1967 9.5hp johnson lost power

[jwhewell]

Just replaced the fuel pump with an "excepted" substitute for the original type(doesnt exactly look like the orig.)...well it worked great for about 10 outings then yesterday just coming down the river and my power went away. When not engaged you can rev it up and it will get louder. But when in fwd/engaged you can only go so fast and it will only get "so" loud no matter how far you turn the handle. Primer pump seems to be primed the entire time. Any help is greatly appreciated.

 

[ezeke]

Re: 1967 9.5hp johnson lost power

You are probably running on one cylinder. Try pulling one spark plug lead at a time to see which is the problem, then investigate step by step.

 

[jwhewell]

Re: 1967 9.5hp johnson lost power

ok thanks. I will check that out today. Do you think that the gas tank not having the vent open could have contributed to that? I have run it in the past and not even thought about the vent and had seen the gas tank collapsed kind of, but no power was ever lost. I checked the vent and it was closed; and when I opened it it allowed some air to come in....it had been 2 days since out on water. I was also told that the reed valves might be effecting that...the source was not what I would put great validity too though. thanks again, the river water has seeped into my veins and I need my fix!

 

[ezeke]

Re: 1967 9.5hp johnson lost power

Not having the vent open will cause the floats bowls to run dry when the fuel pump cannot overcome the vacuum. You may notice that the primer bulb will usually collapse.

At that point the running engine will run lean and then eventually die from lack of fuel. Running lean is bad for the engine because it overheats it and running without the oil from the fuel mix makes it worse.

 

[iwombat]

Re: 1967 9.5hp johnson lost power

Always leave the vent open when you have the tank connected to the motor. The fuel pump isn't strong enough to fight a vacuum in the tank.

Forget about the reeds theory.

 

[tashasdaddy]

Re: 1967 9.5hp johnson lost power

i'm voting a coil crapped out. but could possibly be fuel starvation, with the vent closed.

 

[jwhewell]

Re: 1967 9.5hp johnson lost power

yep, I have boiled it down to the coil/s(or possibly the spark plug wires themselves??). I indeed was just utilizing one cylinder. One spark plug would get hot and the other was cool. Any crucial info as where to purchase and removal/installation is appreciated.

 

[Rick.]

Re: 1967 9.5hp johnson lost power

At the top of this forum there is a file called "Top Secret File". There is a post in it about removing your coils. What do yours look like? They may have been replaced already. If they are cracked you should replace them but take a good look at your points too as they could also be your problem. If it's a plug wire going to ground try firing your motor in the dark and you will see the arc. Best of luck. Rick.

 

[ezeke]

Re: 1967 9.5hp johnson lost power

Start with the easy stuff, cracked porcelain insulator for instance and, the spark plug wires have to be solid core. Swap the spark plugs and see if the problem follows.

 

[jwhewell]

Re: 1967 9.5hp johnson lost power

ok heres the "new" deal: compression top=58-60psi bottom=55-60psi; take the top wire off plug and motor dies...take bottom off and motor acts as if nothings wrong; top plug is dirty(ish, its new) you can tell its "working", and the bottom looked as if it hasnt heated up at all, but it smelled of fuel. took plugs out and put fingers to holes and got equal +/- amounts of fuel on fingers. Had a buddy put hands/fingers on both wires and there was juice on both. he he Replaced both coils...new plugs...switched condensers/capacitors...proper gaps on plugs. not entirely sure on the points gap?? but i did take an emery cloth to them and then a peice of paper.

Starts fine...runs fine; havent taken it out on water to see if power came back after new coils...just figured it wouldnt.

Well I hope you fellas can stear me in the right direction; got the ex coming next thursday to go fish and maybe rehash things, so having the boat in tip top order would be a plus. Thanks again guys.
Jason

 

[Rick.]

Re: 1967 9.5hp johnson lost power

Well your going to have to check and see if you have spark now. If you do you don't have a problem. If you don't I would re-check the plug wires where they attach to the new coils to make sure you got the pin centered into the wire core. Also you could try switching your plugs. The point gap is .020 and very important. Let us know. Rick.

 

[freddyray21]

Re: 1967 9.5hp johnson lost power

if you had no fire to one plug and now have fire to it then more than likely the problem is solved. You do also want to have the vent open. compression seems low, but if it is running fine probably a bad guage. Friend of mine has a cheap gauge and is alway borrowing mine as his will read 20-25 lbs lower than my Craftsman.

 

[jwhewell]

Re: 1967 9.5hp johnson lost power

I investigated further and found a spark plug wire to be broken about 70-80%. So if youve worked on this model you know the wire goes underneath and wraps around then pops up where the coil stabs into it. I ran a new wire to the coil; and I wasnt able to figure out if this rectified the problem due to the fact that I appearently screwed the throttle asssembly up. Dont know how, but now it doesnt want to move....idle or rev up. It is hard to turn the handle, and the brass fitting at the base (where it actually goes inside) doesnt really move when I can turn the handle some. The motor still starts and you can manually turn the "disc" that moves a peice connected to the carb, but with some difficulty??? Anybody ran into this problem?
Jason

 

[Rick.]

Re: 1967 9.5hp johnson lost power

Back the thottle off as far as you can then shift to neutral. Also check the adjustable thumbwheel disc (hows that for part identification) on the very outside of the tiller arm hinge. If it is rotated too far in you loose throttle movement. Rick.