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1993 Mercury 9.9 Electric Choke Assembly

T

thebubba

Regular Contributor
I am trying to fine tune my new to me Mercury 9.9 motor. It doesn't seem to want to start very easily when it is cold, but once it is started it runs great all day long and restarts just fine. It has that little blue diaphram which when you pull out the manual choke it pushed the button in priming the engine. I noticed if I pull this manual choke in and out several times it eventually starts squirting fuel out the side of the diaphram housing. First is this normal? Second, the motor has an electric choke solenoid operated from the controls. When I push the key in, I can hear and see the choke solenoid engaging, but it seems like it is mounted wrong because it pushes against the carbuertor metal housing and not down on the blue diaphram buttom like I would think it should. I will try to get a picture of it tonight now I am thinking about it. I have looked in my service manual and it doesn't really give me much information on the electric choke solenoid. The manual shows it mounting in the same way mine is, but it just doesn't make any sense to me. Please help if you are familiar with this engine. galamb if you are out there, I am sure you know this engine.

Troy
 
First, when your operate the choke, whether manual or electric on this model is should result in a "shot" of gas directly into the throat of the carb.

If you pump up the bulb and make sure the fuel filter is "full", air out of the lines etc (typical after it has sit for a while), then I generally pull the choke, push it in and pull it a second time (should be well primed by then and give the shot of gas to the intake by the second pull).

When restarting warm you shouldn't need the choke unless it has been sitting for a few hours. The choke knob also does double duty as an idle speed adjustment (although it's pretty finicky/"mickey mouse") but does work after a fashion by advancing the trigger plate.

The electric choke on these is not like the enricher found on the larger horse models - it's pretty much just an "electric finger". And you are correct, it should engage the primer on the carb (or the lever that operates the primer when you pull the choke knob) depending on how it's all set up.

If you are getting gas anywhere around that primer cover (the square thingy with the stem/rod (whatever you call it) sticking out, then the diaphragm is probably shot/leaking. There is a few "pieces" under that cover (should see that in your manual) that can be replaced. The trickiest part is getting the little ball bearing to stay where it needs to be if you disassemble to check or repair.

The diaphragm kit for the primer is part of the (big) carb kit, along with the carb stuff and the fuel pump - goes for about 75 bucks - just a repair kit for the primer is 30'ish.

I may be inclined to do the entire carb - you will probably only have to do it once, so go for the "grand tour" now.
 
Thanks Graham for the informaiton. I just ordered the entire carb rebuild kit. I am certain the choke solenoid is installed wrong, maybe when I take it all apart I can make some sense out of it. I will be careful with that ball bearing you mentioned. It definitely squirts fuel out the side of the square primer housing into the engine housing. Probably a bad diaphragm then. This motor is new to me, I just tilted it down last night after testing it this weekend and a bunch of milky oil dumped out of the prop all over my driveway. I looked in the gearcase that I just had changed the oil in and it has water. I guess I will be re-sealling the lower unit as well. Looks like this one requires a special tool to get to the prop shaft seals. Any tips on changing these out?
 
It's not tough to reseal the lower unit - most often it's the oil seal(s) on the propshaft/bearing carrier and/or the big o-ring that goes around the bearing carrier.

But don't overlook a couple of new gaskets on the drain/fill plugs - would suck to tear down the case and find that it was 50 cents worth of gaskets that can be changed with a screwdriver.

The seals themselves can be picked out with a screwdriver - I reseat them with a socket and a mallet - just get them greased up/lined up and put a socket over them just big enough to catch the lip, then tap them in (poor mans bearing/seal tool).

The biggest potential hassle is getting the bearing carrier out - it "screws in" to the case - and 9 times out of 10, on a motor of this age, it's seized in there. The "special tool" for taking out the carrier kinda looks like a big socket with slots cut out of it (like a big castle nut shape). I had a buddy weld a couple of (fingers) on a breaker bar to slip in to the slots on the bearing carrier rather than pay the price Merc wants for the tool (even though I do pull a fair number of these) - you can rig something up to turn the carrier out with a bit of thinking/head scratching.

