Fuel tank lines mercruiser 3 litre lx

[Hori1965]

Hi everyone been having trouble with my engine playing up after it’s warm and not staying in idle
I’m starting with fuel
I have taken photos of my tank and lines and expecting to see return valve and anti siphon valves
Are they actually got to be unscrewed off my tank when I remove the hoses
One turns but does not screw out and fuel line one won’t even turn and I don’t want to snap it off
Any help appreciated

 

[Chris1956]

Antisiphon valve is in third picture, or at least that is a prime candidate, and where it is usually installed.

Are those red hoses marine rated? They look like garden hose. You might look to see if they are still in good shape on the inside.

 

[Hori1965]

Antisiphon valve is in third picture, or at least that is a prime candidate, and where it is usually installed.

Are those red hoses marine rated? They look like garden hose. You might look to see if they are still in good shape on the inside.

Thanks mate
The red hoses don’t look like Garden hoses to view from boat they look heavy duty even more so than the fuel supply hose “black hose front of tank “
Do these connections undo from the plastic tank or will I snap something trying
Cheers

 

[alldodge]

Welcome
I would say the fittings will unscrew but they may crack the tank.

Suggest trying to find out without removing the fittings just yet.

Connect the fuel line from the tank with a Tee fitting. Attach a vacuum gauge to one side and a fuel pump to the other. Run the pump and see how much vacuum you get. If its not much more then 1/2 in Hg I wouldn't worry about it

 

[Hori1965]

Welcome
I would say the fittings will unscrew but they may crack the tank.

Suggest trying to find out without removing the fittings just yet.

Connect the fuel line from the tank with a Tee fitting. Attach a vacuum gauge to one side and a fuel pump to the other. Run the pump and see how much vacuum you get. If its not much more then 1/2 in Hg I wouldn't worry about it

 

[Hori1965]

Thanks mate will try tomorrow

 

[Grub54891]

Those fuel lines look like air hose to me. Not rated for fuel?

 

[Chris1956]

Heater hose maybe, but not marine rated fuel lines to my untrained eye.

 

[Bt Doctur]

should only have 3 fittings for fuel hose, the largest one is feed. guessing the red is 3/4 or 5/8 vent hose next to the fill hose (3rd pic)
(4th pic feed) no AS fitting though

 

[Candy Gramformongo]

(1) "One turns but does not screw out" -- This tells me the interface between the tank and one of the female fittings is loose and unsealed. Prime opportunity for leakage and explosion.

(2) The main fill hose appears to be dated from 1997, long overdue for replacement.

(3) I think I would just go ahead and remove the tank, clean it out, and fix everything properly with marine grade hoses. Then troubleshoot your running problem, if it still exists.

And maybe buy some lottery tickets, because you are lucky guy!

 

[Chris1956]

Fittings are usually molded into plastic tanks. If they swivel in a bushing, they might be able to be drilled out, but if rigid in the tank wall, removal will likely damage the fuel tank.

I am assuming the third small hose is for a fuel return from the injector rails.