Please Help, Out of ideas

[chriscraft87]

I just purchased a 87 Chris Craft with a 3.0 OMC Inboard outboard.
1st couple of trips out i had to get towed back to the boat ramp. . .
Boat will run good for the first 30 min then start to die down at high rpms, like its begging for fuel. So I replaced all the Fuel lines from the fuel tank to the fuel pimp and from the pump to the carb.
Also rebulit the Carb.
Ran it today, same problem. .very frustrating. It will idle just fine, and does ok at low rpms.
What else could be wrong.
the Gut I bought it from just put new points, Plugs, and a coil on it. It sat in storage for about 2 years, he said he drained all the old gas and got the motor running before I bought it.

 

[Eric 3.7LX Alpha 1]

Re: Please Help, Out of ideas

fuel tank vent blocked, causing a vacuum in the tank after the 30-min time? Try unscrewing the deck fill see if any changes.

 

[elkhunter338]

Re: Please Help, Out of ideas

install a temporary fuel pressure gauge at the carb to make sure you are getting fuel pressure at the carb. the vent idea is a good one to check. aRe you plugging a fuel filter after 30 min.
If your boat has a fiberglass tank, eth fuel will eat up certain fiberglass tanks. Could be plugging the fuel filter.
Maybe the pickup tubes are plugging up, mine have screen on the bottom of them.

 

[chriscraft87]

Re: Please Help, Out of ideas

I'll check out my vent line tomorrow. Plan to take the boat out tomorrow and see how it does.
Friend of mine says it may be vapor locking, from everyone ive talked to they say you can put a clothes pin on the fuel line before the carb. Im going to try that and see if it helps.


I did put new filters on the fuel pump and the carb. Mine has a fiberglass tank, the pick-up tune does have the screen on it. I blew it out when i replaced all the fuel lines.