volvo penta aq125 carb problems

[cpgraham122]

I have a volvo aq125 and when I go to the lake it fires up easy and runs great for 20 to 30 mins no issues at all then I will b runnin along at around 3000 rpms and all of a sudden it looses power the rpms drop to like 500 then back up then back down. If I let off the throttle it will idle fine. I have replaced the spark plugs plug wires timing belt, fuel , and fuel filter. I am not a mechanic and I know very little about engines but I think it is a carburetor problem. But before a buy a new carb or carb kit I wanted to see if anyone had any advice?

 

[sandkicker]

Next time this happens, unscrew the gasoline fill cap almost all the way. IF this fixes it, the vent to the gas tank is plugged.

 

[pugetsounder]

Another thought too is the advance system in the distributor might be sticky. Problems usually happen when going from idle and throttling up but it's an old motor and things happen. If the mechanical advance system didn't work at all your boat will still idle fine you just won't get it to rev up over 1000 RPMS or just above idle. You may have to pull the dizzy to get to the advance weights to see if they are rusty or corroded over but it is a fairly common problem in saltwater environments.

Along with Sandkickers advice always try the free tests first to rule things out.