cleaning carburators on small engines

[Bob Condon]

Ok, so I have a Tohatsu 5 hp M5B engine (1993).

The engine came with the boat and has been less than pleasing.

I have had the carburator rebuilt 2 times this spring. They also were suppose to
fix the lack of cooling water coming through the engine.


When I got the engine back a few weeks ago, I did not run it. When I started last weekend,
there was no power in gear (it would stall) and no cooling water was coming through.
I fixed the cooling water by pulling the drain plug, and blew are back through the pump and a piece of greesy
glob came out. I also blew through the drain plub back through the strainer at the bottom of the
engine...

Started the engine and ViewaLaaaaaaa, a steady stream of water.

But the carb was still messed up and finally, it would not start.

====

Took it back, with temper under control, told him that his rebuild seems to not work. He started it
and it ran like crap in his tank.

SO he charged me to rebuild it AGAIN and said there was crap in the carb... I asked him about this
and waved his hands, did a dance, and tried to bullsh*t me..

SO I looked on the Internet but there was only one site that had a picture of "a generic carb" and then
a description of how to rebuild. The only issue is that all the terms used in the writeup did not match the picture...
I swear it is a conspiracy. 

I am very handy (built boats and houses) and grew up with a machinist as a Dad!

I expect Skip will have the best answer, but where can I find good information.

SO far the best information I heard was from one of the 17 year olds in the shop was
to run the bowl as dry as you can. If you are not going to run the engine for a couple of weeks,
pull the drain plug in the bowl. let it drain and spray WD40 into the bowl which will coat the jets and everything
with products that never go bad... He also said to use 93 octane because octane decreases over the summer
and to use the Marine Stabil product.

How do I clean and rebuild a carb when it goes bad and save myself $50 each time.... and hassle..

Damn Ethinol gas

I am told that there are stations in New Hampshire for Marine that does not have this gas additive?

many thanks! 

[Bob23]

Bob:
   I have been using premium fuel in my outboard (1988 Nissan , chainsaw, generator, powerwasher...you get the picture. I also buy the best 2 stroke oil I can find and add a dash of Stabil. I've had my boat (1985 23/2) and motor for 5 years...never had a problem. I do run it dry in the fall and never use gas left over from the previous year. The local hazardous waste recyclers are happy to take it off my hand. Cheapest insurance I can think of.
   Sounds like you need to find a new and competent mechanic. And get a shop manual for that particular motor. I had a Tohatsu 3.5 and was very happy. BTW, Tohatsu and Nissan are basically the same. Hope this helps..
Bob23

[Bob Condon]

Thanks Bob

I have not been very happy with the mechanic. There are very few folks im Mass because
there is not that many lakes. If I went to New Hampshire, he number of folks is more
plentiful. In Maine, there are a few but there is "local" pricing which is reasonable and then
there is "Mass or Out-Of-state" pricing which is typically cheaper to buy a new motor.

I think I am on the good side of the world now because the motor ran in a bucket very well
today so next weekend I hope to splash the CP19 for the summer and then she will be a
happy boat. She sits on the hard looking at the boat ramp and has a nasty scowl on her bow.

In my Cape Dory, I always shine the internal tank (pull the old fuel, get the bits of mold that grow in diesel out
and put in fresh fuel to get a happy engine!)

Bob

[Billy]

yea I'm in the same boat. rebuilt carb 4 times on a 2004 2.5 horse Yamaha. Last I heard was to add the stabilizer, and that the ethonol (sp?) was eating the fuel line. I replaced it and we'll see. Check your fuel line. It may be coroded.

[Craig Weis]

Yep ethanol and tiny tiny jets don't play well together. I fuel up and have good luck with BP Premium, for now no ethanol in that.
My two cycle 5 hp Mercury plugs up with a green sticky jello sludge on all other fuels tried.

You will need in your boat's tool box;
~One small flat blade screw driver that is capable of holding onto the screw.
~A larger and long screw driver to disassemble the carb.
~A small needle nose for those spring clamps on the fuel and vent lines.
~A clean white dish size towel to lay out all the pieces.
~A can of carb cleaner that WILL NOT em brittle plastic parts. I think that's non-clorinated.
~A can of WD-40.
~A small MAG flashlight with fresh AA batteries.
~1/8" drive & rat-shit with a two inch extention and socket for the nut holding carb to the flapper valve assembly. 13mm?
~The patients of Jobe.
~A small magnate on the end of a flexible spring and screw driver handle.
~Round wooden tapered tooth picks.
~Pencil and paper for notes and sketches.

After three cleanings, and that be a carburetor tear down, both at dock side, on the water while adrift and in the garage bench with bright light and comfortable chair I carefully picked out that green blob from the main metering jet with a tapered wooden toothpick. Do not use any thing harder then the brass jet or it may be enlarged or scratched. You don't want this orifice scratched.

