'70s 9.9 Johnson - Fuel Intake & Gear Slippage

[PutPut1]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Hmm, I tried replying to that last night but it looks like it never went through, I'll try again.

dazk14, that's excellent advice thank you, and not too confusing.

Regarding the shift lock, it was already maxed out. Correct, the throttle is only opening a little. When I start it I turn the grip quite otherwise the throttle is completely shut and it doesn't start.

The link and sync does sound like what it needs. I can get at the two cam bolts on the starboard side, however I'm not sure how much adjustment I can get out of that. Currently, when the cam starts to turn the arrow is at least an inch from even hitting the throttle. So, how much adjustment can be provided by these bolts?

I'll try to get a picture tonight to better explain what I'm talking about because I don't think I'm doing it justice. I'll find the model # too. Thanks.

 

[dazk14]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

The cam to throttle roller position is somewhat meaningless at idle. They should not be touching.

The slow idle speed is controlled by a closed throttle and lowering timing via rotation of the mag plate far enough to slow the rpm to spec.. If you continue to lower the timing, idle speed will continue to drop and it will eventually conk out.

The idle speed knob on the port side of the motor sets the lowest idle speed, by preventing further rotation of the mag plate, although these often break and are missing.

Now onto syncing the timing and throttle take off and full throttle. You mention it seems way "out to lunch".

With the engine off. Put shifter into forward, this will allow full twist grip throttle range of motion.

Rotate twist grip throttle to maximum full throttle. Now check the split pin on the carb throttle shaft visible on stbd side...

Is the pin vertical to the motor, or within ~1/8 at top to true vertical? If it misses by a lot more, we'll have to go thru other components.

If it's reasonably close, slow the twist grip throttle until the line on the cam is centered on the roller - by eye. I know it's not touching, but within ~1/8". The can adjustment won't make up a 1/2" gap.

If you're somewhat in the hunt on the 2 items above, loosen the 2 cam hold down bolts on the mag plate and you need a thin wrench to get in there. You won't hurt anything by loosening the cam and seeing its adjustment limits.

The cam has slots and you can move it front to back and slightly side to side to get the throttle pickup mark lined up with the roller and full throttle at the other end of cam.

an alligator clip on the throttle shaft(with pin) helps to identify/magnify the throttle beginning to open.

Make sure you still have a throttle roller and not just a post.

How does the motor currently idle?

 

[PutPut1]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Well, I managed to get the throttle all figured out. Most was done by going back to the two bolts on the cam. I was surprised how much adjustment I got out of it, I thought I had it maxed out. Just made a little more difficult by all the play in old worn parts.

As far as idling, as long as I'm sure not to twist the grip too far back (because of the play) its okay. Idles a little rough but considering its age, I'm not too concerned.

Now, last issue. Fuel delivery. If it sits for a couple days or I disconnect the fuel the only way it starts is if I squirt fuel directly into a cylinder. Then it will start first pull all day. If the fuel pump runs off the vacuum in the crankcase, could low compression lead to fuel not pumping when I'm pulling the cord? I'm going to pull the carb off again but in the summer everything looked great. Also, got a spark tester and it looks a little weak but it does jump 5/16". Thoughts?

 

[racerone]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Sorry but the fuel pump has nothing to do with the " poor starting "----When you operate the manual bulb in the hose you pump fuel right through the engine fuel pump.-Now the carburetor is full.-----If choke flapper closes fully the engine starts on that supply of fuel in the bowl.--As fuel level drops then the engine fuel pump kicks in to keep the bowl full.----Make sure that the choke flapper fully closes and stays closed when you pull the cord !

 

[dazk14]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Sorry but the fuel pump has nothing to do with the " poor starting "----When you operate the manual bulb in the hose you pump fuel right through the engine fuel pump.-Now the carburetor is full.-----If choke flapper closes fully the engine starts on that supply of fuel in the bowl.--As fuel level drops then the engine fuel pump kicks in to keep the bowl full.----Make sure that the choke flapper fully closes and stays closed when you pull the cord !

Even a small amount not fully closed will torture you on a cold start! As Racerone commented above and quite a while ago.

There is a detent mechanism that is intended to hold the choke plate tight, but if you have wear, or a sloppy fit, it will allow a small gap in the choke plate and it will behave exactly as you describe.

Bear with me here, it's been quite a while on that motor... A stainless bracket with 2 tangs cradles (front/back) the plastic tang from the lower part of the choke arm/pull. Make sure no one has mistakenly rotated the plastic choke lever.

