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1971 9.5hp Evinrude with lean idle

guido2

guido2

Regular Contributor
Just bought this little Jewel from an old timer......its very low hours, 65 lbs compression. Runs great at fast idle, mid, and full power. At idle will lean "spit" at me. Just like low needle is plugged or too far closed.

It will shut down motor if you close low speed needle to 1/2 turn or less. I've been through spark and great "snap" to 1/4th inch.

Rebuilt fuel pump, tried new tank and hose. Even tried a completely different carb air horn.....upper portion with another needle valve.

Checked gaskets above reed valves and removed reeds and tested performance and seal on them. They were fine.

Motor is clean and virgin condition, but I replaced all hoses and including little intake to crankcase tube.

This lean idle problem has me "stumped". Note: I'm running motor in test tank without cowl in place as any "stubby" is going to run rich in the test tank if you keep cowl on.

Primer bulb stays hard so I know fuel pump is strong.

Any help would be greatly appreciated. Thanks...Tim
 
Re: !971 9.5 Evinrude with lean idle

Joe, JWB, Vic........anybody!!!!! Help please!
 
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Re: !971 9.5 Evinrude with lean idle

Examine s/speed needle valve tip for wear, if a groove exists, any adjustment will be quite difficult. Clean carb on general principles.

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.

When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.


Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
 
Re: !971 9.5 Evinrude with lean idle

Thanks "farnsp" and Joe. I'll try checking both items. I have another needle valve to try first. The crank seal will be suspect if another needle doesn't help.

Note: I have refaced needles using a drill or drillpress too.

I don't think it could be the valve seat as I have tried two different carb bodies.
 
Re: !971 9.5 Evinrude with lean idle

Two sets of needles and bodies. Whats the chances of both being worn the same amount? I'd think you'd see some change. Half the motors I see need the upper seal replaced to get it to idle. All of them need the carb cleaned so it's a toss up. For the seven bucks for a seal, it's short money.
 
Re: !971 9.5 Evinrude with lean idle

Hi, I didn't have a chance to try anything yet, but I think your right. I've been working on a 1973 75 Johnson with carb ailments. Will post you on the results. Thanks, Tim
 
Re: !971 9.5 Evinrude with lean idle

Does your 9.5 run better when you put it on half choke?

Mine does, and I have the exact same problem as you.
 
Re: !971 9.5 Evinrude with lean idle

thx

That half choke thing is a sure sign of a dirty carb. Clean and rebuild that carb. Take a peice of stranded wire and twist a couple of strands together and use it to clean/scrape all the little holes/passages in the carb. Blow it out with compressed air. Use carb cleaner. Set the float so it's parallel with carb body when flipped upside down, and moves freely without getting "snagged" when you move it with your finger. Ignore the high speed setting, on your motor as it is fixed.

Gas... clean carb
Spark... should jump accross a 1/4" gap
Compression... even compression on both cylinders

Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle va /lve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, wating for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out.
 
Re: !971 9.5 Evinrude with lean idle

farmsp..... If you're qoing to quote and print anything I've written, please quote and print it in its entirety. The first quote above does not list where you got that information and comes across as paraphrasing. The second part is cut off right after the Initial Setting mention and would lead someone to think that this is all there is to setting a dual adjustable needle valve carburetor. It should have read:

(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)

Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.

Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.

Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.

Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.


Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
--------------------------------------------------
(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral.

Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.


Thousands of parts in my remaining stock. Not able to list them all. Let me know what you need and I'll look it up for you. Visit my eBay store at:

http://stores.ebay.com/Evinrude-Johnson-Outboard-Parts-etc?refid=store
 
Re: !971 9.5 Evinrude with lean idle

I've cleaned that carb multiple times now. Guess one more time can't hurt.

Though, when I installed the needle valve above the float, it tends to stick.

I have a new needle valve with the head for that little clip, but since the original didn't have it, I don't know how that clip is supposed to sit.

Any pics?
 
Re: !971 9.5 Evinrude with lean idle

Sorry Joe,

Obviously I didnt paste your quote right. No harm meant. I didnt read it after I posted it. Not out to steal anybody's quotes. Tried to pass on information. It wont happen again.
 
Re: !971 9.5 Evinrude with lean idle

Farnsp..... No offense intended. Passing on information (quoting) is okay with me as long as it's not abbreviated in any way that might cause confusion, etc. Others do it, I do it myself from time to time..... no problems and glad to have you onboard.
 
Re: !971 9.5 Evinrude with lean idle

I put in a new needle valve with the clip that keeps it tethered to the float.

Will have to put it together and put it in the test tank and see what happens.
 
