I have a 2006 (?) 20 horse four stroke outboard. The engine runs fine, most of the time. However, when moving forward at idle speed, the engine will shut off, after about three minutes. The engine fires right back up, as if nothing had happened. If accelerating, sometimes it will hesitate a bit, or sometimes it will 'surge" - speed up, then slow down, over and over, until being placed in neutral, running a few minutes, the it's fine. however 99% of the time, it will take off and run fine, until idling once again, and then it will cut off, only to fire right back up.

With my limited outboard knowledge, I am assuming this is a fuel issue. I don't think the carb is emptying out and then shutting the engine off, since it will fire right up. If it were empty of fuel I don't think it would do so. I have replace the fuel line filter, but not the one located next to the block, on the actual engine. I cannot image what is going on, that it will not run at idle, I have adjusted the idle speed, only to have it running too fast to put into gear, or slow it dies in idle. There seems to be no happy medium. This erratic behavior of messing up and still having the ability to run great is frustrating to say the least. I cannot help but imagine it is something extremely minor,

I am contemplating removing the engine fuel filter, and only having the inline filter on the fuel tank line, to see if this fixes it. I attempted to install a water filter between the fuel tank and engine, but could not get fuel to travel through it, as if the engine did not have the fuel pump strength to pull the fuel through, so water could be an issue...?

I took it to a local dealer and they were not help at all.

Sorry for the long thread. Any ideas would be most helpful. Thanks so much...

 

Check the TPS.

 

Thanks, but what is TPS?

 

Thanks. I had to google TPS, throttle position sensor - and it's symptoms of being bad sound exactly like what engine is doing. I boldly assume this a replaceable part... I'll try to find it's location on the engine, and see if I can find one. Is there a way to test it first? thanks again. I hope this is it!

 

Could start by cleaning the TB (throttle body) real good. The TPS is at the TB.

 

grcauto: thanks for the help thus far. I went to a local Honda dealer this morning. He could not find a listing for a TPS anywhere in his computer. He was surprised that I was asking for one for such a small outboard, that they are usually on larger motors. He did find a listing for a "auto by starter assembly". If you are not familiar with this, it sets on the carb, and seems to control the fuel entering the throttle body, just on the intake manifold side of the carb's butterfly valve. The parts person at the dealer, was not familiar with the "auto by starter assembly" part, in regards to what it does, so he could not tell me if it was the problem. I ran 12 volts through the part, and saw no reaction at all, but I don't know if there should have been a reaction (I would have guessed there should have been).

I am having difficulty finding information on this part on line. Do you know anything about it? Should it respond to the voltage input? Does this take the place of the TPS? Thanks much...

 

After further study, it seems the auto bystart assembly is for cold engine starting. And that the movement of the needle on the part, is very minor, and hard to perceive without precise measurements, which I did not have. Also checked the continuity of the part, and that seems fine. So, I am assuming this is not the issue... Any ideas are greatly appreciated - Thanks much..

 

Would a faulty ECU cause this issue? I assume I would have to take it to a dealer to have it checked????