F115 idles way to fast

[tomfishhunter]

yr 2000 F115TRXY 4 str. My motor had a periodic problem of the idle going up to 1000-1100rpm after warm up. When I would take it to the dealer it would work fine. Can't fix it if it aint broke. Now it just stays up at fast idle, and my dealer is set up to work on snowmachines now, and I want to go fish. Any body familiar with this? Thanx

 

[WillyBWright]

Re: F115 idles way to fast

Is it idling high in or out of the water? It wouldn't be unusual for any motor on muffs to idle high out of the water. Otherwise it's computer controlled and there isn't much anybody can do about it except make sure the throttle is returning all the way to idle. You should also know that it HAS to be at idle to start and run properly. Otherwise the computer sees a value it doesn't like and defaults to a program that will allow the motor to run, but not in full tune. Warm-up levers are probably the #1 cause for certain running issues that are simply operator error. Loose battery connections come in a close 2nd. You also need AT LEAST a Heavy Duty battery. If I had a dollar for every EFI that came in with problems that related directly to a Regular Duty battery... <br /><br />I'll give you an example. We had a customer come in with a SeaDoo with a Merc EFI Sport Jet. He had it to the selling dealer over and over again with odd problems and they never were able to straighten them out. I saw the problem in 10 seconds. They had put in a light-duty trolling motor battery. I put in an Extreme-Heavy-Duty battery and all their problems mysteriously went away. You'd be amazed how many dealers just put in the cheapest crap battery they can get.

 

[Silvertip]

Re: F115 idles way to fast

High idle speed on an EFI engine can be due to an air leak around the intake manifold or the idle air controller is not working properly. Throttle position sensor or misadjusted linkage are also possibilities. I doubt that electrical connections or battery size are problems in your case. The ECM requires a specific voltage to operate. Battery capacity is an issue for starting but once running, current draw is much less. If the engine starts, battery size shouldn't affect operation because the alternator is supplying the demand. Voltage below the ECM threshold will cause it to shut down.

 

[JB]

Re: F115 idles way to fast

Engine troubles go in the Troubles forum, Tom.<br /><br />I will move this to Yamaha troubles for you.

 

[bigbrownbuku]

Re: F115 idles way to fast

i would start with throttle position sensor voltage. i would also get a vacuum tester installed and check intake vacuums are corrct