The stainless metal tangs can be squeezed tighter if you pull it apart and often will then fully hold the choke closed.

Since you mentioned you directly inject fuel... which requires you to remove air silencer screws, you may be throwing the whole mechanism off a bit. As I recall, those same screws silencer screws hold the choke knob detent in position.

Try cold starting by holding the choke knob out with one hand and pull starting with the other, while the throttle is advanced fully.

Are you now getting the throttle plate opening in neutral? Furthering that, does the engine run darn fast in full throttle neutral?

Now that I re-read the above, you may not have the air silencer off.

Another question, when you idle it "too low", does it spit back/mis-fire or just run rough and conk out?

 

[the machinist]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Another thing to consider on cold starts, is that you convey the twsit grip gear mesh appears sloppy, since the marks do not align on the handle, try to set the twist grip faster than you may think, (trying to compensate for the slop). This can overcome somewhat the slop in the gears so that the timing plate is advanced enough to start better. These motors when sloppy throttled, will start better set at a faster setting, but totally refuse to even sputter if set too slow.

 

[PutPut1]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Okay so, today I had the carb off, everything is very clean in there, fuel can flow through, no blockages in jets or otherwise.

When I was directly injecting fuel, it was into the cylinder, I took a plug out to do it, not into the carb.

I did have the air silence off and you are correct, the same screws hold the detent in place. It looks like the choke definitely closes fully and stays closed when I let go. However I haven't tried holding it shut while I try to start, I'll try that next.

Throttle problem is all fixed up and operates the way it should. I made a mark on the plastic handle so I know not to go past there when bringing to idle. (The mark is when the arrow lines up with the throttle piece on the carb). So no more problems there.

When it was idling "too low", it would just run rough then conk out. Like it was just simply idling too slow. No spitting or mis-fires.

Sometime over the next few days I'll hook the fuel up and give it a pull. I'll try putting the grip at a high throttle setting as 'the machinist' mentions

 

[dazk14]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

AS I said previously......

You have a neutral throttle limit. This can be adjusted by the shift lock on the stbd side of motor. There are 2 screws that can be loosened, then move the lock to allow more movement, then re-tighten. The concern is it may over-rev in neutral if not paying attention, but on older motors, the extra neutral throttle can help dramatically to get 'em started.

You are likely not actually opening the throttle, or very little. That will cause hard starting, especially when cold.

You need to do a link and sync.. With normal wear, The twist grip throttle will rotate, but further down the line, the wear and slop will not move adequately for starting. I am giving you a work-around for normal wear that is generally too pricey and not necessary for a serviceable rig.

I believe I made it clear that lots of neutral throttle is often needed to start these motors.

Cleaning the carb. there are 3 tiny orifices adjacent/covered by a closed throttle plate.

If those are not clean, the motor will idle poorly. If you've pulled the top welch plug and blow carb cleaner through the 3 ports, you'll see the 3 individual sprays inside the carb bore from the back side, with throttle plate somewhat rotated.

Without pulling the welch plug, and with the idle mixture needle removed, fill needle cavity with cleaner, then blow air through it and observe the rear inside throttle barrel (open throttle plate slightly, since it cover one of the holes.


At slowest idle, the cam mark will generally not line up with the cam mark. That indicates out of tune. Start with idle mixture.

to adjust mixture, Idle your motor very low(in gear is better, but not imperative), now rotate the mixture knob clockwise until the motor begins to slow down. Note - it may speed up! and then go down. When it juststarts to slow down(or spit back) make a visual note of the pointer. You may have to choke it if it conks out to get it running again.
Next rotate counterclockwise until the rpms just begin to drop(take visual note)- probably ~1/2 turn apart.
Rotate the dial to the midpoint of the 2 visual marks and you will be close.
If the motor is running faster now, slow it down and repeat.
The above can be done in a minute.
It is best to leave it a bit rich (counterclockwise), but not enough to actually change rpm noticeable...more specifically, there will be a point where rotating the adjustment say 1/8" either way tangentially make no noticeable rpm difference - go to the rich (CC) side.

 

[racerone]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Folks have been known to install the choke knob upside down.

 

[dazk14]

Re: '70s 9.9 Johnson - Fuel Intake & Gear Slippage

Folks have been known to install the choke knob upside down.

Agreed, tang side down which I indicated before. Tang facing up, screws up the slot location and prevents - or makes it darn hard to get a tight choke seal.