9.5 HP Johnson idling poorly

[SeaNymph Man]

I am experiencing a poor idle from my 9.5 HP Johnson. When it is idling,I hear
what sounds like either a miss or a spitting through the carb type of noise.
It will do this about three times and then stall if I don't advance the throttle
immediately. Also,is it possible I may have a vapor lock? She will not get on plane(barely does it to begin with on a boat rated for 25 HP)at all on full
throttle when it is very hot and humid out. I have just about had it with this particular Johnson,...I am not getting along with this 9.5 motor at all.

 

[Rick.]

Re: 9.5 HP Johnson idling poorly

I'll pay the shipping if you want to give it to me. I was going to say it is a problem with the slow speed needle setting and then you went and threw in the part about not getting up to speed. Darn you made it more complicated. What is some history here? Has it regularly performed better at high speed than what you report it is doing now? My first guess is it is time for a carb. kit and a very thorough cleaning. Beyond that , you should do the normal things like a comp. check and a spark check. Pull your plugs and see if the need re-gaped or replaced. You may even want to change the points and condensers or at least clean and re-gap the points. Still my best bet right now would be a carb. problem. Best of luck. Rick.

 

[F_R]

Re: 9.5 HP Johnson idling poorly

I'll pay the shipping if you want to give it to me. I was going to say it is a problem with the slow speed needle setting and then you went and threw in the part about not getting up to speed. Darn you made it more complicated. What is some history here? Has it regularly performed better at high speed than what you report it is doing now? My first guess is it is time for a carb. kit and a very thorough cleaning. Beyond that , you should do the normal things like a comp. check and a spark check. Pull your plugs and see if the need re-gaped or replaced. You may even want to change the points and condensers or at least clean and re-gap the points. Still my best bet right now would be a carb. problem. Best of luck. Rick.

Agreed, spitting back through the carburetor is a classic symptom of running too lean. Or, an air leak into the crankcase from anywhere. But I wonder if this is something new, or part of a longer existing problem. Have you ever been happy with the motor? It sounds like you have not been. Has it ever planed the boat like you think it should? Maybe it just isn't enough horses.

Also, I have to ask the year of the motor. 1964 and 1965 models never did idle well, even when brand new. Newer models were ok, but there are a host of problems unique to the 9.5 that show up from wear and tear and just plain old age. One common one is broken front motor mounts. Can you move the powerhead fore and aft? A small amount of give from the rubber mounts is normal, but gross movement is a broken mount. It won't idle well if it is flopping around in there.

 

[SeaNymph Man]

Re: 9.5 HP Johnson idling poorly

Agreed, spitting back through the carburetor is a classic symptom of running too lean. Or, an air leak into the crankcase from anywhere. But I wonder if this is something new, or part of a longer existing problem. Have you ever been happy with the motor? It sounds like you have not been. Has it ever planed the boat like you think it should? Maybe it just isn't enough horses.

Also, I have to ask the year of the motor. 1964 and 1965 models never did idle well, even when brand new. Newer models were ok, but there are a host of problems unique to the 9.5 that show up from wear and tear and just plain old age. One common one is broken front motor mounts. Can you move the powerhead fore and aft? A small amount of give from the rubber mounts is normal, but gross movement is a broken mount. It won't idle well if it is flopping around in there.

The motor is a 1970 model. I am wondering,like you,if the spitting back through the carb at idle might have been an existing problem. It barely planes the boat. I think it's biggest problem is that it is too small for the boat that it is installed on as far as HP is concerned(the boat is a Sea Nymph
14R rated for a max. of 25 HP). You can move the powerhead just a little
fore and aft. With just me in the boat most,if not all,the time I figured it would be fine when I bought the boat(the motor I have came with it BTW),
but the motor fell short of my expectations. I also noticed this past week that while it has been very hot and humid in my area,the motor has not performed very well. It seems to run better when the air temp is cooler,but
still performance is marginal at best. I have not been all that happy with the motor since I have had the boat. I was not able to lake test the boat before buying it,...no lake was nearby so I had to settle for a 'test tank' run of the
motor. I need to look for at least an 18 HP motor for this rig to perform as I
feel it should,...I'd like to have a full 25 HP,though!

