strange 1969 9.5 problems, can you help me troubleshoot?

[gintaras]

I have a 1969 9.5 hp Johnson model 9R69S

Sometimes the motor runs exceptionally well, other times, especially after a lot of use, it just falls flat.

The idle is pretty rough, but under throttle it runs great, and will run full throttle no problem, nice and smooth. But then for some reason unkown to me, it will start losing power under throttle, to the point of almost stalling, unless I pull ? choke.. At this point is is a bit of a challenge to keep it running, and idle is extremely rough. If I shut it off for a minute or 2, it is back to running nicely.
So, the 2 main issues are a rough idle and an unexplained loss of power after a nice full throttle cruise.

I have had this motor gone over by an outboard repair person, who cleaned the carb and put about 4 hours into it and couldn?t find anything wrong, and was able to reproduce the issue in his shop, he did say it had low compression.. we are not positive that being the cause, but it is the only thing he could suggest.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

ANyone have any ideas? Anyone have a similar experience?

 

[kenmyfam]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Check the following to begin with. Could be any or all of the following.
Compression
Spark
Fuel delivery
Spark plug condition.

Post results and go from there.
If it improves with the choke half way then I would initially suspect that the carb needs cleaning and rebuilding.

 

[Fuzzytbay]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Poor or uneven compression will show up as a poor idle condition. IF you have low compression, the numbers would help (compression test results) others here help diagonose if you should rebuild the motor.
Your problems could all be due to the low compression in your motor. As things heat up, in a normal engine, with good compression, the compression ratio stays the same in the cylinders, due to the rings expansion as much as the outer cylinder walls, and the piston . IF however your cylinder walls, are worn, or the rings have worn, then the compression ratio may fall even lower, so after an extend running period, the motor may act up even more.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Thanks for the replies, I will update the thread after I get the compression levels.. Too many projects, too little time...

 

[Rick.]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

I've got to ask. Is your tank venting properly? Best of luck. Rick.

 

[jmendoza]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Take cowl off, and see if it runs normally. If it does, you have the classic exhaust manifold leak this model was infamous for. Some here have solved it by drilling holes in the cowl, others have reapired the exhaust leak.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Hey everyone, again sorry for the lack of updates.. I appreciate the replies, and I came here for help, it was offered, so I am sorry for not responding right away..

It makes no difference if the cowl is on or off.. and, the problem has gotten so bad that I just cant use the motor anymore until I get a new one or fix it..

I did a compression test and they were both reading exactly 70 on the gauge.. does that constitute low compression? I had a high performance VW engine in the past that read about 90 across the board, so comparing to that, 60 does not seem low to me, but I am new to outboards.

I hope that with the compression readings I can be pointed in the right direction. Thanks so much again!

 

[Rick.]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

IMO 70 is not bad for a 9.5 . Is your tank vented? Rick.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

tank is not vented, should it be? I do believe it to be the original tank

 

[Daviet]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

Compression, spark and fuel is what you need to make your engine run.
Your compression should be a little higher, but it should run on what you have.
Since you can duplicate the problem in a test tank, check the spark with a timing light when it starts to act up to make sure you are not loosing spark.
If you have to use the choke to keep it running I would suspect a fuel delivery problem. Try pumping the primer bulb when it acts up, thinking a fuel pump. Crack the gas cap on your tank, thinking the fuel pump might be trying to suck a vacume. If none of that helps, I think you might have a carb problem.

 

[Rick.]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

tank is not vented, should it be? I do believe it to be the original tank

It must be vented. If you have the original steel tank then it vents automatically when you quick connect the fuel line to the tank outlet. Just to be sure about this next time it acts up remove the fuel cap and see if it smartens up. If it does, your tank is not venting properly. Rick.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

OK, thanks again for the replies..
I went out and checked spark, spark is good.
I took off the fuel pump and tested it by applying some suction to it while the intake part was in some water, that was good too.. I reinstalled it and tested it again by running the motor and then pulling the line to the carb, the fuel would pulse out nicely, so the FP is fine.. it did seem to run better with the cap off the tank, it started on the first pull, it would not idle with no throttle, but with a bit of throttle it would idle, but it would "cough".. idle idle idle, cough, idle, idle, idle, cough...

it did seem to run OK other than the coughing...

I suspect the guy that I took it too last year may not be as good as I was told, the same guy who told me I had low compression, he told me to run 32:1 but I see on these forums that it uses 50:1

Maybe I just need a good de-carb and a carb kit and float...

 

[Rick.]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

A carb. kit would not be a bad idea for sure. To get rid of that cough you need to open your slow speed needle about and 1/8 th. of a turn(counter clockwise) until the cough is gone. Give it a few seconds each time for the engine to adjust to the richer mix. Rick.

 

[Lion hunter]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

I would run the 50:1 mix before you try and adjust anything. There is no need to run 32:1 and I don't know if the mechanic who told you that was implying that 32:1 was better because you had low compression, but it's not. And that motor should run just fine on 70psi compression (especially since its even in both cyl.) I don't think I've ever gotten over 85psi on a pull start motor.

Once you have the right mix you can play with the mixture screws but I suspect that if you have good spark that the carb is ready for a rebuild. If you do that you also need to replace all the fuel lines . From tank to carb is best.

 

[floatingwoody2006]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

have you tried pumping the fuel line bulb when it starts to sputter? Some here know i am not a big fan of these outboards, but when they are running well, they are a nice motor.
also..make sure the motor isn't "shaking" enough to throw the carb adjustment out of whack..Have you looked for air getting into the fuel line thru a bad clamp?

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

well, I'll have a definitive answer this weekend, but I think I can get it running right after I rebuild the carb.. first thing that tells me this is that the float was swelled and the edge was catching on the inner edge of the gasket, the needle wasn't allowed to fully open.. second reason was that when I removed the brass seat, the threads were all gummed up, now I know gummed up threads are not going to matter, but that was evidence enough to me that this carb has not been inspected and cleaned like I was told..

I also changed the gas tank sender gasket, the original cork was leaking, I would like to change the float because it is gas-logged, but that is not important..

Boy I can't wait to get this back together, but I have a car project that needs attention tomorrow.. Hopefully I can have it running good and post a purring youtube video

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

The kit is pretty self explanatory but I do have a question.. should I pop out the old welch plugs and install the new ones? Why would I need to do this? Is it to better clean the carb with the plugs removed?

 

[floatingwoody2006]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

yes..clean it all out behind those plugs..Lot's of little bit's can hide there as well. It's simple to do. I just drill a very small hole being carefull not to go deep enough to touch anything, and pull it out with a pick. Some just punch thru em and do it that way.

 

[gintaras]

Re: strange 1969 9.5 problems, can you help me troubleshoot?

So I am about to clean out the carb and reassemble it, I have removed the welch plugs, but behind one of them is a plastic part that is not included in the kit. I tried to pry this part out, gently, i might add, but it wasn't moving.. it looks like there are some holes in the throat that could be cleaned by removing this piece, but I don't want to damage it and be stranded..

Is it necessary to remove this piece for cleaning? Why would the kit include the plug but not the plastic part?