Honda 9.9 only runs with choke on

[mills]

Trying to bring back to life a 1997 Honda 9.9. It is in good shape with little use. It starts right up but will only run if the choke is engaged. I took the carb off 3 x and it looks great. Just to be sure I cleaned it 2x. Same thing. Thought it might be the carb gaskets so I put some goo on them but same thing. While it was running with choke engaged I squirted water around the gaskets and nothing changed. Seems like it is getting too much air??? At a lost??? What am I missing here????

[racerone]

There are some really small holes / passage ways for fuel in these carburetors.-----Not uncommon for folks to finally get these carburetors working properly on the fourth try.-----A magnifying glass may help you.

[mills]

Thanks for the input. I will remove again and more thoroughly clean/inspect.

[jgmo]

Hi,

Yes, you likely need to go back in the carb. But do yourself a BIG favor and order a gasket set (item 1 in the link below). The fuel flow is highly dependent on those two little orings sealing perfectly. Use great care when removing and replacing them and use dielectric grease or Vaseline on them when reinstalling them.

First off, make sure the engine is actually running on both cylinders. The Honda twins will start and run on only one hole and can fool you. Do a power balance test by removing both plug boots and smearing some dielectric (tune-up) grease inside the tip of each one. Then reinstall. This makes them easy to remove and put back on during the test plus the grease helps seal out moisture.

Start the outboard and pull one plug wire using a DRY rag or thick gloves. Note the change in how it runs then do the other cylinder. If one of the cylinders isn't contributing at all then there will be no change when that plug wire is off.

When you have your carb apart, check the numbers on the main jet (item 22 in link) especially if you live at sea level. If someone set this outboard up for high altitude use it may have the wrong jet for your location. Sea level operation requires the largest size jet (102).



Make sure you pull the idle mixture screw (item 5) and hose out the idle passage forward and backward.... Meaning? ...Find the tiny hole on the top of the carburetor throat that is visible with the throttle plate closed. Put the straw tip of the cleaner can right up against it and seal it as best as you can. Flush that passage backwards and forwards like that. The idle passage MUST deliver fuel in all "modes" of operation and, thus, has to be clear. The new oring will ensure that the idle set screw is properly sealed so that it won't pull in air.

https://www.boats.net/catalog/honda/...999/carburetor

Pay particular attention to the JET SET (item 11 in the link) it feeds the passage that leads to the intermediate and high speed circuits at the top of the carburetor. The jet set has to be completely clean and also not cracked along the length of the tube. You should be able to see through the length of the tube as well as through all the drillings on the side. It has to be carefully pryed from the top of the carb throat to properly clean. The new oring will ensure proper sealing and fuel flow when carefully reinserted.

That tube feeds the passage that leads to drilled holes at the top of the carb throat that you can see when the throttle plate is held wide open. You will want to backflush each of those passages as you did with the idle orifice while you have the tube out. Spray into the hole the jet set goes to and note where the cleaner escapes. Some will come from the front of the carb through two passages located above the carb throat. Those are your high and low speed air jet feed passages. Hose them out, forward and backward, thoroughly. That's where very tiny critters take up residence.

Any time you flush a passage and see the fluid escape from more than one spot, plug one of those and then the other to get maximum cleaning. Then flush into those spots while plugging the original location and then the other escape point. This ensures thorough cleaning of these complex passages.

I'm sure I've left something out but this is a BUNCH of typing on a phone keyboard and my thumb is tired. Get back to us on what you find or questions you have about any of my rambling.

Good luck!

[mills]

JGMO,
Thanks for your incredible reply. I see why you are an outstanding contributor. Before reading your reply I took off the carb again (I think for the 5th time!!) and took another look. Again all looked fine. Butttttt I saw that part #12 had 2 holes at the top of it and that part # 22 had only 1 hole soooooo I thought maybe these holes had to line up?? So I lined them up and whalla it worked. It idles fine now. I might ad that b4 I did anything I took the carb off and apart and soaked it in gas mixed with Seafoam for a couple of days. But the carb was perfectly clean to begin with. I still have a couple of questions:
1) How do i remove the idle mixture screw? It has a tab on that limits its movement and I don't want to break it since it is unavailable. Thus, it will not screw out?
2 How does the Jet Set (#11) come out? It turns but does not unscrew. Just need to pull hard??

Again, thanks for your tremendous input. This motor is 25 years old but looks new. Very little use!!

[jgmo]

Well.. maybe you taught me something. I was unaware that the holes in the jets needed to be aligned. I will have to look into that in the carb manual.

As far as getting the jet set out, use a small pocket screwdriver to GENTLY and CAREFULLY pry it out from the top. You need to go in through the carb throat in order to engage the ledge that the oring sits on with the screwdriver tip. Engage that ledge and then give the screwdriver a gentle twist. Please don't try pulling the tube from the bottom by using pliers. That will usually damage the tube and they are no longer available.

[jgmo]

I should have said that the only thing holding the tube is the oring once the plug and emulsion tube are removed.

[mills]

Thanks again jgmo. Will do it tomorrow. Still celebrating about my successful firing up %*&*%$#@

[jgmo]

Sorry, forgot to say that the mixture screw limiter cap is glued on and you should be able to heat it with a soldering iron and lift it off. The actual screw head can then be accessed.

But...
You make a good point about both the screw being no longer available. Along with several other components including the jet set tube. If your outboard now runs the way you want it might be wisest to not disturb either and leave well enough alone.

[mills]

Jgmo,
Thanks for your input again. Started it up again this morning, adjusted the idle and mixture screw and it runs PERFECT. Thus, if it ain't broke don't fix it. Just have to get a thermostat and gasket for it. The previous owner took it out because it was overheating because the water inlet tube was stopped up with the old impeller that he destroyed when he ran it dry.

[jgmo]

Yep! Owners like that give Honda a bad rap.
Glad you're up and at 'em!
Have fun with her....uh...she...uh...it...uh...you know!....
...the THANG!

[racerone]

Run carburetor dry each time you are done fishing.-----Empty carburetors do not plug up !!!

[jgmo]

Amen to that racerone!