2004 Yamaha 115 4-stroke cuts off at idle

[msboat88]

I have a 2004 115 4-stroke on my pontoon. I have had this problem off and on for three years now. The motor cranks good and runs well for the first hour or so, then once the engine is hot the motor will not idle. I can run the motor in nuetral at a high rpm and runs with no problem, but once I try to idle it will shut down every time. I took it to the dealer twice the first year and they thought that they had it fixed but did not. The problem is getting more frequent now. Any suggestions? Thanks.

 

[devildg4671]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

I'm currently having the same problem. Did you by any chance find the problem ?

 

[SparkieBoat]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

have injectors cleaned and flow tested, clean VST chamber and screen on bottom of fuel pump..replace ALL filters. check fuel pressure at rail while idle and while running..try new plugs first

 

[sdsaw]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

As previously said, check the fuel rail pressure when the problem is occurring.

I had a intermittent problem that would occur after running for an hour or so. When slowing down to near idle speed, the motor would start to hiccup and sometimes stall.
Kinda seemed like it was starving for fuel. This went on for a few years and progressively got worst
After making sure that the fuel pressure was correct as the problem was occurring I traced it down to a failing throttle position sensor that would get slightly out of spec
You will need a digital volt meter and a test harness that plugs in between the TPS and CPU and need to check the voltage output of the TPS when the problem is occurring
I bought a factory test harness for testing the TPS but you can modify the stock harness to run this test. I might have a picture to show how to mod the harness

 

[sdsaw]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

Just noticed that this thread is from 2009
I guess my response is for devildg4671

 

[sdsaw]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

This is for anybody that might be searching through the archives
I have the Mercury version that uses the Yamaha powerhead
This is the factory TPS test harness that will set you back around $35.00 or more
You can modify the stock harness by splicing in three wires and sealing the splice with shrink tubing

You use the black and pink wires along with a digital volt meter to check the voltage output of the Throttle Position Sensor

Output voltage @ idle (750 rpm) - 0.718 - 0.746

If you are having running issues at idle and your readings are not within these specs, your TPS is bad or failing

There have been several threads involving mysterious stalling issues that have gone unresolved and I believe that this may be the cause of some of them. It was the cause of mine

Hope this helps somebody

 

[SparkieBoat]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

I did not notice how old the thread was, that is great info SD. devil, you should always start your own thread, hijacking a thread is frowned upon for various reasons.

 

[MERCURY737]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

i did not notice how old the thread was, that is great info sd. Devil, you should always start your own thread, hijacking a thread is frowned upon for various reasons.

well as long as the information is usefull like this i think it's fine.

I shall splice wires and buy dig volt meter. But if you are running the boat with the yds connected and laptop secured, would you see if tps goes crazy/ (spec out of range= window red) ?

Thanks (dealing with poor idle/ stalling issues on both motors)

mako 221 twin 115 4 strokes

 

[sdsaw]

Re: 2004 Yamaha 115 4-stroke cuts off at idle

well as long as the information is usefull like this i think it's fine.

I shall splice wires and buy dig volt meter. But if you are running the boat with the yds connected and laptop secured, would you see if tps goes crazy/ (spec out of range= window red) ?

Thanks (dealing with poor idle/ stalling issues on both motors)

mako 221 twin 115 4 strokes

Don't know what the laptop will show because I only tested the TPS with a volt meter
I can tell you this, the ECM did not have any codes stored which would have indicated that it was getting an "out of specs" output from the TPS
You have to run the test while the problem is occurring because in my case, the TPS output would return to normal and the motor would run fine again