 

[Nobody]

Re: 9.5 HP Johnson idling poorly

Have you looked around on sites like youtube for vids of 9.5s in action? There are several on there that helped give me a good baseline for what to expect from a properly tuned 9.5 on my 14ft tin bathtub, when I first took mine out I had ignition issues and was only firing on 1 hole most of the time, now that I've cleared up those issues it will plane the boat with 2 people and 180lbs of trolling batteries if the water conditions are right.

Given that the HP rating on the 9.5 is about 7hp by today's standards the boat will never be a speed demon.

 

[Lion hunter]

Re: 9.5 HP Johnson idling poorly

MY 9.5 will move my 12' about 18mph. Have you ran it in the water with the cowl off. Can you see fuel spitting out anywhere on the carb? Have you inspected or replaced all your fuel lines? Look at the link below and see if it helps. Mine would idle fine and run for a little bit at WOT then the problems would start. Oh, and i'm 99.999999% percent sure that it ain't vapor locking. I have only ever seen one true vapor lock in my life and I don't expect it would happen on rubber fuel line.


http://forums.iboats.com/showthread.php?t=324841

 

[ezeke]

Re: 9.5 HP Johnson idling poorly

Like F_R suggested, I think you are running lean. That's usually because of the lean rich needle being inproperly adjusted, or that the needle, seat, or packing have problems.

 

[SeaNymph Man]

Re: 9.5 HP Johnson idling poorly

MY 9.5 will move my 12' about 18mph. Have you ran it in the water with the cowl off. Can you see fuel spitting out anywhere on the carb? Have you inspected or replaced all your fuel lines? Look at the link below and see if it helps. Mine would idle fine and run for a little bit at WOT then the problems would start. Oh, and i'm 99.999999% percent sure that it ain't vapor locking. I have only ever seen one true vapor lock in my life and I don't expect it would happen on rubber fuel line.


http://forums.iboats.com/showthread.php?t=324841

It has just occurred to me that I read a recent letter to the editor in
Bass&Walleye Boats magazine,...guy described a similar problem he is
having with his 70 HP Evinrude. The tech editor who answered his
question mentioned the possibility of a chipped reed valve causing
the spitting through the carb and the rough idle. I am begining to
wonder if that may be a possibility with my motor,...given it's age
and all.

 

[Nobody]

Re: 9.5 HP Johnson idling poorly

If your 70 is like mine (and if mine is correct) the reed blocks should be real easy to pull as they are right under the carburetor, the 72 I have appears to be much different in this area.

Here is a pic of one of the reed blocks from the 70, you can see light getting through one of the leafs which according to the service manual is bad, this motor still runs pretty good though while I wait for parts.

I have the leaf plate PN as 0302031 and the whole block as 0379689.

 

[floatingwoody2006]

Re: 9.5 HP Johnson idling poorly

i feel your pain man..I also have a 1970 9.5 in similar shape. I have been thru Everything on this thing, and it just will not run well. I have cleaned / adjusted points, new plugs, new spotless carb, you name it..and the darn thing just isn't right. I would like to kick the designer right in the shin on this one. It's the only motor i have had that i cannot get right.

 

[spunkyjr]

Re: 9.5 HP Johnson idling poorly

Well I guess I'm not alone. My 64 Johnson does the same thing. It's ok as long as it's run wot but don't slow down and try to troll or it will stall. It will get you from point A to B as long as your not in a hurry. Put it in neutral and you have to keep giving it throttle to keep it running. Tried new plugs, new fuel pump, points and condenser. Still runs terrible.

My 87 9.9 ran like a champ. I use to put on around 5-600 hours a year on that motor from the day I bought it until last year when it died. Only changed the fuel pump once and plugs 3 times a year. You could idle that motor down so it ran at around 1/2 mph. To bad the lower unit went.

 

[SeaNymph Man]

Re: 9.5 HP Johnson idling poorly

Well I guess I'm not alone. My 64 Johnson does the same thing. It's ok as long as it's run wot but don't slow down and try to troll or it will stall. It will get you from point A to B as long as your not in a hurry. Put it in neutral and you have to keep giving it throttle to keep it running. Tried new plugs, new fuel pump, points and condenser. Still runs terrible.

My 87 9.9 ran like a champ. I use to put on around 5-600 hours a year on that motor from the day I bought it until last year when it died. Only changed the fuel pump once and plugs 3 times a year. You could idle that motor down so it ran at around 1/2 mph. To bad the lower unit went.

