Merc 5.7 Q Jet fueling issues

[Bnewton530]

Hey guys, I’ve been having an issue with my boat where it will start and run fine, and I can run about for a while at throttle but after a short time on the gas, it’ll bog out and die as if it is out of fuel. After that I can only idle with the choke pinned closed for a bit before opening it back up. After that it starts over where I can run a round shortly befor it bogs and dies.
I have replaced the fuel pump and rebuilt the q jet. The float is set right at 1/4” and mixture screws at 3 turns out. When it runs, it runs very well. Any ideas?

 

[alldodge]

Check your gas tank vent line. When it bogs down, open the gas cap and listen for air being sucked in. If that does help

Check your antisiphon valve on the tank that the rubber fuel line is attached and goes to the filter. The valve can get crud build up and need replacing

Can also get a gas can and place the fuel line in the can to see if it helps

 

[Bnewton530]

Check your gas tank vent line. When it bogs down, open the gas cap and listen for air being sucked in. If that does help

Check your antisiphon valve on the tank that the rubber fuel line is attached and goes to the filter. The valve can get crud build up and need replacing

Can also get a gas can and place the fuel line in the can to see if it helps

Thanks for the reply. I’m going to check the antisiphon and the vent hose today. It tends to spray fuel out the filler neck when filling up so I’m optimistic that those two may be a problem.