Pagoda SL Group

W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: merrill on July 20, 2023, 15:54:13

Title: fuel needle bounce then stays on "empty"
Post by: merrill on July 20, 2023, 15:54:13

so this is interesting.

last weekend the car 66 230 was at half tank, decided to fill it up and take it for a drive.

after a spirited drive for a few miles the fuel gauge needed started bouncing from full to empty
occasionally staying at full then not.

today i took the car for a drive and the needle bounced then stayed at empty.
just for fun i removed the fuel cap to make sure there was not any pressure built up and since then the needle stays on empty.

wondering if i just got some bad gas...

maybe this weekend i will pull the fuel float and check it with an ohm meter and look for any corrosion.

any tips would be appreciated
merrill

Title: Re: fuel needle bounce then stays on "empty"
Post by: BobH on July 20, 2023, 16:06:13

Hello, a huge amount written about faulty fuel gauges and senders, could be a bad sender, a poor earth/ground, or a problem with the wiring loom or the connections, have a search for "fuel gauges"
Lots of posts and advice

Title: Re: fuel needle bounce then stays on "empty"
Post by: lreppond on July 20, 2023, 18:39:13

I’ve experienced similar erratic jumps with the fuel gauge. My situation isn’t as dramatic as yours. When I do a fill up, it registers correctly but as I’m driving the bouncing does occur “on occasion” especially on bumpy roads and inclines.   I have always felt it had something with the fuel float. I’d appreciate if you’d report your findings. 

Title: Re: fuel needle bounce then stays on "empty"
Post by: rwmastel on July 20, 2023, 22:35:16

Quote from: merrill on July 20, 2023, 15:54:13

any tips would be appreciated

You're a Full Member, so the below links are a great place to start.  After the below light reading soaks in and you feel confident about your subject matter expertise, search the forums to learn from the issues others experienced.

https://www.sl113.org/wiki/Fuel/SenderUnit
https://www.sl113.org/wiki/Electrical/FuelIndicator

Title: Re: fuel needle bounce then stays on "empty"
Post by: lreppond on July 20, 2023, 23:04:58

Thanks Rodd…excellent suggestions. 

Title: Re: fuel needle bounce then stays on "empty"
Post by: merrill on July 21, 2023, 00:42:13

hello
thanks for the replies,  i will check the links.

i had a similar situation with my 98' c230.    got some bad gas and the fuel gauge was useless.
had to run a few tanks for exon premium thru it before the gauge worked fine.

i suspect bad gas since the gauge was solid until today. 

let the fun begin

Title: Re: fuel needle bounce then stays on "empty"
Post by: dirkbalter on July 21, 2023, 14:30:07

Quote from: merrill on July 21, 2023, 00:42:13

hello
thanks for the replies,  i will check the links.

i had a similar situation with my 98' c230.    got some bad gas and the fuel gauge was useless.
had to run a few tanks for exon premium thru it before the gauge worked fine.

i suspect bad gas since the gauge was solid until today. 

let the fun begin

I have to ask. What is the theory on bad gas effecting the fuel gauge?

Title: Re: fuel needle bounce then stays on "empty"
Post by: merrill on July 21, 2023, 15:12:10

usually water in the gas causes issues.

the fuel level sender is not sealed from the fluid so water can get in thro things off....

Title: Re: fuel needle bounce then stays on "empty"
Post by: merrill on December 22, 2023, 19:08:40

hello
finally got around to pulling the fuel sending unit

the metal tube that the float goes in had fallen off the assy and was loose in the tank.
well kind a,  it was standing straight up held up by the float rod and wiring.

unfortunately one of the wire is broken,

new unit on order