Moeller fuel anti siphon mercruiser dies at cruise

[Hooligan]

Hey guys, just looking to post up some information here that could have saved me some time with diagnosis of a problem I had (that consequently had me pulling my hair out...) and will hopefully save someone else some time.

Bought a new old stock Moeller below deck tank and installed with new lines to my mercruiser 5.7. Engine starts right up and purrrs like a kitten. Take the boat out for a ride and it gets up on plane, then stalls out as soon as it flattens out. Start boat. Repeat. Notice boat runs great with no issues under 2K rpm. Ten mph back to dock. Over the next few trial runs same result. Motor sounds perfect, starts and goes thru RPM range on trailer. Still dies on water under load and is not predictable. Some times it runs at cruise for 30 seconds, sometimes 2 minutes.

Spend next precious free days testing the fuel pump, carb, ignition, blah blah blah. Talk to a friends uncle who spent a fortune on a similar problem and he tells me "damn $8 part was screwing everything up" (anti siphon barb on tank). So I take the tank hatch off and proceed to take off fuel barb. Barb has almost no flow when blowing air through. It looks fine, but no good flow. Replaced with regular brass barb from West Marine for $5 (surprised its not $10) and take boat out. Runs GREAT! Tops out, flawless mid and top end. Much happier now that the problem is solved.

I hope this helps someone out.

Unfortunately for me, my alpha drive leaked all the fluid out on that first successful run at cruise and top end (used unit) and canonballed itself. New drive on order from SEI. One of these days this boat will run pissa and Ill post some pictures up.

Until then: Ride on brothers.