cannot remove my old 1982 Johnson 90 hp v4 carburetor - got stuck - need help

[ib18]

Last Friday, I was preparing for my ocean fishing so starting the boat Johnson 90 hp up. I had no trouble starting it up, but had trouble keep it running unless I keep the throttle higher than normal idle speed. So, I opened the motor cover and discovered fuel was dripping out of the front carb intake. I was surprised, so I researched it online and found people saying probably a stuck carb float or worn out fuel float somewhere. Today, I decided to remove the carb from my motor. Bummer, I got stuck because the studs from the engine block were too long. I was not able to remove the nuts without stripping them. So, do I just use a dremmel saw to grind or cut the studs shorter so I can remove the carb? or what? is this normal to you. 1982 Johnson 90hp v4. J90MLCNB is the serial number.

Thanks.

 

[interalian]

No. You loosen each nut as far as you can, then tap the carb to release the intake/carb gasket. Then loosen further until you can remove it. No need to cut anything.

Oh, and you have two carbs. They'll need to be link/sync once you put them back on too.

 

[ib18]

No Title

The nut was stuck by the nipple on the carb body, I don't want to use force to take the nut out fearing stripping the stud.

 

[ib18]

No. You loosen each nut as far as you can, then tap the carb to release the intake/carb gasket. Then loosen further until you can remove it. No need to cut anything.

Oh, and you have two carbs. They'll need to be link/sync once you put them back on too.

Wow, thanks for the super fast reply! I will try that when I have time to do it.

 

[ib18]

here is a video of my outboard dripping gasoline from the carburetor air intake. The gasoline is flowing down to the outboard motor cowl pan and if it touches my electric wire sparks, then boom! my outboard will be exploded like a bomb on my boat. Me and my guests may never boat again! So, first thing first, tear it down to fix the leaky carb.

 

[oldboat1]

Float valve issue, maybe? Carb nuts come off as Interalian describes. (Try not to drop it down in the pan!)

 

[Fed]

The air box cover should have a gasket that stops it leaking and there's a hole in the air box on the bottom Port side that should have a hose on the back to recirculate any leaked fuel back into the crankcase.

 

[ib18]

The air box cover should have a gasket that stops it leaking and there's a hole in the air box on the bottom Port side that should have a hose on the back to recirculate any leaked fuel back into the crankcase.

ok, thanks. I will take a look this weekend. Gasket probably broke long time ago, didn't see one. if any I simply missed it. didn't see the hose on the port side either this is a 1982 Johnson 90 hp MLCNB90 is the model.

 

[ib18]

a silly question - how many carb repair kit should I buy? I think 2 but not sure because there are 4 carbs and 2 attached together for top and 2 for bottom

 

[interalian]

Your motor has two carbs, each has two throats. One throat feeds one cylinder. You need two carb kits. BRP ones are best.

 

[ib18]

Float valve issue, maybe? Carb nuts come off as Interalian describes. (Try not to drop it down in the pan!)

Hmm, maybe float issue? can you elaborate? This started end of last year as I discovered leak down to my mid section on the starboard (right) side after I ran the motor in the river. I thought it was unburned 2 cycle oil left in the carb and eventually leak down to the mid section. It got more serious this past weekend. It started dripping even when I ran the engine. so, took it down to see whether float was bad. What else could be there?

 

[interalian]

OK, here's the test. Remove the passel of bolts holding the plastic cover on the silencer. Run engine. Look for fuel dribbling or gushing out of the hole just above, and between the carbs on the front of the aluminum silencer housing. If no fuel is coming out, your float (needle) valves are probably fine. With the motor running, hold a business card about an inch in front of each throat. You should get a fine mist of fuel on the card - normal. The mist will normally condense on the silencer cover and run down to a drain hose at the bottom. If the gasket is farked you'll get fuel leaking into the motor pan. This excess fuel drains through a rubber hose to a fitting at the bottom of the crankcase, under the lower carb.

 

[ib18]

OK, here's the test. Remove the passel of bolts holding the plastic cover on the silencer. Run engine. Look for fuel dribbling or gushing out of the hole just above, and between the carbs on the front of the aluminum silencer housing. If no fuel is coming out, your float (needle) valves are probably fine. With the motor running, hold a business card about an inch in front of each throat. You should get a fine mist of fuel on the card - normal. The mist will normally condense on the silencer cover and run down to a drain hose at the bottom. If the gasket is farked you'll get fuel leaking into the motor pan. This excess fuel drains through a rubber hose to a fitting at the bottom of the crankcase, under the lower carb.

Wow, thx for your detailed instructions. I will take a look of my video again. Don't think I recorded with the silencer cover off. In the process of rebuilding the carbs now. I will know for sure if 1 of the needles and float got stuck or sticky when I tear into the float this weekend. Need to get this motor back on the water so I can catch the last bit of fishing season. I have been opened up the silencer in the last 2 years to spray starting fluid bcz I am still not familiar with the choke and my motor starting cold. Now, I know (1) electric choke it 5-10 times (2) squuze the fuel primer bulb until firm (3) push the throttle level to high (forward) by lifting the lever on the remote control,(4) press in and hold the key for a few seconds to crank the motor. Generally my motor will start in less than 5 tries. If the lever is not raised then it may take more than 10 times to start the motor. I then would open the silencer cover and spray starting fluid or carb cleaner into carb air intake. Motor would start in less than 5 cranks. I guess silencer gasket fell away without me noticing it

 

[ib18]

No Title

Fuel is leaking from the center big hole between top and bottom carb. See pic

 

[ib18]

I think my float or needle is bad - fuel is leaking from the center hole - see video

 

[ib18]

just rebuilt the fuel pump with the repair kit and cleaning the 2 crabs this weekend.

Is 0321722 the right air silencer gasket for my Johnson 90 hp v4? J90MLCNB model.

I think so but just want somebody to confirm it. Thanks.

 

[Fed]

That's the right gasket, did you find the nipple in the back of the air box with the hose running off to the crankcase?

Any leakage from the carbies after the rebuild?

BTW, they tend to let a little gas out when you tilt the motor & the float bowls are full, this is normal & gets caught by the air box.

 

[ib18]

No Title

I opened the carbs, and they are very clean. No wonder I had no trouble starting my motor. I have been running sea foam mix with my oil and gas mix, so that may be part of it. The carb gaskets look fairly new (prior owner rebuilt it just before I bought his motor from him - a crab fisherman), so I decided not to bother buying new ones. The needles and floats looked and worked perfectly. I have not had a chance to run it. Waiting for the air silencer gasket to come, so I will run it next weekend.
Yes and thanks, I did find the right nipple and the fuel tube running from it back to the engine cylinders.

The previous owner must have installed a 115hp carb onto my Johnson 90 hp v4 outboard. The bottom carb has this tag on 1 of the screws. Maybe my Johnson 90 is effectively a Johnson 115. Oh my goodness - Nice! Good surprise. Do you agree thats what the tag in the picture is showing?

 

[oldboat1]

Try another tank with 50:1 and no Seafoam. Mix may be too rich.

 

[ib18]

Try another tank with 50:1 and no Seafoam. Mix may be too rich.

good suggestion. I didn't have the problem of leaking before I started mixing seafoam.

2 more questions though - I found the tag with 393173 attached to my Bottom carb instead of being at the top like what I found on eBay selling for 115hp Johnson outboard as 393173 at the top.

(1) Does it matter that I have a 90 carb on top, and 115 carb at the bottom?
(2) Does it matter whether 393173 is on top or at the bottom for my motor?

393173 - Top
393174 - Bottom