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Seems like people are making this more complex than it needs to be....
In order to check to see if the tank is venting the air properly, from the primary tank to the filler neck (via hose #12 in your picture above), it seems like it would be pretty simple to remove the rubber plug on the 944 sender and fill the tank until fuel comes out of that extra steel line, on the sender.
At that point, there's only two choices:
1. If fuel comes out through that "extra fitting in the sender" and the gauge reads full, hose #12 is pinched off.
2. If the fuel comes out through that "extra fitting in the sender" and the gauge does not read fuel....there is something wrong with the sender or gauge.
Worth noting, hose #12 (in the picture above) gets installed backwards 90% of the time. Just looking at the tank, It appears that the hose fits one way, but in reality, it fits the other way.
I've fixed dozens of cars with this very problem, which have had this hose installed the wrong way.
There a short side and a long side on each side of the hose. Install it backwards (long side to the tank) and the hose will pinch off about 2" from the tank and will not allow the tank to be filled.....100% of the time.
Yeah, I see that you blew compressed air through the hose....but compressed air will force the hose open. No pressure (just venting) will not allow the hose to "unpinch".
Seems like people are making this more complex than it needs to be....
In order to check to see if the tank is venting the air properly, from the primary tank to the filler neck (via hose #12 in your picture above), it seems like it would be pretty simple to remove the rubber plug on the 944 sender and fill the tank until fuel comes out of that extra steel line, on the sender.
At that point, there's only two choices:
1. If fuel comes out through that "extra fitting in the sender" and the gauge reads full, hose #12 is pinched off.
2. If the fuel comes out through that "extra fitting in the sender" and the gauge does not read fuel....there is something wrong with the sender or gauge.
Worth noting, hose #12 (in the picture above) gets installed backwards 90% of the time. Just looking at the tank, It appears that the hose fits one way, but in reality, it fits the other way.
I've fixed dozens of cars with this very problem, which have had this hose installed the wrong way.
There a short side and a long side on each side of the hose. Install it backwards (long side to the tank) and the hose will pinch off about 2" from the tank and will not allow the tank to be filled.....100% of the time.
Yeah, I see that you blew compressed air through the hose....but compressed air will force the hose open. No pressure (just venting) will not allow the hose to "unpinch".
Hope this helps!
Great suggestion, thank you Greg. I will check back in after I try that.
Seems like people are making this more complex than it needs to be....
In order to check to see if the tank is venting the air properly, from the primary tank to the filler neck (via hose #12 in your picture above), it seems like it would be pretty simple to remove the rubber plug on the 944 sender and fill the tank until fuel comes out of that extra steel line, on the sender.
At that point, there's only two choices:
1. If fuel comes out through that "extra fitting in the sender" and the gauge reads full, hose #12 is pinched off.
2. If the fuel comes out through that "extra fitting in the sender" and the gauge does not read fuel....there is something wrong with the sender or gauge.
Worth noting, hose #12 (in the picture above) gets installed backwards 90% of the time. Just looking at the tank, It appears that the hose fits one way, but in reality, it fits the other way.
I've fixed dozens of cars with this very problem, which have had this hose installed the wrong way.
There a short side and a long side on each side of the hose. Install it backwards (long side to the tank) and the hose will pinch off about 2" from the tank and will not allow the tank to be filled.....100% of the time.
Yeah, I see that you blew compressed air through the hose....but compressed air will force the hose open. No pressure (just venting) will not allow the hose to "unpinch".
Hope this helps!
Read the statement below.
Greg wins the gold star 🌟
> Pulled the cap from the second vent port on the Uro part as suggested, and vented it via fuel line into my favorite Ehrlenmeyer flask. Tank immediately accepted more gas and filled to an indicated 4/4. Uro 944 fuel level sender in a 928 with the second vent port (not on OEM 928 senders) vented into a flask
So I learned that despite blasting air, fishing wire, and pulling lot of stuff apart, Occam's Razor wins again. Again thank you Greg and mrmerlin and others for the suggestions.
As warned by Jerry, Greg and others, the line was installed backwards by a previous owner. Also, found a mass of shellac-like detritus in the line. Thus, pinched off and yet shop air would blow through,, giving a false impression while installed that the vent was clear. Thanks all for inputs, very appreciated.
Detritus shellac in the Porsche 928 fuel tank vent line.
NOTE did you remove the small metal float stop in the new sender?
this is a thin piece of wire placed into the side of the sender through a small hole it keeps the sender from going full travel.
NOTE I would also remove the plug on the other unused port of your new sender,
and put a piece of hose that is plugged and use clamps
NOTE that plug is not a secure way to stop fuel,
once the tank is hot and the pressure builds the plug could be pushed off,
then if the tank has enough fuel in it it will pour out. Or this will will happen when you fill the tank
Update IDK if the 944 sender also has this wire inserted I think it does.
That said it would be smart to plug the new sender in and turn it so the float goes to the top and see what the indication does before you install it into the tank.
Also it could be possible that the new sender is sealed so the float will only rise so far and thus an air bubble prevents the sender from topping out
@Mrmerlin, what is the right way to cap the hose? Is there a part or method that you can recommend. Google results were all over the place on this topic. Thank you.
12-12-2020, 11:21 PM
