No fuel at high throttle coming from tank.

[CapeAngler239]

Hey all. I have a 2008 Mercury 150 Opti. I have a problem with fuel not getting to the motor at high speed. The tank is a used but good tank I replaced old one with. New hoses, for vent and fill, and I believe there are no kinks on the hoses. Also put new hoses outside going to motor with a new water separator and quicksilver primer bulb. I do know there was no ball bearing on the pick up tube to anti syphon. I can run all day at high rpm on a portable. Any suggestions on what to look for?

 

[Vernon351]

Vent line clogged or obstructed ? Or cap isn't venting maybe

 

[CapeAngler239]

Vent line clogged or obstructed ? Or cap isn't venting maybe

New lines were put in.

 

[Chris1956]

Are you using 3/8" fuel lines? Does the fuel pickup tube in the tank have a clogged screen?

Sometimes a screen and or A-S valve are hidden in the fuel pick up tube. Also, make sure fuel pickup tube is 3/8" also.

 

[CapeAngler239]

Are you using 3/8" fuel lines? Does the fuel pickup tube in the tank have a clogged screen?

Sometimes a screen and or A-S valve are hidden in the fuel pick up tube. Also, make sure fuel pickup tube is 3/8" also.

Sorry forgot to mention, pick up tube is brand new as well, and yes the lines are 3/8 brand new ass well. I noticed that if I disconnect the fue line before the water separator, and before in goes into the hull towards the tank, the line is dry where you would expect some fuel to spill out. As I mentioned there is no A/S valve at the tank currently? Could it be that fuel is running back into the tank? I don’t see how it could since the tank is higher than the fuel outlet port at the stern, but it could be?

 

[Chris1956]

Your water separator is full of fuel right? it should have no air in it.

Other than that it sounds like air leaks into the fuel line.

 

[CapeAngler239]

Your water separator is full of fuel right? it should have no air in it.

Other than that it sounds like air leaks into the fuel line.

Correct. The water separator is full and clear of water. The problem with air in the line is that I use the same line on a portable tank and it runs perfect all day at all rpms. I installed a new anti syphon fitting at the tank, and again made sure bent is free of obstructions. New lines from tank to motor. Pick up is clear of debris, and it still looses power at crushing speed of around 3500 to 4000rpm. Switch to the portable, not a single hiccup. It’s driving me up a wall.

 

[QBhoy]

Is true fuel water separator newly fitted ? They are uni directional with arrows on the top usually. If your pick up pipe wasn’t new I’d say that was picking up crap from the tank at high demand rpm.

 

[dsiekman]

I’m fighting a very similar issue. Incredibly frustrating.

I am starting to wonder if the fuel water separator fitting is somehow clogged. I have not run a new vent but tried running with the fuel fill cap off. Better but not perfect. You might try that to rule out the vent.