New Syncro Sending Unit - Only reading 1/2 full on a full tank

[thomast]

I have a new sending unit in my 86 Syncro w/SVX and since the install, when I fill the tank, it only reads 1/2 full. I just completed a 2000+ mile trip and it was consistent the entire trip. I thought maybe after a few fills it would correct itself (wishful thinking!). Any ideas what might be the issue?

Thanks!
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1986 Westy Syncro SVX
1970 Bay Window

[4Gears4Tires]

The sender is the issue. I have the same problem. I have the old sender too, but that job is a PITA so I'm just gonna tolerate my wonky gas gauge and try to remember to use the trip odometer for double checking.
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'87 Syncro Ferric Oxyhydroxide Superleggera Edition
'85 Westy Sciuridae Domus Edition

[MarkWard]

Did you buy the aftermarket sender or the VDO one? GW accidentally sent me the aftermarket one and while it fit, it was completely wrong on the sweep. I contacted GW and they noticed their mistake and sent me the VDO OE one.

Fortunately I had the tank out and was able to watch the sender float move through it's range.

It would be difficult, but you may have somehow looped the return hose over the float.

Check the orientation too. There are photos in the gallery showing the correct orientation. I believe the return tube is at about 2 o'clock. Hope that is of some help.

[dschaftlein]

I recently installed an aftermarket sending unit from Cip1. It Doesn't work at all.

I still need to find the time to troubleshoot.

[djkeev]

If full reads 1/2
Is 1/2 tank reading 1/4?
Is 1/4 tank reading 1/8?

If so, I wonder if there is a resistor or something you could wire in to correct the information being sent to the gauge?

Dave
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[thomast]

Thanks for the replies. It's an aftermarket sender.

djkeev - From a full tank (reading 1/2), the gas gauge travels down to empty and sits on empty for an additional 100+- miles. I never ran out, but would fill up usually putting in about 16 gallons. I think the tank is just over 18 gallons.

Guess I'll go read all the remove/install sending units without removing the tank threads...
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1986 Westy Syncro SVX
1970 Bay Window

[Zeitgeist 13]

D'oh, I recently replaced a Syncro fuel sender with an aftermarket unit from GW, and it didn't fix the dead gauge issue. It needed to be replaced due to rust, but I assumed it would also fix the inop situation. Wrong assumption, which might be compounded by an iffy unit. FML
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'89 Bluestar ALH w/12mm Waldo pump, PP764 and GT2052
'01 Weekender --> full camper
y u rune klassik?

[MarkWard]

If you unplug the sensor with the key on, jump the sensor connector and the gauge should peg full. There is a thread about gauge testing without the factory tool using specified resistance. Hard to add links on my cell phone.

[Bassyaks]

I still have 8 gallons once the needle reaches "E" , the job sucks so I live with it.

[outwesty]

The JP aftermarket syncro sending units are garbage. I made the mistake of installing one when I couldn't get the VDO one. Tschroeder0 had the connector on his break off while on a trip which caused a fuel leak and he had to JB weld it on to get home. Getting them to read correctly is another story. Hook it up to your meter. The range will be far off from the VDO one.

[Zeitgeist 13]

[4Gears4Tires]

[MarkWard]

I get that it's a pain to deal with. For those that might come across this thread. Aside from my tip above to check for full sweep of the fuel gauge, you can take your new sender out of the box and plug it into the van. Work the float across the range and the gauge should full sweep.

The problem I ran into with the aftermarket sender was that the orientation was such that installed the float was not square to the top and the bottom of the tank. I had the tank out and could look in the filler neck hole with a flashlight and see the sweep was wrong. I could have "straightened" it with minor effort I believe, but at the time I thought I had purchased the the VDO one.

So, it's not that the aftermarket sender won't work, but might need some massaging assuming the manual test of it is good. All to often aftermarket parts seem to need massaging. The details are the tolerances. Exact tolerances cost more time. I don't fault a reseller. Unless customers let them know what is going on, how would they know? It just sucks that the syncro is assembled at the factory around the fuel tank.

[dgbeatty]

There is a very similiar LOOKING sender from another VW model that fits just fine. Trouble is the resistance readings when operated are reversed. Carefully study the part number and test the sender before installing one.
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