Quick carb cleanng tips for 1968 100hp Evinrude?

[autoarcheologist]

I am getting ready to get our 68 Evinrude 100hp started this spring and wondering if anybody has any tips for a quick carb cleaning without removing the carb for a full clean?

The carb on the 68 100hp is a "series 2" I believe, which is basically four single bore carbs. It's relatively rare, which means a rebuild kit is over $200.

I am hoping to do a quick clean first, shoot out any gunk with spray cleaner, drain the lines, fill with fresh gas and see if it will start and run.

BACKGROUND:

At the end of 2014 the boat died while launching and wouldn't restart. I traced the problem to a bad ignition module, sent it back under warranty, and got a new one in the spring of 2015. That winter I drained and winterized the carbs and stabilized the gas in the tank.

In 2015 I couldn't get the motor to start, had a super busy summer, and never got much time to diagnose it further. I do know the module is giving me spark, the battery is new and good, but it wouldn't fire.

I'm thinking the gas that was left over the winter is going off, and now unfortunately it has been in the tank for over a year, and I was so frustrated with the boat I never winterized the motor properly last fall. So whatever gas was in the carbs has probably evaporated and left a mess.

So I probably need to pull the carbs, disassemble and clean them, and reassemble with new gaskets and seals. Hopefully the floats and needle valves are good and can be reused as they are incredibly pricey on this carb.

But I was wondering if anybody had any tricks to try before I dig into the carb. I have never rebuild one, so I'm a little gun shy about screwing it up.

Also, it ran great at high speed, but didn't like to start and had a rough idle. So it probably needs some idle adjustments after a good clean.

I really hope to have the boat on the water again this summer.

Thanks!
Ian
1968 Evinrude 100hp
1968 Reinell 18'.

 

[ondarvr]

While it's always a good idea to use a rebuild kit, I rarely do, just pull them apart and clean them, if you destroy a gasket get one kit.

 

[GA_Boater]

There is not such thing as an on the motor quick clean. If the carbs need cleaned, they need to be removed, soaked in carb cleaner and blown out with air, It just can't be done without removal. Sorry.

 

[Willyclay]

I have a 1968 Johnson 100HP and, IMHO, suggest you do a little more troubleshooting before you start pulling that carb off/apart. Since you repaired the ignition system and think it is okay, try cranking the motor over while spraying pre-mix fuel directly into the carb throats. If that fires then you have confirmed the carb/fuel delivery problem. If no firing, then your ignition system still has a problem. These motors with the first-generation OMC electronic ignition require a fully charged battery to start or else component damage may occur. Good luck!

 

[F_R]

I suggest you pull the drain plugs to see if there is gunk/varnish on the inner end or in the jets. If they are clean, do not take that carburetor apart unless it is flooding or something. If you do have to go into it, 90% of the time the float bowls removal is as far as you need to go. Unfortunately, that is the toughest part. You will need new gaskets, and they are quite complex and difficult to make yourself. You need a special tool to set the float heights, or a not-so-easy measurement system otherwise.

 

[racerone]

I agree with post # 5 ----Most times " carburetor problems " turn out to be something else.

 

[tblshur]

aa there are some good info at top of this page in sticky post by tashasdaddy. hope this helps good luck:joyous:

 

[autoarcheologist]

I suggest you pull the drain plugs to see if there is gunk/varnish on the inner end or in the jets. If they are clean, do not take that carburetor apart unless it is flooding or something. If you do have to go into it, 90% of the time the float bowls removal is as far as you need to go. Unfortunately, that is the toughest part. You will need new gaskets, and they are quite complex and difficult to make yourself. You need a special tool to set the float heights, or a not-so-easy measurement system otherwise.

Thanks everybody, I'm really hoping I don't have to pull the carbs.

Can you elaborate on how to check the jets? I did pull the drain plugs and there was still fuel in each bowl, so it hadn't all evaporated. It's looking pretty green, I"m thinking enough might have evaporated that it's got too much oil in the mix now, but again this is my first 2 stroke boat motor.

