m40c start and idle issue

[madjbs]

I have a brand new m40c which has just completed the run in period. Today I could not start the engine and noticed that the choke had been jammed on. After fixing that I managed to start the engine but now I can not run it any less than with a third throttle or it just dies. It is then very difficult to start again and I have to use a combination of choke and a lot of throttle to get it started again. I cleaned the plugs and cleaned the carb but it still is doing the same thing. I could not get the main jet out however as it was in very tight and the brass started stripping. Does anyone know what else I can do to get it running right? I think it has something to do with the pilot jet but I am not sure where it is in the carb.
Thanks

 

[MinUph]

Re: m40c start and idle issue

Brand new motor? Why not take it to the dealer.

 

[madjbs]

Re: m40c start and idle issue

I came away for the weekend and spent all of saturday afternoon trying to sort it out to no avail. The dealer is closed till next week and I would like to try and get it working so I can use it tomorrow before I have to head home after a wasted trip.

 

[pvanv]

Re: m40c start and idle issue

What is your ZIP code? Where did you manage to buy a 20-year-old motor "brand new"?

 

[madjbs]

Re: m40c start and idle issue

Hi

Actually Tohatsu still make the engine for sale in Asia, you can see it on their japanese website. I live in Thailand and bought the engine from the dealer here. They cost half the price of the m40d and a lot lot less than the tldi.
Thanks

 

[madjbs]

Re: m40c start and idle issue

I had chance to mess around with a engine a bit more today. I cleaned the plugs and carbs again and checked the fuel filter and pump. From cold the engine started easily and ran 100%, after about 45 seconds I could tell that it was starting to die at idle. It gradually gets worse untill after about 2 minutes when you cant run it on anything less than half throttle. If you let it die after it has run for a few minutes it is very hard to start and you have to use half throttle+ to get it to fire, the choke doesn't seem to affect it then.

Any ideas? I thought it was the carb but that doesn't explain why it runs from cold, also as its new it is very clean inside and I didn't find any blockages or gunk. Could it be a faulty ignition coil?

 

[pvanv]

Re: m40c start and idle issue

As I mentioned to you on the other board...

Could be a lot of things. Problems that are thermally-related can be tricky to find, and require a lot of patience, as you make a test, a change, and a test run. You could have an ignition problem or a fuel problem. If you get the motor in a condition where you have the problem, then run the ignition component tests with a good analog ohmmeter, and that will help you to rule out the ignition. Likewise, if the carb is way too rich, that would produce results similar to what you describe. Always check the plug condition. Soaking wet is typically an ignition failure. Just black is usually too rich, but if it's horribly rich, and really floods, that will give wet plugs as well.

 

[madjbs]

Re: m40c start and idle issue

Thanks for your suggestions Paul, I did some more tinkering today with your points in mind and I can say that I know for sure now that it is running far too rich. If I disconnect the fuel line as soon as it starts it runs fine until it starts to run out of fuel, If I then quickly connect the line again, give the bulb a squeeze then disconnect again, it carries on running fine for as long as I keep repeating that process. I am not too sure what this means in terms of what part of the fuel system is playing up.

Thanks again for the pointers

 

[pvanv]

Re: m40c start and idle issue

I've seen that when there was a stuck float or needle. Is your float height correct?