Every paper gasket if handled with care can be used again. IT IS IMPORTANT to note or jot down the front side and top or bottom of all gaskets and componets taken apart in your notes so you can put it back together just a nice as the zipperhead that put it together in the first place. Additionally a small tube of non-hardening Permatex, just in case.

I carry a spare spark plug and I did away with that stupid check valve in the fuel system designed to segregate the internal tank from the feed to the external fuel tank. That thing actually wheezed at me when I tried to pull start the engine while it slowly buzzed back to atmospheric air pressure. Who needs it? Out with it. It just stops the flow of fuel into a hose that dead ends at a fuel tank selector.

What you'll usually find is the very thin rubber flat bladders that pause back and forth with the two cycle crank shaft pressure and are designed to move fuel to the internal porting in the carb are fagged out to a point where they don't do much. But you can't leave them out because they cover certain orifice's used in the valving of the carb/air/fuel.

There is really nothing hard about this but a need to be alert and careful is necessary. If it's a hole you need to see into or through it. If it's a surface like the inside of a fuel bowel it should be clean just like the factory sent it out. If something looks like it should not be there, it probably needs to be removed.
Figure an hour and a half to R&R, and clean the carb. Don't loose nothing over the side.

skip.

[CaptRon28]

You can't really leave enthanol blended fuel in your tank or motor for more than a month or two. Older motors made before ethanol was forced upon us suffer even more. Some of the newer gas stabilizers formulated for ethanol help, but it's best to drain the gas tank and run it dry if you don't plan on using the boat for several weeks. Running it dry is somewhat better than draining the carburetor, but even that's better than leaving the fuel in the motor. Note that non-ethanol gas is available in most states and it's worth the extra cost if there is a station nearby that has it. Premium fuel won't make a difference.

If the ethanol industry gets it way, we'll all be choking on 15 and 20 percent ethanol in the future, with higher percentages to follow.

[Salty19]

Hey there, Bob.

I guess I can't say I feel your pain but certainly have had dirty carbs in the past.  After owning many dirt bikes and carburated toys,  there is a similiarity among carbs.  Once you clean one, you can do another one-for the most part.

In the case of outboards, the hardest part is to get them off and back on without loosing anything.

Here's my advice, worth $.02

Remove the carb.  You'll encounter the fuel line, the air line, the throttle assembly and choke.  On my old Johnson 2 stroke and now 6hp nissan 4 stroke (Tohatsu), these were easy to remove the odds and ends from the carb.  Take a picture once you lift the cover to document how things fit (they really are not that bad) if you want to.  The one tricky thing if it's there is an adjustable pipe or rod that moves when you throttle up.  This is the ignition timing advance.  This is the one piece that you need to get back on correctly!  Some carbs have them integrated with the throttle in a way that you don't have to mess with them.  Some do not.  If it's not the throttle of choke, it's probably this mechanism.  Get it back exactly as you found it (use tape to mark the rod with).

Once you have the carb removed--typically two long bolts that go through the entire intake, carb and engine manifold, remove the top plate of the carb if has one. Now remove the bottom cover, called a float bowl.  Trick: Slightly loosen each screw BEFORE you unscrew them very far. Otherwise the last one or two screws will be a pain, and you'll probably strip the threads.  Don't ask me how I know this. Also use a good screwdriver with good bite to it.  These are not easy to get out if you strip them.

OK, now be gentle.  You'll see the float underneath, generally white in color and it moves around a bit.  Be delicate here.  Do not upset it too much. Do not lay the carb down on this.

Now put your nitrile gloves and goggles on and blast away with carb cleaner.  If you do see green or brown gunk when removing the lower bowl cover, you're in for more cleaning.  Spray everywhere and put the nozzle down any holes you see. BLAST AWAY! Do this outside and away from your cars, kids, etc, carb cleaner is pretty strong.

"Gunk" brand sells gallon size dunking containers. Dunk your carb in the cleaner with the covers off overnight.   Before you dunk it, remove the float bowl Oring. I have to say, I will always be using the dunk method, there are so many areas you just can't get to from the outside.

Then spray it again with carb cleaner the next day.  On the bottom if you see any brass pieces that allow you to unscrew them, do so and blast the hole with more carb cleaner.  Better yet, undo these before you dunk it. Keep any parts that you remove safe from getting lost. Note:  DO NOT MESS WITH any brass screws on the sides or top of the carb.  If a screw has a spring behind it, do not touch these either (these are generally idle and what's called a pilot air screw wihich regulates air flow at low engine speeds.

Once all is sprayed down, blast compressed air through EVERY orifice that you see. Depending how complex the carb is, there will be betwen 4 and 9 holes to blast.  

Now reassemble the carb.  Now here's where I don't agree with skip..gaskets are one time use items. Otherwise you'll get an airleak, which WILL make the engine run badly. They are normally very inexpensive (but you have to be prepared).

Note a few things while you're there.   Does the float seem like it has fluid in it?  If so, it's toast..replace it.  Is there any visible dirt inside? If so, this is not actually dirt, it's dried fuel solids. These only form when gas has been sitting there awhile. This is an indication that you should probably dunk the carb first and foremost, secondly a sign that you didn't prepare it properly.

