25 johnson wont run past idle

[DougyB]

Re: 25 johnson wont run past idle

When you say not the plugwires, I take it you mean that the plugwires are never to be crossed, always used to the spark plug directly next to/ parallel to it
?. My only other question is the orange wires that plug into each coil, do you leave them with their original coil, or do they get removed from the coil and stay with their original positioning? ie. the orange plug that runs to the top coil, should it either stay with whichever coil that plugs to the top cylinder, or stay with the coil it started in?

 

[DougyB]

Re: 25 johnson wont run past idle

And should it be able to start when flipping coils? Because I have been getting backfires

 

[AlTn]

Re: 25 johnson wont run past idle

yes..orange wires stay in their original positions..orange/blue tracer is on top < blue sky >..orange/green tracer on bottom < green grass >...starting?..they'll start and run on 1 cylinder, HOWEVER, if the bottom coil is bad and it's swapped to the top AND the powerpack is defective yielding the orange/green wire with low or no voltage, then you end up with a coil on top that's no good and the wire to the bottom coil that's no good...and no spark at either and no start and this is where the cdi testing procedure comes into play...I ran into this situation on a '78 9.9 and just replaced both coils and the powerpack as there was no evidence that any of them had ever been replaced

 

[DougyB]

Re: 25 johnson wont run past idle

AlTn, the sky/grass theory is just what I needed to fix the backfire and do a more thorough test. This sounds very funny to me, but the other day the engine would die when I removed the bottom plug. That bottom coil will not shoot a gap of 7/16ths, whether placed on top or bottom. I did some more testing today, and the same coil still won't shoot a gap. However, for some reason, it will start the engine on that one cylinder thats not shooting the gap. Pretty odd, and should be used as a rule of thumb that plug pulling is just nothing more than a quick test to do when your spark tester is not on hand. If I had not bought the tester and went off of todays results, I would have thought I was getting sufficient spark into the cylinder, when indeed I wasn't. I will buy a replacement coil, and hopefully this will be the end of my troubles. I'll post results to let everyone know.

One question I do have however, by only replacing one coil, will that put any strain on the old coil? AKA piston replacement theory...

 

[AlTn]

Re: 25 johnson wont run past idle

separate circuits for each through the powerpack HOWEVER I don't know enough about electronics to tell you with any certainty that there can be no "bleed over" effect within the circuits

 

[DougyB]

Re: 25 johnson wont run past idle

well guys, i got the new coil, have a spark in both gaps, took it out to the water, and... dissapointment. It finally got up past the low rpms, i got it on a plabne, and when i backed off the throttle just a tad it died. Started it back up, it hesitated accelerating, hesitated decelerating, and then stalled. After that one more quick run about 50 yards about mid throttle and it shut down and would not idle for more than 5 seconds without shutting off. It was giving me hicup sounds once in a while, whole nine yards.

Checked spark again, both coils are still shooting the gap. My prime is good, gas is good, carb has fuel in it, jet cleaned. Could it be the powerpack, even with both coils jumping a gap? When a powerpack goes, does it often take a coil with it? Maybe this is why my one coil is bad? Im clueless

 

[AlTn]

Re: 25 johnson wont run past idle

is this a tiller handle rope or electric start, remote steer rope or electric start? the exact model no. in your post doesn't show up at marineengine.com

 

[DougyB]

Re: 25 johnson wont run past idle

its an electric start, J25tecdc, 86

I swapped in a new powerpack, its running now but is having hiccups somewhere. I'm not sure whether to start a new post as my problem has changed, but ill put the details in now

View attachment 145948View attachment 145949

I get the ball primed tight, engine starts easy, but idles a little rough sometimes. At random moments of acceleration the motor will bog down, sometimes dieing and sometimes picking back up after a bit. Cuts out at random rpm ranges, mostly mid to full.

Notes to make: Since opening the air valve in the gas tank, the prime bulb does not lose its prime much at all, stays tight running and while sitting. Powerpack swapped out, as well as the one coil that wasn't firing. The carb I bought got completely rebuilt, it was for a prior year model but had the same throat diameter, etc. I removed the orifice plug and installed the plug from my years carb ( clean and brand new, installed correctly with jet screwdriver tool.. 47 to a 49) Put a new fuel pump in last season after a piece of plastic snapped off in cold weather while I was replacing the fuel lines.

Does the fact that my bulb is staying tight elimate a fuel issue? Idk if there was an air leak if the bulb would stay solid or not. I'm not sure what it could be, but any ideas are greatly appreciated.

 

[AlTn]

Re: 25 johnson wont run past idle

did the engine shut off completely by itself, or did you shut it down with the key once it started to cut out and come off plane?