no performance over 2800 rpm...

Hello A question for all I have a F36 which has a starboard motor that out of the hole can maitain RPS's over 3000 RPM's for about1 Minuter then bogs down to 2800 RPms and lower... I initally thought this was a problem with the timing advancing and still could be but feel it is unlikely. I have upgraded mallory ignistions, and have lubed up the mechanics and it is moving freely.. I have changed fuel filters and this has not made a difference.. Fuel is clear golden color no settlement.. screen at the carb is clean...

The wierd thing is if I Idle the motors for a minute or more I can get them up over 3100 Rpms for another 40 -60 seconds..

what does this sound like to everyone Fuel vollume issue, carb problem timing?

how is fuel volume / pressure tested or do I throw a new pump on..

I don't think plugs would cause this??

Is the vent on your fuel tank operating properly?

what is the best way to test that?

I"m thinking anti-siphon valve or fuel valve/fitting air leaks.

You can check the tank's vent by temporarily loosening the filler cap. it will provide an alternative path for the atmosphere. Tighten when done.

You don't say how old the hull is - maybe air leak in old fuel hose like DD suggested.

Mark- could the loose cap trick be a way to get back home in a pinch? I don't have an extra anti-siphon valve on board, maybe not a bad idea.

Maybe some duct tape and a small slot facing towards the rear? "I picked a bad time to start smoking cigars on the deck".

If you had to...as you know, it presents a safety hazard so it would be the operator's choice.

As far as the anti-syphon valve going bad, I'd be inclined to just eliminated it if it acted up while out at sea. Then replace it, if needed, once back in the slip.

Hello,

I believe the problem the be the pickup tube, the problem does not happen with the other tank running, i did try venting it with the cap open nd it still happened...

a Mechanic Mentioned to remove the antisiphon and the screen on the bottom of pickup and run it without as it is not needed is this correct? i doubt it...

The screen is there to protect the pump from larger pieces of debris. If your tank is clean and your fuel supplier keeps his equipment clean, you don't need the screen. If you have a filter in front of the pump, the sceen is not needed.

Anti-syphon valves are known to go bad. The need for it is determined by your hull and its installed equipment. There's no reason you can temporarily remove the valve for troubleshooting reasons.