outboard motor help please

[MISKO]

ok here is the scoop ... the motor is a 1979 75hp johnson sea horse .. if I go outside right now put the muffs on .. turn the key she will fire right up and run full bore all day in the driveway .. as soon as I put it in the water it will start and idol .. as soon as I give it throttle it dies out or putts no speed .. I have rebuilt the fuel pump , replaced all the vacuum hoses, and replaced the fuel bulb .. IDK

 

[fordman84]

ok here is the scoop ... the motor is a 1979 75hp johnson sea horse .. if I go outside right now put the muffs on .. turn the key she will fire right up and run full bore all day in the driveway .. as soon as I put it in the water it will start and idol .. as soon as I give it throttle it dies out or putts no speed .. I have rebuilt the fuel pump , replaced all the vacuum hoses, and replaced the fuel bulb .. IDK

Doesn't make sense to me, but I'm not a boat engine guy. Maybe under a load it craps out. Have you tried filling a trashcan with water, lowering your engine into it in your driveway and trying that? I remember my grandfather doing that to test his out.

 

[MISKO]

havent done that ..

 

[fordman84]

Someone will chime in with help. Edisto maybe?

 

[MISKO]

Someone will chime in with help. Edisto maybe?

edisto gave me a few ideas

 

[fordman84]

edisto gave me a few ideas

bump

We have enough boat guys, someone chime in. I don't have a boat right now, but I love to listen and learn.

 

[MISKO]

lol

 

[Edisto_Tiger]

make any headway on this yet?

 

[Wingingit]

When you had the boat in the driveway running, were you putting water into the impeller? Or were you running it dry?

If dry, you're already going to need to replace the impeller blades, might also be the original problem, that engine is water cooled and by not cooling it with lake/sea water (which is also the impeller blades lube), you probably have lower motor problems.

If your not framilar with the bottom end of the motor, suggest taking it in, unless your a fair mechanic already, then read up on the Impeller blade assembly and replace-it.

If you ran it dry for more than a minute or two, replace the impeller...period.