Yam 115 4Stroke Hesitating/Stalls

[Lar017]

I have a 2003 Yamaha 115 4 Stroke that hesitates and/or stalls when I throttle up. Plugs were changed and gapped at around .040 and it didn't help, no water in fuel. Larry

 

[rodbolt]

Re: Yam 115 4Stroke Hesitating/Stalls

you will need some trouble shooting.<br /> if an EFI motor fails to go its broke.<br /> test the fuel rail pressure and remove the injectors for testing/inspection after making sure the ign controls and spark are there.<br /> could be the TPS is bad but usually its a fuel issue.<br /> when was the last time the engine ran properly ?

 

[GoTTwins]

Re: Yam 115 4Stroke Hesitating/Stalls

Rodbolt, Lar017 is my dad so I'll answer for him here. The boat ran fine when we ended the season in late Novenmer. We changed the oils then and ran some stabilizer through the system. He started it up last week and ran it in the driveway for a little bit and that's when it started to sputter when he brought the throttle up. I thought maybe the plugs were bad so we changed them today and it didn't help, he actually says it got worse when we changed the plugs. It we bring it up too quick it stalls. The engine probably has about 75-100 hours on it if that. Dave

 

[rodbolt]

Re: Yam 115 4Stroke Hesitating/Stalls

sounds like an injector is stuck or plugged from bad fuel.<br /> try bringing it up to 1000 RPM or so and unplug the injectors one at a time then replug it and check for RPM drop. that will isolate the cyl. the injectors are simple to remove and spray out with some carb cleaner. you can trigger them with a 12v battery and some jumper leads just dont apply voltage for long. I hook up the jumpers then take one lead and brush it past the battery and listen/feel for the click. while its basically a solinoid it wont pass the current for extended periods. a couple milliseconds is all that is nessasary.<br /> use clean engine oil on the orings at reassembly.<br /> flagship marine offers a cleaning and is reasonable and has a quick turnaround.

 

[GoTTwins]

Re: Yam 115 4Stroke Hesitating/Stalls

Thanks rodbolt, we'll be working on it this weekend. I'll give you an update. Dave