124 fuel tank issues

[nick.ged]

i am convinced that my fuel tank partially blocked. i am not sure what mechanisms are inside it. the outlet is underneath and appears to have a threaded bung used to attach the rubber outlet pipe to the tank. does anyone know what is inside, is there a strainer something else that may be partially blocked?
also when i open the filler, there is often a hissing sound, i cant work out if it is air rushing in, indicating a blockage on the breather and vacuum in the tank, or air rushing out indicating pressure in the tank, how does the system work on the 124?

also the fuel filter is after the pump, i have replaced it, but would like to add one before the pump, but think this may cause problems with the feed to the pump, if it is gravity fed...

 

[6pot]

i am convinced that my fuel tank partially blocked. i am not sure what mechanisms are inside it. the outlet is underneath and appears to have a threaded bung used to attach the rubber outlet pipe to the tank. does anyone know what is inside, is there a strainer something else that may be partially blocked?
also when i open the filler, there is often a hissing sound, i cant work out if it is air rushing in, indicating a blockage on the breather and vacuum in the tank, or air rushing out indicating pressure in the tank, how does the system work on the 124?

also the fuel filter is after the pump, i have replaced it, but would like to add one before the pump, but think this may cause problems with the feed to the pump, if it is gravity fed...

Mine hisses when i release the fuel cap if shes empty.

 

[nick.ged]

yes, that is what is bothering me, as there is almost a full tank in there,i never run it below 1/4 due to turbos, and risking lean running.

 

[kth286]

it can be air in/out and is normal for all 124s.

however if the charcoal canister inside the N/S wing is blocked and has not been changed at the 72,000 miles service interval, it has been known for the tank to start collapsing/imploding.

 

[tippandy]

Hi, you don't say why you think its blocked. Have you checked the purge valve on the near side inner wing ,it can become blocked with rust particles from the charcoal cannister mentioned earlier.

ANDY

 

[grober]

There is a strainer at the fuel outlet of the tank which can be renewed if necessary. It is pretty difficult to get at.You don't want any restriction before the pump in case it cavitates. Since it uses the fuel to cool and lubricate it during operation the pump will be damaged if it overheats.

 

[nick.ged]

i think its blocked because i have a 345 lpm pump and a pressure regulator, when the engine is idling it is set to 42 psi. recently power has dropped off and when i rev the engine the pressure should rise in relation to boost, ie 42 psi and at say 6psi it sholuld read 48 psi, but it is droping, causing the engine to go lean. not good cause at 15 psi, it will melt like chocolate.