1980 70HP loses power

[djeady]

I may have his resolved, but I am still curious. Put my boat in checked everything over and went out for a run. Boat started beautifully, but after about 10 minutes started to bog down under power.

Thought at first it was fuel so cleaned my large canister filter - there was gunk and water in there, but no change. Boat would run fine after sitting a bit, but then would lose power. Tried a portable tank - still the same.

Pulled the plugs and found that the top 2 were a beautiful tan colour and dry and the bottom one was black and wet. Checked the ignition coil resistance on both primary and high voltage and everything was fine.

Put it all back together and now it seems to be running well - the only change I made was to relocated the high tension lead to the lower cylinder as I thought might be contacting the cover lock.

Could it really be that simple? I'll keep tabs on it over the next couple of days.

I have one other problem which I wondered if it might be related. The motor keeps blowing its main fuse when I start it - usually before I even turn the key to engage the solenoid.

I am suspecting that this is caused by a faulty ignition switch and is unrelated to the other problems. Can anyone offer any other suggestions?

Thanks

 

[tashasdaddy]

Re: 1980 70HP loses power

you have a short in the ignition circuit. could be in the harness, or inside the control box. if you are arching to the latch, it is time for new spark plug wires.

 

[5150abf]

Re: 1980 70HP loses power

Concur, I have an 81 50 and it had an intermittent miss, pulled the hood and looked put the hood back on and it ran fine, then it would screw up again.

I ended up rewiring the engine, 30 year old wires are kinda brittle, and rerouting plug wires and it went away so that is a good place to start.

 

[djeady]

Re: 1980 70HP loses power

Re-routing the hight tension lead to the bottom cylinder seems to have done the trick.

Now I just need to find a new ignition switch and see if it resolves the main fuse problem.

 

[5150abf]

Re: 1980 70HP loses power

I would geuss the main fuse problem is related to the 30 year old wires I mentioned, mine was giving me some weird problems till I rewired it.

I cut the wires 3''-4'' back on the engine side of the big red plug one at a time and replaced them all, haven't had a wiring issue since.