Re: !971 9.5 Evinrude with lean idle

The engine no longer runs better when I half choke it. So, clean carb I guess.

But it still runs poorly.

Anybody know of a decent tach that could be installed on this motor?

I need to know what kind of RPMs it's running.
 
Re: !971 9.5 Evinrude with lean idle

Hello farnsp, where do I get an upper crank seal for $7.00? Glad you and Joe worked it out..........Joe is a true professional and wants to "get it right".

Thanks Joe and farnsp, but I still think its a crank seal.....just been too busy to order a couple seals.

Let me know pls. the best source for them......need one for a 1960 10h.p. too......probably the same type.
 
Re: !971 9.5 Evinrude with lean idle

I see what you mean, thing must be made of gold. Your seal 309733 goes on this site for $18.15. I just picked up a crankshaft seal for an 18hp and it was 7 and something. Seirra doesnt offer that seal, so it looks like you're gonna pay threw the nose for it. Try your local dealer.
 
Re: !971 9.5 Evinrude with lean idle

These motors are prone to exhaust leaking under the cover and contaminating the intake mixture. Does the motor run better with the cover removed???
 
Re: !971 9.5 Evinrude with lean idle

Yeah, I am familiar with the exhaust problem. Actually idles better with cover in place which richens the mixture. I ordered the seal from this site, thanks.....$18.00. The other seals we are talking about are simply a quality o-ring. The retainer made of a bakelite type material is quite expensive, however......$25. This is available yet at OMC. Thanks, Tim
 
Re: !971 9.5 Evinrude with lean idle

Be sure to let me know how that motor runs after you get that seal changed.

Also, what rpm are they supposed to run at idle?
 
Re: !971 9.5 Evinrude with lean idle

Ok, will do, the seal should arrive today. Idle rpm should be maybe about as fast as you can swing your finger in a circle or about 400 rpm if your good.
 
Re: !971 9.5 Evinrude with lean idle

LOW - SPEED NEEDLE ADJUSTMENT
(1971 JOHNSON 9.5 HP SERVICE MANUAL)
a. Turn needle valve clockwise until it closes and seats. DO NOT force needle against seat, as the taper on the needle may be damaged.
b. Turn needle valve counterclockwise 3/4 turn.
c. Start motor
NOTE:
Allow motor to reach normal operating temperature by running in a tank with test propeller at one-half throttle or slightly more for at least 5 minutes before proceeding to the next step.
d. With motor in gear, run at full throttle briefly to clear motor out. Keep engine in gear and retard throttle to idle position (700-750 rpm) and slowly lean low-speed needle valve by turning clockwise until motor hesitates or spits slightly; then enrich setting by turning counterclockwise to where the motor runs the fastest and the smoothest. Allow 15 seconds for the motor to respond to adjustment.
e. Replace low-speed adjusting knob set midway between lean and rich. Be careful not to disturb position of needle while installing adjusting knob.
f. Adjust idle adjustment knob so motor will idle at 550 rpm IN GEAR.
 
Re: !971 9.5 Evinrude with lean idle

I was able to get my motor down to idling around 750, but not well.

I had adjusted the low speed 14 turns out from the initial 1.5 with no improvement.

Now the motor is running hot. Not too much, but enough to burn me when I touch the head.

Water flow is normal.

Plugs were changed to the champion J6C from autolite 351s if I recall.

I may just need to pull the head and inspect water jackets on this one.
 
Re: !971 9.5 Evinrude with lean idle

It appears that water drips from between the intermediate exhaust cover and the inner exhaust cover.

Tried leaning the mixture from initial setting as well. The low speed adjustment does absolutely nothing.

I'm at a loss here.
 
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Re: !971 9.5 Evinrude with lean idle

First thing first. Take off the exhaust covers and see why it's leaking. You'll need new gaskets, they tear easily when you pry off the covers. A clogged passage there would cause overheating. (captian obvious) Clean out the carbon build up in there. Seal it up.

Reveiw Slow Speed Adjustment posts. Either will work. Before you turn the slow speed needle in, adjust the idle down as far as you can before it stalls, then adjust the slow speed needle. A quarter turn out after it coughs is all it takes. Give the motor time to catch up to the adjustments.
 
Re: !971 9.5 Evinrude with lean idle

I will do that, but first, I know the head gasket is bad.

I have a new one sitting on my desk here, just got to source a torque wrench so I can change it out.

I will make sure and clean stuff out while I'm changing the head gasket.

Seems like a bad head gasket may cause my troubles as well.
 
Re: !971 9.5 Evinrude with lean idle

Well, pulled the head.

Doesn't appear that any water was getting into the combustion chamber. Both cylinders are in need of a decarb.

See if I can't get some pics up.
 
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