Tohatsu 18HP 4 Stroke Auto By Start Problem

[cinchy]

My Auto By Starter seems to be working properly, but the engine will only idle when I lift it up so that the o-ring that it part of it is slightly above the carb. Further out, its stalls. Further in, it stalls. Problem began after I removed the ABS to clean the carb. May have lost part of the ABS, but cannot find a break down of the components that make it up anywhere. Is anyone familiar with the stainless piston, small spring and brass needle that go into the carb? Are there any other small parts that could have fallen off?

 

[pvanv]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

On the MFS18B2, the ABS solenoid is serviced as an assembly; there aren't any small bits available. It's a combination electric heater and expanding chamber that drives the brass pin out as the motor runs. You can test it by applying 12v to the 2 wires when cold, and over the course of a couple of minutes, the pin should travel out. The brass spring is there to retain the pin. As long as you haven't lost the pin or spring, you probably have all the parts.

Essentially, as the ABS warms, and the pin advances, the tip of the pin restricts fuel flow, leaning the low-speed circuit of the carb the warmer the solenoid gets. Similar action to slowly easing off the choke on a carb that has a butterfly-choke assembly, only fully automatic, They are extremely accurate and very reliable, but they do occasionally fail.

The o-ring must be sealed in the bore, or vacuum is lost, and the whole mixture adjustment system stops working correctly. Assuming that you have not damaged the ABS or lost a piece of it, odds are that there is something amiss inside the carb body -- possibly a bit of leftover varnish or crud in that circuit.

I would test the ABS solenoid, and verify that it is complete. If all seems OK there, pull the carb and soak it again, followed by a liberal blow-out with generic carb spray.

 

[cinchy]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Thanks Captain. I didn't think that I had lost anything. I have the carb off again. I blew it out with air after soaking. I'll try blowing it out with carb cleaner. If this doesn't work, any other ideas?

 

[pvanv]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Did you test the ABS solenoid? Did you disassemble and clean the accelerator pump and its bore?

 

[cinchy]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Sprayed it out with carb cleaner and ran soft copper wire through all passages that I could. Viola! Brother, if this carb is not sterilized and dissinfected, it just won't work. However, the fact that you can take it off, take it appart with a phillips and a 10mm ratchet is great. Thanks for getting back to me brother. You gave me hope.

 

[pvanv]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Glad it worked out.

Beware of pushing any wires through passages -- especially jets (which are soft brass), because any scratches can cause weird fuel flow patterns, which can lead to inconsistencies in the mixture depending on throttle position and vacuum.

ANY modern EPA-rated carb [of any brand] will be super-sensitive to varnishing. In order to meet emissions standards, the passages are longer and narrower (in order to get more thorough air/fuel emulsions while running leaner than the older-style carbs). Because of that, minor varnishing can be a major issue. Add in today's poor fuel, and you must be vigilant. Thus you must run the carb dry at the end of the day (or drain it) unless you know you will be running again the next day. If fuel is allowed to sit in the carb and evaporate for about a week or two, you will start getting varnishing problems.

Adding a water-separating filter near the motor is also a good idea. Avoiding E10 fuel is good practice as well. If the fuel has a chance of going beyond 30 days before it's consumed, a good stabilizer (we use K-100 products) is also recommended.

 

[cinchy]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

I used very thin strand from a soft stranded copper wire, so no chances of scratching. Only running non-ethanol from now on. Will add water seperator AND additive AND run dry AND drain (if there's anything left in the carb). What do you think about blowing (low pressure) air through the fuel inlet on the carb also? I want to get all traces of fuel out.

 

[pvanv]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Ah. Our secret recipe in our shop. To be expedient, when winterizing, we open the carb drain, and then disconnect the fuel line at the carb, and apply low pressure air to the fuel inlet, effectively purging old fuel from the lines, filter, and fuel pump. But beware: you can blow out the fuel pump if you get too aggressive.

 

[cinchy]

Re: Tohatsu 18HP 4 Stroke Auto By Start Problem

Now if I could just figure out Colonel Sanders recipe! Fortunatley no winterizing is necessary in South Florida. Our life jackets are bullet-proof though, just in case you run across some smugglers out on the water!