89 454 7.4 Bravo fuel issues?

[Ysoloud]

I bought a great barn find, 1989 cobalt 222. The boat has 112 hours on it and yes I did all regular maintenance to start. The boat was garage kept and covered so when I opened the cover it looked like it was on a showroom floor, but the showroom needs to be able to move now. I'll start with what I have already done. Drained fuel and cleaned tank, new fuel filters, new cap and rotor, new carb. Here is the issue I'm having, boat runs great for about 15-20 min and close to 50mph with secondarys working fine, then will work great till about 3000rpm, if I try to open the secondary sometimes it will kick in and sometimes it will fall on it's face. No idea how it can run great for 15-20min and then not want to run over 3k. I'm guessing the fuel pump but would like to know you guys thoughts as well.
Thanks for any advice!

 

[tpenfield]

Welcome to iBoats.

Looks like you posted in the wrong forum, but the Mods will be along to move your thread to the proper forum (Mercruiser, right ?)

I believe that the secondary 'venturies' (barrels) on the carb open mechanically on your engine so it should be gradual (automobile versions may have used vacuum to open the secondaries, which give you a 'punch').

Post the serial number of your engine for more specific answers, but you can put a new fuel pump on it (make sure it is a marine type and connected properly to the carb (which is hopefully a marine type as well). Another thing would be to check the all electrical connections to the ignition system, since it was a barn find and not used in quite some time.

 

[alldodge]

Howdy

Being an 89 and if it's a Mercruiser then iy should have a mechanical fuel pump. The pump would be my first thought, and you need to get a pressure gauge on it to see if you can get 4-7 psi. I would also check your oil and see if it's getting over full. If the pump leaks it can leak full into the oil pan.

Next things would be the fuel tank vent. If the vent is clogged the pump will pull a vacuum and eventually not be able to draw fuel.

Next would be the antisiphon valve on the tank. Its a barbed fitting which the fuel line connects to going to the filter. There is a spring loaded check valve inside