115 HP 4 stroke low RPM vibration?

T

trout killer

Recruit
Joined
Mar 5, 2012
Messages
4
I have 2001 4 stroke 115 HP EFI Merc runs great except @ idle, sometimes it shakes like it's missing, (700RPM) It starts very easy. I can take it up to 1000 & it will smooth out. It doesn't do this all the time.Also, (sometimes idling at 1000RPM it will increase RPMs to around 1300 to 1400. Just had a complete valve & head job done on it, so it has new plugs & everything set to "factory" Rechecked the compression & fuel pressure, both OK.
 
1

1nebel0

Chief Petty Officer
Joined
Nov 28, 2005
Messages
512
Re: 115 HP 4 stroke low RPM vibration?

Send your fuel injectors out to be flowed and cleaned...should be done every couple of years given the great fuel our country is using...be sure and have a racor water separator/fuel filter on the boat..It is the first thing I do on every boat I buy and sell...
 
Faztbullet

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,938
Re: 115 HP 4 stroke low RPM vibration?

Also check the IAC valve......
 
SparkieBoat

SparkieBoat

Captain
Joined
Aug 17, 2009
Messages
3,643
Re: 115 HP 4 stroke low RPM vibration?

faz is correct, I had a 03 yammy 115, same motor as you have, those valve go bad, if it gets real hot to the touch, the valve is most likely bad. and it can damage your computer. also it is good to send your injectors off every few years for cleaning and flow test. clean out vst chamber yearly, including the little filter at the bottom of your HP fuel pump. also you need to check you TPS, they go bad regular also. unless you really have the right tools and know how these motors are best left to a trained mechanic.
 
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