lost all power in my 70 hp

[bob johnson]

after a few issues I finally got the 1989 70 running somewhat good... I suspected a high speed power issue and bought a 13 pitch prop and took the boat 6 hours away to give to my son. My first trip out to show him the boat and the controls was the first time using the prop. previously I could only rev to 5200 rpms with my 15 pitch. now there were 2 people in the boat even with the 13 pitch and it was a dog out of the hole and it had no GET and GO...but it eventually planed out and I got the rpm up to 5500....but were were probably only going about 20-22 mph.... it was snotting rain and miserable so we didn't spend much time out but playing around on the way back in...it just died out....it didn't stall....but the rpms were totally lost....idling along if you shoved the throttle forward...nothing changed in the motor...I just seem to lose advance and power.... I suspect I lost spark in one or two cylinders.... we idled back to the ramp...it was difficult to try and trouble shoot in the wicked rain and super shallow bay....it must have only been about a foot of water almost anyplace I went..( it was my first time there).....there were docks and a ramp...but the channel must have been super narrow... so close to the ramp.... the motor was tougher to restart... if I gave it throttle, it would start.....but id have to throttle down and then shift quick to get moving...( a few days ago I turned a screw to back off the idle because on the muffs it was idleing at 1100 rpms...but in the water it dropped a lot....so I know I need to reset that screw......)....I dropped it off at the only place open I could find that worked on outboards....its an auto shop and boat repair place... so they haven't looked at it yet...but im asking here what might the possibilities be.... the compression was excellent....when I bought the motor a few months ago...and it had good spark.... I might have lost the spark....I did lose spark when I was playing musical controls as I had several controls which all had issues... thought I cleared it up and the last time I checked I had spark in all cylinders............bob

 

[flyingscott]

That motor should got to 6000 rpm what kind of boat is it on?. Have you done a link and sync? Have you tested the fuel pump? Is the VRO still hooked up. With a cylinder down they usually will not hit 5000 rpm.

 

[bob johnson]

ok that's good info....I was thinking it shouldn't rev to 5200 if I was missing spark.... I have NOT done a link and sync.... my regular mechanic wouldn't work on it, because he thought it was too old and hed just be chasing issue after issue....and all I wanted him to do was go over it and verify its running condition....have NOT "tested" fuel pump... the VRO is plugged off and the alarm disabled.