Am I reading this correctly,...5-600 hours a year? I can see 50 -60 hours,...
but 500-600 hours? If so,then you must have run the heck out of that motor!
My motor will be okay as long as you have it in neutral and keep giving it
throttle like you say to keep it going,otherwise it will stall like yours does.
Fine at WOT,but lower than that,she runs rough! This has got to be the
worst motor Johnson ever made,...surely they made motors far better than this 9.5 from 1964 to 1974. Horrible running motor at idle especially.

 

[Rick.]

Re: 9.5 HP Johnson idling poorly

SeaNymph Man: Have you spotlessly cleaned the carb. and put in a new carb. kit? There is something wrong if it won't idle slow. It will probably be (as suggested before) that it needs to be a richer mix of fuel/air and is currently running on the lean side by your description. The kit will come with new needle packing washers which could also be a solution to the problem. If adjusting your slow speed needle is having no effect then your carb. is probably dirty or your needle is in need of replacement. If boat is rated for a 25HP engine there is much doubt in my mind a 9.5 is even in the ball park for the boat. Perhaps the previous owner didn't care about planing and just used the 9.5 for other reasons.

I have a 1973 and I was trolling for hours yesterday between 1.7 and 2.3 MPH. I'm not getting good top end speed from it but that's another story. The boat was heavily loaded. It may well have trolled slower but I didn't attempt to. Evinrude made these motors from 64 to 73 so I'm sure they must have been dependable or they would have fixed the design. Best of luck. Rick.

 

[Nobody]

Re: 9.5 HP Johnson idling poorly

I would do a basic compression and ignition (spark) test on the motor before buying a carb kit, if you don't have access to the equipment for these tests (I'm not sure if the major autoparts places rent compression testers) or know someone who has the tools then as suggested by others several times in this thread I would start with a carb kit and see what you get from there.

For reasons unbeknown to me my 9.5s run fine at low speeds in a bucket, the idle isn't great but having gone from a good running motor to a not so good running motor and back the differences in performance from various fixes were obvious without having to put the boat in the water every time.

A properly tuned 9.5 on a 14ft boat will never be much of a thrill ride but if anything you might be able to increase the resale value on it a lot with a small investment in parts and time.

On a slightly different note - your boat is probably rated for a 25hp 2 stroke which is anywhere from 40 - 50lbs lighter than an equivalent 25hp 4 stroke engine, the extra weight of a 4 stroke can be hard on the transom and weight distribution becomes very important. A buddy of mine had a 14ft Valco (25hp rated) with a 25hp 4 stroke and it was scary, too much motor for that boat in my (and others) opinion.

 

[SeaNymph Man]

Re: 9.5 HP Johnson idling poorly

SeaNymph Man: Have you spotlessly cleaned the carb. and put in a new carb. kit? There is something wrong if it won't idle slow. It will probably be (as suggested before) that it needs to be a richer mix of fuel/air and is currently running on the lean side by your description. The kit will come with new needle packing washers which could also be a solution to the problem. If adjusting your slow speed needle is having no effect then your carb. is probably dirty or your needle is in need of replacement. If boat is rated for a 25HP engine there is much doubt in my mind a 9.5 is even in the ball park for the boat. Perhaps the previous owner didn't care about planing and just used the 9.5 for other reasons.

I have a 1973 and I was trolling for hours yesterday between 1.7 and 2.3 MPH. I'm not getting good top end speed from it but that's another story. The boat was heavily loaded. It may well have trolled slower but I didn't attempt to. Evinrude made these motors from 64 to 73 so I'm sure they must have been dependable or they would have fixed the design. Best of luck. Rick.

I have a buddy at work who can probably do the carb work. He tinkers with his 85 HP Evinrude on his 1978 17 Ft. Procraft bass boat,...so surely he could help me out on the carb for my motor. However,...even with a carb cleaning
and everything else you mention that we should do,still the 9.5 is still too
small for my boat,and performance would still be marginal at best. But a 25
on my boat may scare me to death,...a 15 may be just enough for just
myself in the boat,...but no more than 20 HP. As you said,...the previous owner must not have cared whether it planed out or not with that 9.5 motor.
Maybe they used it as a trolling motor! For me,...too small for the bodies of water I frequent,...such as large reservoirs.