Samba Member
Joined: January 08, 2014 Posts: 7623
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Posted: Sat Sep 18, 2021 8:59 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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vwwestyman wrote: |
I almost wonder if someone did something to mess with me! |
Was stuartzickfoose in Kansas recently _________________ Keep on Busin'
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
Clatter wrote: |
Damn that Xevin... |
skills@eurocarsplus wrote: |
I respect Xevin and he's a turd |
SGKent wrote: |
My God! Xevin and I 100% agree |
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mikewire Samba Member
Joined: March 22, 2010 Posts: 805 Location: San Antonio, TX
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sat Sep 18, 2021 9:08 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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Xevin wrote: |
vwwestyman wrote: |
I almost wonder if someone did something to mess with me! |
Was stuartzickfoose in Kansas recently |
Aha! He was actually relatively (relative to the overall continent) close to us labor day weekend so we discussed getting together, but they were actually still 5 hours away so it didn't work out. _________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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SGKent Samba Member
Joined: October 30, 2007 Posts: 41031 Location: Citrus Heights CA (Near Sacramento)
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Posted: Sat Sep 18, 2021 10:19 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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if you have a stock bay sender for your year, you could not hook it up backwards. If you have the standard buzzer style gauge VR then it could mean that the voltage in the bus is climbing. If it is the black plastic housed electronic VR it regulates the dash gauge voltage using a zener diode. Either way I would check the battery voltage with it running to make sure the main VR isn't going bad and pushing voltage up to 16v etc.. Also check the engine and frame grounds to be sure they aren't loose or corroded. _________________ “Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin |
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Xevin Samba Member
Joined: January 08, 2014 Posts: 7623
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Posted: Sat Sep 18, 2021 11:06 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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SGKent wrote: |
Also check the engine and frame grounds to be sure they aren't loose or corroded. |
^^^This easy to do, can never hurt to clean them up. I usually start there first with an electrical gremlin. Easy to eliminate this issue from the puzzle and then dive into to other possibilities. It worked for me twice in the Bay, once in the bug, and once in the Vanagon. You have a swapped engine I know nothing about. _________________ Keep on Busin'
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
Clatter wrote: |
Damn that Xevin... |
skills@eurocarsplus wrote: |
I respect Xevin and he's a turd |
SGKent wrote: |
My God! Xevin and I 100% agree |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sat Sep 18, 2021 12:02 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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mikewire wrote: |
I recently replaced my fuel sender, and after a few drives the gauge went to R. I opened up my access hatch and pulled the sender...the float was MIA.
I did find it, hiding out in the corner of the tank.
So, I'm not sure if you are dealing with something similar, but watch out for a migrating float! |
Thought about this. But can't figure out how that could cause the gauge to rise as fuel is consumed. _________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Posted: Sun Sep 19, 2021 8:46 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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Well the wedding went off with only one hitch. Silas had a ton of fun running around everywhere with his baby walker and figured out how to climb stairs.
We left Katherine's cousin's place this morning. Bus kept having an intermittent issue of losing significant power then having it come back. This time, I was getting a code for the mass air flow sensor. I saw that one time after the AutoZone mishap. But today it was awful driving that way.
Eventually, I pulled over and just unplugged it. Now the ECU has to guess how much air is coming in, but it runs way better this way, for now.
Unfortunately, unplugging the AFM didn't fix the fuel gauge. It's still consistently reading backwardsly.
I did stop and pick up this Grande lava lamp that I find on the FB marketplace though. I have several lavas in my therapy office and the clients love them.
Baby for scale.
_________________ Dave Cook
President, Wild Westerner Club
1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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TDCTDI Samba Advocatus Diaboli
Joined: August 31, 2013 Posts: 12846 Location: North Carolina
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Posted: Sun Sep 19, 2021 11:44 am Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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Confused ECM, fuel gauge weirdness, have you checked voltage at driving speeds? A bad alternator, undercharging/overcharging, will cause all sorts of gremlins.
I just got a 2010 in with a bad alternator that charged 13.5 at idle & then went unregulated at 2,000 RPM, this caused most of the other systems to shit out, including the electronic steering assist & instrument cluster. I saw 19.2 volts & shut it down. _________________ Everybody born before 1975 has a story, good, bad, or indifferent, about a VW.
GOFUNDYOURSELF, quit asking everyone to do it for you!
An air cooled VW will make you a hoarder.
Do something, anything, to your project every day, and you will eventually complete it. |
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Xevin Samba Member
Joined: January 08, 2014 Posts: 7623
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Posted: Sun Sep 19, 2021 12:35 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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Useful help right here Dave I know you will swap it yourself. Safe travels brother. Loving the photo’s. You have any OREOs left
vwwestyman wrote: |
I may be looking to Subaru the hell out of this bus.
More later. |
1-800-SKILLS
For Subie conversion
Or
1-900-SKILLS
For his football betting advice.
Or
1-900-SKILLET
For his look into the your future
Or
1-900-SXXXILLS
For erotic conversations
Link
_________________ Keep on Busin'
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
Clatter wrote: |
Damn that Xevin... |
skills@eurocarsplus wrote: |
I respect Xevin and he's a turd |
SGKent wrote: |
My God! Xevin and I 100% agree |
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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vwwestyman Samba Member
Joined: April 24, 2004 Posts: 5688 Location: Manhattan, Kansas, USA
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Xevin Samba Member
Joined: January 08, 2014 Posts: 7623
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Posted: Sun Sep 19, 2021 3:13 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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Dang me!! Get home safe buddy.
Link
_________________ Keep on Busin'
67rustavenger wrote: |
GFY's Xevin and VW_Jimbo! |
Clatter wrote: |
Damn that Xevin... |
skills@eurocarsplus wrote: |
I respect Xevin and he's a turd |
SGKent wrote: |
My God! Xevin and I 100% agree |
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Back to top |
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Abscate Samba Member
Joined: October 05, 2014 Posts: 22639 Location: NYC/Upstate/ROW
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Posted: Sun Sep 19, 2021 3:18 pm Post subject: Re: WTF fuel gauge suddenly reversed operation: A live trip report |
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That’s called “ closure”
The relief of the uncertainty is palpable.
Let us know how things go but remember , when you are all safe and the car is on the flatbed , it’s all good. _________________ .ssS! |
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