Like I said, before you get to that point it's worth pressure testing the lower unit. Some seals are far less work to get at then ones on the carrier (because of potential removal issues - I have a 15 horse "previously" salt-water run and the carrier is never going to come out - if it fails, I will replace the lower unit - it's "welded" together).

Do you have the service manual? If not, drop me an email ([email protected]) and I'll send ya the pdf section on the lower unit - will walk you through the process.
 
Thanks for the tips, I have not pressure tested the unit yet. I haven't figured out a good method to do this. I have an air compressor, what is the easiest way to do a pressure test? I would like to learn so I can do this on other units in the future. I wish it were just a 50 cent drain fill plug gasket, but they are new and look good. It definitely appears to be leaking by the prop shaft unfortunately. This is a freshwater motor, so I hope it will come apart ok. I think I can make a simple tool to remove the carrier bearing out of a pipe and a grinder to notch it. I do have the manual and if I read it correctly it is reverse thread or left hand to remove the carrier bearing. That alone is worth the price I paid for the manual. I wish the manual had a better picture and description of how the electric choke solenoid mounts and operates. I only saw one picture and a very vague description of its function. I am sure I will be asking more questions. Thank you for your wisdom and help!
 
Yes, the carrier is a (reverse) thread, so turn the opposite to "normal" when tightening/loosening.

I test my lower units, at least on the smaller motors with a compressor, garbage pail of water and the adapter from one of those cheapy gear oil changers (lower unit oil changer) that you can pick up at discount auto places for 5 bucks or so.

I have fitted the little adapter to a quick change nipple for my compressor. I drain the oil from the lower unit, hook it up to the compressor and set the pressure valve to 10 psi (more than enough) - don't over pressurize, I have blown the seals out of a lower unit for an old Eska with 15 psi (ok, they were probably bad but...)

Then submerge the whole shebang in the water and look for the origin of the bubbles.
 
I took the carburetor apart last night and found a couple of issues. Overall it was very clean inside, the fuel pump side looked good, but I will replace everything anyway. The primer button side was where all the issue are. First, the screw holding the spring and ball bearing was just about to drop out the bottom of the carb it was so loose. Inside the primer diaphram was very deteriorated. You can see through it in many places and all the debris was still inside this area. This would explain the fuel shooting out the side when you pump the primer. I still do not understand the electric choke solenoid. I cannot see any physical way for it to push the primer button. It is installed exactly the way the manual says. When it operates, it covers a small port in the side of the carb as shown in the picture. There is no information in the manual about how it functions. Does this make any sense? I will put it all back together tonight with the new parts and then start in on the lower unit.
 
Pictures of the carb Salt Lake City-20140326-02081.jpgI cannot seem to get the rest of the pictures to upload.
 
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First, when your operate the choke, whether manual or electric on this model is should result in a "shot" of gas directly into the throat of the carb.
Click to expand...
And you are correct, it should engage the primer on the carb (or the lever that operates the primer when you pull the choke knob) depending on how it's all set up.
Click to expand...
This is not correct information concerning the operation of the electric choke solenoid.
When it operates, it covers a small port in the side of the carb as shown in the picture.
Click to expand...
That is correct. The port you refer to is an air bleed into the idle circuit. The solenoid plunger is rubber tipped and seals off the air bleed resulting in the idle circuit drawing raw fuel enriching the mixture for cold start.
 
Thank you very much for the reply on how the electric choke solenoid works, That makes sense and now I will not go crazy trying to figure it out. Once I get it all back together with the bad parts replaced, I will test this electric solenoid start method out and see how effective it is. Thanks again for all the help. Tomorrow I work on the lower unit. Ugh!
 
OK, I rebuilt the carburetor this weekend, and now it seems to run perfectly. It also started right up using the manual choke. I did a pressure test on the lower unit and discovered the leak was not around the propeller shaft like I originally thought. It was clearly around the shift shaft. I put a new reseal kit in the top end of the lower unit. I just couldn't bring myself to tearing into the propeller shaft if it wasn't leaking. I have the seals if it starts in the future. Did a final test on the motor and everything is working great except it was not charging the battery. I tested the stator, it was good. Test the rectifier and it is bad. Ordered one and once it comes in I should be in great shape for the season! Thanks for all your help. I really like this forum because it is helpful and more personable than others I have tried.
 
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