1971 Johnson 9.5 problem today

[joho5]

Took the motor out today to run it for the 2nd time since I rebuilt the carb. The last time I took it out, it ran fine. Idled fine and ran fine open. Today, not so much. What it would do is when I opened it up it would barely start to go...maybe for like 20 yards or so, then it sounded like something would then catch and it would go somewhat fine. It was mainly at the beginning when trying to start out. Then after that it would just seem to run a bit bogged down. Like I said, last time it ran fine and that was fresh off the carb build so I thought it was good to go and then today, not so much.

I know nothing is dirty in the carb because I spent alot of time cleaning that thing and saw all the jets cleared. I have the rich setting set fine. The boat idles fine and sounds fine in neutral. When I did a carb rebuild, I also did a fuel pump rebuild. The only thing I can think possibly is the fuel pump isnt working like it should and being inconsistent. After I rebuild the fuel pump, the manual says you should be able to blow in the input, but not blow in the output. I couldnt blow in the output, which is correct, but I could blow in the input but it was a little tough. Not just completely free. I would think that would be the problem, but last time the motor ran good.

if anyone has any idea on what to check or to do, let me know.

thanks

Matt

 

[tashasdaddy]

Re: 1971 Johnson 9.5 problem today

a carb can get a bit of trash in it at any time. flaking of the interior of the fuel line, anything. it takes very little to foul those little jets. have you ever replace your hoses.

 

[ezeke]

Re: 1971 Johnson 9.5 problem today

Check your flywheel key. I hope you used a good torque wrench.

 

[mchin]

Re: 1971 Johnson 9.5 problem today

My experiences with the OMC 9.5 is that it takes very little to foul up the carb, keeping it from operating properly. Much less tolerant then many of their other motors. Did you remove and clean the high speed jet?

 

[joho5]

Re: 1971 Johnson 9.5 problem today

Yes I removed the whole thing and took it completely apart and cleaned everything I could possibly get to.

ezeke, I am a noob, what is the flywheel key and what do I need to check?

thanks

 

[joho5]

Re: 1971 Johnson 9.5 problem today

I am going to replace the whole fuel pump and see if that helps...I am weary about it being hard to blow air through it. It makes me think the gas is having a hard time getting through the pump and which might be causing the inconsistence. Maybe sometimes it gets through fine, and then sometimes the pressure keeps it lacking.

my bulb does stay firm though and no I havent changed the fuel lines lately...maybe thats a job to do as well.

 

[kbait]

Re: 1971 Johnson 9.5 problem today

These particular motors (lowboy 9.5's) are notorious for having a shift-shaft rubber bellows (just above lower unit, and you must pull powerhead to see) fail. I got a fix from a knowledgeable fellow on here, if that's it. To test, run it until failure. Pull the fiberglass cowl (cover) and run and see if it fails. If it still fails, then you don't need me. If it runs great, then it's probably a split-up shift shaft bellows in the lower leg of the motor, just above the lower unit It lets exhaust gas (low in oxygen) flow up to carb intake.. poor running result. There is an excellent workaround for that problem w/o powerhead removal, and total chassis teardown! Email: kirbysbait@mchsi.com if you want me to hook you up w/the dude and his fix kit ($15 after ship). I used one w/perfect result! He's a wizard. Good luck!