Loss of power - 74 Johnson 85 HP

[TheOrigionalSteve-O]

Hi, Im a new boat owner, purchased a 1974 galaxie boat with a 1974 Johnson 85hp motor with "Power Shift II" in July.spent til the end of august rebuilding the transom. I used the boat for labor day weekend. The boat ran great the beginning of the first day then it started stalling out and was difficult to get going seemed the idle was too low. docked the boat for the day. Started right up the next day ran great, pulled a a skier the put the tube on and there was no power. Full throttle I could only go 5 mph was at 25 - 30 before. I took the boat out and decided I would wait for spring. Any Ideas? Additional info. Boat was in storage for 3yrs. I changed the lower gear oil. Never thought about changing the plugs (had run great). I did run thru a tank and 1/2 (fresh gas n oil) Thanks for any help

 

[sangerwaker]

Re: Loss of power - 74 Johnson 85 HP

3 years in storage? Did it appear to be pumping a good amount of water? My concern is that the impeller has dried out and hopefully not fallen apart inside the pump housing. If you haven't done so, I would pull the lower unit off, and check out the water pump condition.<br /><br />I would also do a compression test. If the motor has gotten too hot, there could be some "internal" damage to the motor. A compression test should show over 100psi on all cylinders. They should all be within a few percent of each other also.

 

[TheOrigionalSteve-O]

Re: Loss of power - 74 Johnson 85 HP

Well finally removed the lower unit to check out/install a new impeller. The impeller was intact in matter of fact it appeared to have been replaced at some point in time. The rubber was still soft. Decided that since it was apart that I would replace it anyways in addition to other various gaskets/o rings that came with the kit. Guess it's time to do a compression test. If that checks out ok , any ideas what else it may be? Thanks

 

[TheOrigionalSteve-O]

Re: Loss of power - 74 Johnson 85 HP

Finished replacing impeller (used rebuild kit). Also checked compression. all cylinders were around 120. Decided to check screen filter in fuel pump. It was clean. Any suggestions where to go from here?

 

[Basscat 1]

Re: Loss of power - 74 Johnson 85 HP

Im not sure what your are saying the problem is with your boat? When you say loss of power, what is the rpm's?<br />I have the same engine on mine, so maybe I can help. 120 on all cyliders is good.

 

[TheOrigionalSteve-O]

Re: Loss of power - 74 Johnson 85 HP

Doesn't have a tach. But boat seemed to idle ok, but when giving it throttle there was a lack of power..kindof bogged down like there was a lack of power. Prior to that I had pulled a water skier fine. I put new plugs in it and installed a new fuel line last night. I'm going to run it tonight on water ears to see how it seems. I plan on lake testing it Sunday if it seems ok. I also noticed that someone bypassed the fuse located above the rectifier diode. The holder is still there. What does this fuse control? What size fuse is it? Thanks for any help.