2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

[hawilson2]

2006 F115 occasionally stalls or stumbles on takeoff and occassionally surges while running. Backing off the throttle seems to clear it up and/or pumping primer bulb. It does not happen on any regular basis. I believe it is a gas starvation issue. I have been running a 2 micron Racor filter/water separator between my gas tank and motor for about 150 hours now. I have on order the VST filter and gasket as well as the inline filter between the low pressure fuel pump and VST and will be replacing those components soon. Is there anything else I can check that may produce these symptoms? Also, any tips on getting to the VST?

 

[SparkieBoat]

Re: 2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

I have heard of issues with the 2 micron filters..they clog too fast and restrict fuel flow. you need to check your 5v reference on each sensor..and your TPS voltage. Also touch your ISC valve and see if it gets real hot after just a few mins of running. these EFI motors are a real pain in the butt and require intense knowledge. also can you hear the ISC valve rattle after shutting the engine off?? I made a you tube of mine. http://www.youtube.com/watch?v=RKGDf7zgP80

 

[hawilson2]

Re: 2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

I have heard of issues with the 2 micron filters..they clog too fast and restrict fuel flow. you need to check your 5v reference on each sensor..and your TPS voltage. Also touch your ISC valve and see if it gets real hot after just a few mins of running. these EFI motors are a real pain in the butt and require intense knowledge. also can you hear the ISC valve rattle after shutting the engine off?? I made a you tube of mine. http://www.youtube.com/watch?v=RKGDf7zgP80

Hate to sound stupid, but which sensors are you talking about checking the voltage? Also, should I hear the ISC rattle on shutoff or not? What is normal? I do believe it makes that clicking sound for about 2-3 seconds after shutoff as yours did. I have been running the 2 micron filters for a while with no problem. I religiously use NON-ethanol fuel, tested. When this happened the first time, I changed the 2 micron filter with another and on next outing, of 5 hours runtime, no issues appeared. On next outing after 1-2 more hours stumbling and surging happened again. I could switch to a 10 micron filter but hate to let any crap thru. Any opinions on running 10 micron filters and abandoning the 2 micron filters?

 

[SparkieBoat]

Re: 2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

I know a yamaha master tech that says no to the 2 micron filters. yes it should do the rattling..you still need to check and see if isc is over heating. these efi motors are very complex and require a good deal of training to work on them..not to mention the parts are stupid high..I am selling mine and going back to a carbbed motor. I am talking about all sensors, they all run off of a 5v reference voltage produced by the ECU.

 

[hawilson2]

Re: 2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

I pulled the low pressure fuel pump. The manual said to perform 3 tests.

1) Apply 7.1 psi to pump intake; I applied 10 psi and it held 10 psi for a minute.
2) Apply 4.3 psi (8.75 in Hg) negative pressure (vacuum) to intake; I applied 10 inHg and it fell to 7 inHg in a minute
3) Apply 7.1.psi to output side; I applied 10 psi and it fell to 6 psi in a minute and continued to fall

I also pumped the ball while the pimp was off the engine but with the fuel lines still hooked up, the ball got hard and I saw no visible sign of gas escaping.

Based on these results should I get another whole pump? Rebuild this one? If I rebuild this one, which parts are needed for the rebuild. I believe this could explain the bogging issue. Any help is appreciated.

 

[douglasesanford]

Re: 2006 F115 Stalls (stumbles) on takeoff; surges on plane sometimes

Did you buy it new? How many hours on it? A way to check the injectors after you replace the filters is to run it @WOT and have someone spray carb cleaner into the intake. If it picks up mostlikley a clogged injector-you can seend them to be cleaned for 50.00 a piece.