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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?
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Hey Herb, I can't help you, but master tech Rodbolt should be here soon to sort you out. He's a blunt kinda guy but we all love him anyway! Goodluck,
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ditch the 2 micron filter.
its to restrictive.
go back with the Yamaha reccomended 10 micron filter.
you also should pull the injectors and clean the filters or send them off for cleaning.Comment
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I am returning the 2 micron and getting the 10 micron Racor filters today. Any pointers about getting to the VST and cleaning the injector screens? Can I reuse the intake manifold gasket if I have to remove it and do so carefully? Also, considering soaking the plunger part of the ISC (IAC) in carb cleaner. Is that ok to do? Recommended?
I am due for a VST filter change anyway. I have 425 hours on the engine and I believe the maintenance schedule calls for inspecting/replacing the vst filter every 500 hours if running with a 10 micron filter.Last edited by herb.wilson@uno.edu; 04-06-2011, 11:19 AM.Comment
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I used a new intake gasket..but Rod told me I could have reused the old one. I soaked my isc valve for 2 days in sea foam..it worked for me, so far anyway. Rod recommends VST cleaning yearly. on cleaning VST , you just have to remove the intake manifold to get to it..I replaced the phillips head screws with allen head ones, cause I stripped out 3 of them getting them out and did not want to reuse them..hard to find little screws though, but I finally found a local place that had SS metric screws. I disconnected as little as possible..if you disconnect the high pressure fuel line going to the rail be sure to use an appropriate clamp, not the regular ones..I used one for auto high pressure fuel lines. I also replaced the screws on the TPS..who was the complete frikin idiot that came out with a concave torx ??? He should be shot on sight. I mean stop the madness.
get a new seal for the VST top.
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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.Comment
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Sounds like the pump is ok. A bad diaphragm and vacuum would fall very quickly.Stanley Islander 19, 2006 Yamaha F150TLRC. Ottawa, Canada
16' York River, 1986 Yamaha PRO 50.Comment
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I can tell you from experience, repairs on the EFI/DI motors are almost never simple. These motors have a very complex system in which it requires extensive understanding of the overall operation of the motor in order to properly diagnose a problem. I just spent 3 months working on mine and doing a crash course in EFI motors. If you are willing to invest a lot of time into this project, and have a good mechanical ability to begin with, you need to begin to learn each component of the system (every sensor, ISC valve, fuel pumps, rail pressures, injector knowledge, ECU) and how to set/test each component. you will need a fuel pressure gauge, computer connections and a lap top and program. There is a post in here about our improvised $30 cable, you will have to do it that way cause yammy has their $300++ cables back ordered for at least 6 months, maybe longer. Did you ever clean out your VST filter??Comment
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As far as the pump goes, a rebuild is out of the question come to find out. I thought that maybe the one of the check valves in the intake and output ports were bad. A new pump is around $134. I hate to spend the money if the pump is still good. Not sure if all the tests should hold their pressures for some time without falling at all. Can anyone answer that?
Haven;t cleaned the vst yet but I'm getting there.
I can make the cable. How about the program? Any ideas where that can be gotten from.Comment
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Just a quick thought-the only thing I DID NOT clean/check on my HPDI (I know different animal) was the O2 sensor and lo and behold that was the stumbling issue I had. Bad thing was I had it in my hand and was afraid to clean it. Crystal Pierz took it out and tested and cleaned it there on the lake and runs like champ (again).
Just my thoughts.Comment
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No o2 sensor on the f115 but thanks for the suggestion. Keep them coming.Comment
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Check fuel pressures if you are concerned, but I would follow Rodbolts adviceOriginally posted by herb.wilson@uno.edu View PostComment
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