No Power under Load

[jeepin75]

ok, here is my situation, I have a 1978 johnson 70 hp outboard. it ran real good till 4th of july. it started to have problems getting up and going. i put a timing light on it and found the middle cylinder wasnt firing and narroweed it down to the coil. i changed that out and it runs like its never run before so good, so responsive and just sounds great. before my test drive today i noticed black goo comming from the front side of the prop. i found that that was all the unburnt stuff from that cylinder coming out. but after it was in the water it just had no power when i tried to floor it. in neutral its awesome and if i tilt the motor out of the water and put it in gear its still awesome. but with the drive iin the water i put it in gear and floor it and it only goes to about half the rpms. i checked the butterflys and there opening all the way, checked the fuel filter and lines its getting fuel. it just doesnt have the tourque to push the boat. i hope it will be a cheap fix, anyone who can help please do, its nice outside and i wanna take it out!!!!!!!! thank you very much ROB

 

[JB]

Re: No Power under Load

Howdy, Robabot.<br /><br />You have probably dropped a cylinder again.<br /><br />Pull each plug wire while the engine is at idle. If rpm drops that is a good cylinder. If there is no change that one is dead. <br /><br />If you have good spark to a dead cylinder, try squirting some fuel mix into that carb throat. If that picks it up, overhaul that carb.<br /><br />If you have no dead cylinders, try pumping your primer bulb when trying to go to WOT. If that brings the engine on, check out your entire fuel supply train. If there are no restrictions or air leaks overhaul your fuel pump.<br /><br />Let us know what you find.

 

[BKool68]

Re: No Power under Load

Are you sure that goo behind the prop was not your lower unit lube?

 

[jeepin75]

Re: No Power under Load

Ok first yes im sure its not gear oil cause i just purged it and its still clean and it doesnt even have the right viscosity or texture as gear oil, now the big one.<br />i found out its my middle cylinder, pulling the wire had no effect on rpms, i switched plugs wire and coils with the other cylinders and still have the same problem, its getting some voltage through it using a meter, but cant realy tell if its enough, i tested it with an extra plug and i cant get a spark out of it. not sure were to go from here except to change that little computer thing. are there any ways to test it or fix it, im prety mechanicaly inclined so i hope so .

 

[jeepin75]

Re: No Power under Load

ahhhhhhhhhhhhhhh

 

[JB]

Re: No Power under Load

Hi, Robabot.<br /><br />First, invest $30 in a manual. It will guide you through checking out your ignition system and tell you when you need to go buy parts.<br /><br />Good luck.

 

[jeepin75]

Re: No Power under Load

ok, ive been trying to find a manual but havent been able to find one for my motor. i got a couple of ideas from a guy at work, im ghonna try them tomorrow and see if they pan out thanks for the help guys

 

[jeepin75]

Re: No Power under Load

yeah, i trouble shot the problem down to my cdi unit. i tested the stator by switching the 2 wires coming from the stator and the problem was still in the same cylinder so the stator was fine, i then switched the 2 wires going into the cdi for the #2 and #3 cylinder and switched the spark plug wires for the number 2 and 3. i then fired it up and the problem thern moved from the number 2 cylinder to the number 3 cylinder. so through deductive reasoning it is the cdi unit. the capacitor in it for the number two cylinder isnt giving the number two coil enough juice to fire the plug. i just have to wait till payday to get the new part, good news is i found one right down the block and it was 110.24, not to bad ill post one more time after its all back together to give some final thoughts on the whole problem. thanks fellas rob