 

[autoarcheologist]

I have a 1968 Johnson 100HP and, IMHO, suggest you do a little more troubleshooting before you start pulling that carb off/apart. Since you repaired the ignition system and think it is okay, try cranking the motor over while spraying pre-mix fuel directly into the carb throats. If that fires then you have confirmed the carb/fuel delivery problem. If no firing, then your ignition system still has a problem. These motors with the first-generation OMC electronic ignition require a fully charged battery to start or else component damage may occur. Good luck!

How do you spray pre-mix into the throats?

 

[racerone]

There is a special screwdriver to remove the jets.-------A 3/16" shank screwdriver may get them out.------Or you could modify a 3/16" diameter screwdriver to look like the factory one.

 

[F_R]

No Title

The special screwdriver has parallel sides on the blade. Attempting to get them out with a makeshift screwdriver might work if you are lucky, and it might spread the soft brass jet, making it even harder to get out --or impossible. Feeling lucky??

 

[Willyclay]

How do you spray pre-mix into the throats?

Before I respond to your question, I want to emphasize the excellent advice you are getting from some of the forum gurus which I am not. F_R's comment about the special tool for setting the float levels is a really big deal. That said, you will need to remove the "shield" that covers the carb openings and squirt premix made with fresh gas directly into each carb throat with a spray bottle, turkey baster, syringe, etc. A few ounces is all you need so the cylinders do not flood. If it does not run, I would start my detective work with the fuel pump by disconnecting the supply line from the pump to the carb inlet and crank the motor. Fuel flowing out the hose will be a good indication that the pump is supplying the carb with fuel and is not the problem. Good luck!

 

[Chrisravosa36]

You can try seafoam, it is safe to use, and it worked with my motor, but your motor has to be started for this to work.

 

[glust]

Is this a 2 stroke motor? I am not sure but if it is be careful starting/running on ether or starting fluid. That motor needs oil to run properly. If you use straight starting fluid you will not only wash down the walls of the cylinder, but the crank bearings as well. Starting fluid is a solvent for oil. Remember grabbing a can to wash your hands or to de-gunk a motor??? Good luck with your project

 

[Chrisravosa36]

Is this a 2 stroke motor? I am not sure but if it is be careful starting/running on ether or starting fluid.

Hes totally right, I usally fix my starting fluid with at least 4oz of oil per a can, I will spray it all out into a windex containor, add about 4oz of oil, and start it. Id do the same with seafoam.

 

[ondarvr]

While not a great product to user in general, there are plenty of starter fluids with oil already in the mix.

 

[oldboat1]

^^GUNK makes one, probably many others.

Interesting posts: I'm not sure about mixing ether and oil in a Windex bottle, or what happens when you use starter fluid to clean your hands or an engine -- cold engine, presumably -- but an occasional mist of starter fluid at the carb throat won't kill an outboard (keeping in mind safety issues, as the stuff is......explosive).

Having said that, there's probably a youTube out there showing a guy emptying a can of starter fluid into an old outboard, or running wide open on muffs. Don't think either of those things is real smart.

In the OP's case, I think I would try to spray some carb cleaner into h.s. and l.s. jets without removing that carb. And after using carb cleaner, think that might be a situation for starter fluid -- might be tempted to use some to get it to pop, hopefully to catch and run on some fresh mix. If there is a built in tank, there might be quite a bit of old fuel to dispose of, potentially -- think I might check it for water first (take a sample, and let it settle out). It still might be usable -- but probably a good idea to run on a separate tank initially with fresh fuel, just to get it up and running.

 

[Chrisravosa36]

^^GUNK makes one, probably many others.

Interesting posts: I'm not sure about mixing ether and oil in a Windex bottle, or what happens when you use starter fluid to clean your hands or an engine -- cold engine, presumably

Its worked well for me in the past, but again you cant use to much of it, its just a saftey thing.