Modern Outboard Repair - carburetors

[Gunni]

Learned an important lesson this season about the nature of maintaining the modern carbureted outboard. You know, the small kickers like my Tohatsu 9.8 hp. Don't bother trying to rebuild the carburetor, replace it.

After two rebuilds attempting to return easy starting and slow idle, spending nearly $100 on rebuild kits, I called my local outboard repair guy and asked what I was doing wrong. I' ve rebuilt many carburetors, tricked out carburetors to improve performance and know my way around these things. No amount of stripping down, soaking, brushing or cleaning could return my 6 year old carburetor to running condition. I was beginning to believe my engine had other problems. Finally repairman said, "you know, frankly I don't attempt to rebuild them any more, I replace them". So I bit the bullet and ordered up a new $170 tohatsu carb and bolted it on. Instant return to OEM performance! I kept the old one for another try at getting it back to original, but I don't have much confidence. The combination of extremely small passages, and the corrosive effects of ethanol/water contaminants make rebuilding carbs a thing of the past. They are now disposable. Hopefully I can get another 6 years out of this one. I have also become a fanatic about gas treatments, gas storage, and fuel system purges.

 

[Stu Jackson]

Great points, Gunni. When I was down cleaning up our boat (New Years Resolution 101!!! ), I found the replacement carb I bought a few years ago. NOW I finally know where it's been hiding from me.

 

[Gunni]

Even after buying a new carburetor, I did another tear-down and cleaning on my old one, convinced that I could get it working. Hard to believe they don't build them for repair.

 

[thinwater]

I suspect the problem might be the lack of good anti-corrosion additive. Though spray cleaners are effective on varnish, they can't dissolve metal corrosion products. It isn't that they don't build them for repair, it just takes specific focus on the jets (you don't need the "kit," you just need to get the passages clean--I've rebuilt may recent small carbs.). With a good additive, corrosion should be zero.

I've done a bunch of testing for mags (in order of preference):

* Biobor EB
* Seafoam
* Merc Stor-n-start
* Valvtect Ethanol
* Startron

There are some better-advertised products out there, but these are the ones that actually worked, time after time. They really do help, particularly on kickers.

 

[gettinthere]

2 stroke or 4 stroke? I had the Tohatsu 9.8 2 stroke and did a rebuild kit with excellent results. I added a fuel filter to the dink transom to keep the water and gunk out as well. It ran very well.

 

[Gunni]

4-Stroke, with the latest lean-run features to make them burn clean. I'm going after the fuel "pitot" tube holes next, they were always a problem with the Keihin flat-slide carbs. My british Amal's never had this problem. However they were not very fuel efficient.

And thanks Thinwater, I have read, and re-read your fuel additive testing, some of the best stuff Practical-Sailor does! I have been using corrosion additives for years. Changed from Startron to SeaFoam after latest testing. Your sleuthing on moisture control in marine gasoline fuel storage was my ah-ha moment. The stuff has all that ethanol in there looking to suck up water. And fact is I have a hard time using up gasoline fuel, this outboard burns so little, so now I dump it in the truck after a month and buy fresh.

 

[KD3PC]

ultrasonic cleaner is the only way to get these carbs and their fine passages clean. some John deere dealers will do them for a flat rate...

 

[uncledom]

ultrasonic cleaner is the only way to get these carbs and their fine passages clean. some John deere dealers will do them for a flat rate...

Totally agree with chemical bath or sonic cleaning. You just can not seem to get the small passages clean with just a spray cleaner. I have given up on dinghy motor maintenance and have switched to propane.

 

[gettinthere]

I think its telling that I had no issues in maintaining the fuel system on my 2 stroke 9.8 vs the big problems apparent with the 4 stroke. I hear this a lot. We decided to upgrade to 15hp while in the Bahamas. The yamaha 15 sells out the day they get them. You have to be on a 6 week wait list with a deposit made to get one. We have had many comments that people thought it was a 4 stroke, because it is as quiet as a 4. More efficient than older 2 strokes and 100:1 mix too.

 

[druid]

Carburetors and ignitions are why I switched to fixing diesel engines

druid

 

[Gunni]

Amarc 9.25 hp Diesel outboard, 135 lbs.

 

[uncledom]

Do you bench press that Gunni? Seems a shame for all that weight to have only one purpose

 

[Maine Sail]

I have pretty much solved all my small engine carburetor issues....

With my leaf blower, weed whacker, EU2000 generator & chain saw I always run TruFuel either regular or the 50:1 premix.

With my snowblower, lawnmower, outboards etc. I run TruFuel through for the last 3-4 hours of run time before storage.

Since I began using TruFuel (or similar) zero issues. Since e-10 ethanol came to Maine I was buying a new carb, or two, at least yearly, I no longer do.

Our local fire department is also using it and all fuel related issues with pumps etc. have gone away. Not inexpensive but less than a new carb or rebuild or hours spent fiddling with the engine.

 

[Gunni]

Yeah, I've been running tru-fuel mix gasoline for a few years in my yard equipment and Stihl Farmboss with great results. Notice that they are now selling in 5 gallon fuel cans. Made the switch to a propane generator a few years ago, after experimenting with a conversion from US Carburetor over in West Virginia. Just took my old gasoline genset to recycling.

 

[Gunni]

Do you bench press that Gunni? Seems a shame for all that weight to have only one purpose

No, strap it to my back for PT runs

 

[Mark Maulden]

Never heard of Trufuel..who sells it? Ethanol free seems to work for me.

 

[Alan Gomes]

How long can TruFuel be stored? I have an outboard that I use at sometimes irregular/infrequent intervals and am wondering about whether this stuff has a certain shelf life.

 

[Mark Maulden]

Ok i googled it..Home Depot has it and i would guess some others. Have never seen it on the shelves...$24.00/gal...i guess that would offset the cost of carbs. Most marinas around here have ethanol free gas. Not sure what octane, but im still using some i got two yrs ago with good results. (Along with Sta-bil) .I do run engines several times/yr at minimum...

 

[Ward H]

I have been using AV gas for a couple of seasons in my Yamaha 9.9 4 stroke since ethanol free gas is not sold in NJ.
Does TruFuel have any advantage over AV gas?
Does AV gas or an OB using AV gas, benefit from any type of fuel additive since ethanol is not problem?

Thanks

 

[Sefuller]

I have pretty much solved all my small engine carburetor issues....

With my leaf blower, weed whacker, EU2000 generator & chain saw I always run TruFuel either regular or the 50:1 premix.

With my snowblower, lawnmower, outboards etc. I run TruFuel through for the last 3-4 hours of run time before storage.

I was very interested in this, however I can't find anything that says TruFuel is ok for 2 cycle outboards, in fact everything on their site says air-cooled. I have a 1970 Johnson 1.5 hp on our dinghy that we use to get to the mooring. The motor sits on the under the dinghy on a dock during the week and we typically use it on weekends. With our regular E-10 gas and SeaFoam, the gas still goes bad in 3-4 weeks and has caused my tank to rust internally. I now use non-ethanol gas which lasts much longer. Unfortunately, due to the short run to the mooring and back running the bowl dry isn't a practical option.