As for preventing things, I filter the gas prior to putting in the tank, use 93 octane, use seafoam and use marine grade stabil. If the engine will be sitting for a few weeks, drain the gas from the carb.  That is the one at the bottom of the float bowl you removed.   Even better, turn the gas off or unplug the gas line (if external tank) and run the engine on high speed until it stalls.  For winterizing, I generally pull the carb and clean it as above. That way nothing gets gummed up and it's ready for the next season.  

Just cleaned a friends Yamaha 4 stroke 9.9.  Didn't winterize it at all (due to injury).  It was pretty nasty after 7 months of fuel sitting there.  Engine would not start at all.  Now it purrs like a kitty following this method.

Capt Ron is spot on too.  Only dispense the required fuel for about 2-3 weeks.  Anything older than this could gum it up.

Funny how I never had problems with things like lawnmowers, weedwackers, chainsaws...all work oriented things.  But the toys have problems! I must not be going to church often enough!

[CaptRon28]

Salty -

You're right - carburetor cleaner, gloves, dunking, spraying into the tiny jets and using compressed air to blow everything out afterwards is the best (and maybe only) way to do it. But I still think that you don't have to do this that often if you're very carefull about not leaving fuel in the motor and tank. Before ethanol you could probably get away with several months of storage (especially if you stabilize it), but the addition of E10 has thrown that out the window. I think a month is about as long as you'd want this _____ (use your own word) to sit in the carburetor, fuel line and tank. The carb is more of a problem because the tiny passages get gummed up very easily.

The larger cans I keep home to hold the stuff (hopefully non-ethanol when and where available) are filtered before they go into the boat's gas tank. You can buy these funnel like filters at many stores, including West Marine. They remove water as well. I've got two 6 gallon cans and a 5 gallon can - the first pair hold non-filtered fuel, the 5 gallon can filtered. The boats only get filled from the filtered can and that gets filtered again as it's poured in. I also inslalled a Raycor inline fuel filter / water separator on the Honda 20hp powered Telstar. The Mercury EFI 250hp SeaDoo jet boat already has one. Any gas that's not used up in about 6 weeks gets dumped into the truck and it's gone pretty soon. The Horizon has the Yanmar and hopefully I'll be able to avoid some of this. The lawnmowers, weed wackers, snowblowers probably don't suffer the same fate because the fuel gets used up fairly quickly.

[Salty19]

Ron- Your advice is very good here.  Fresh fuel and timely removal of old fuel is the best way to prevent problems for occuring in the first place.

[HideAway]

hey thanks for the tip about the fuel hose.   I ve been having a terrible time with Mr E.   He 'll run fine in all conditions then suddenly accelerate or slow.  I've cleaned the carb - it was dirty - new plugs checked all the electrical etc.  But that hose is very old --- hmmmm

The other thing I've done is switch back to a three gallon tank. - that gives me three hours of run time - enough for day sailing or a trip  to the Gulf.  I can use the six when we go on long trips.

Don t believe I'll be buying anything from BP

Matt

[Shawn]

You might also consider installing a filter like the Racor 120R-RAC-01 which will also remove water from the gas.

On my 23/3 I was able to fit the filter under the tank cover with my 3 gallon tank next to it.

Shawn

[Gil Weiss]

I have had a bunch of carb problems due to ethanol in the gas. Rebuilds, cleaning, etc. did not really work. Had a new carb put on my 6HP 4stroke Merc (Tohatsu) last week and it runs like new.

The ethanol problems are a real PIA!!! I use Valve-Tech fuel additive now instead of green Stab-Bil. I also run out the carb evrytime I use the motor. We shall see . . .

BTW, I am not sure about British Pollution (BP) premium not having any ethanol.

[Bob Condon]

I splashed the boat for the season.

I was able to splash alone this year but here was a fellow who offered to push the boat off the trailer if
needed.

The engine worked like a champ.

It started on the first pull.

Changes I made is using 93 octane fuel + Marine stabil in the gas
I need to order the switch because t is flakey... disconnected it from the
ground and shut motor down by either running out the gas or stalling
her out at low throttle

WIll sail in 2 weeks to see how the motor does then.. I expect it to be fine!


She is once again a happy boat on the mooring and not on the trailer!
Bob

[Craig Weis]

O/B owner's manual says this:

The problem is --> "Deterioration of ELASTOMERS and Plastic parts."

Yep this alone fags out the bellows that react to the two cycle engine pulsations that drive the vacuum operated fuel pump that delivers fuel to the carb...and soon your adrift.

skip.

[skip1930]

Once again British Petroleum [BP] provides alcohol free fuel in there Premium Grade Gasoline.

Don't be cheap when buying such a small amount of seasonal boat gas.
Save's the rubbers in the carbs.

Enjoy the immersing boating season.

skip.