470 mercruiser stalls at WOT

I recently got a 1978 470 mercruiser I have shift problems.. It does not want to come out of gear when in the water, I thought it was a bad shift interrupter switch but the switch does kill the motor when pushed, so maybe it is a bad shift cable?? not sure but now my problem is it will run fine at cruising speed around 3000 rpm. but when I try to open it up all the way it slowly gets bogged down and stalls completely. could this be related to the shift problem or is it another issue? the carb was just rebuilt also..
thanks
Nick

Re: 470 mercruiser stalls at WOT

sounds like 2 problems, shift cable and a fuel restriction

Re: 470 mercruiser stalls at WOT

Here is how to test the boats fuel system. between the tank and the fuel pump.

http://forums.iboats.com/showthread.php?t=167561

Re: 470 mercruiser stalls at WOT

thank you for the quick replies.. ok heres what I found. the boat would idle forward fine and then what used to happen only at wot was happening at anything over about 2000 rpm... so I look at the motor while someone is driving and notice oil covering the motor and inside the carb.. the hose from the valve cover to the top of the carb, (flame arrestor) is spitting out oil right into the carb.. so I disconnected the hose and ran without it and the motor runs fine, and it did stop spitting oil.. the hose just recirculates exhaust gases correct?? what would cause oil to back up into the hose.. is it possible it was overfilled or the filter failed?? I just got the boat and have not changed the oil yet since i was told it was done recently and it looked clean, I am changing it now. but not sure if I should run without the hose hooked up or if I dont see any more oil I guess ill hook it up and see how she runs..
anyway thanks for your help, I am new at boating and this site has already helped me a lot..