2000 yamaha 115 4 stroke problem..after vst service

Riptideusa

Recruit
Joined
Aug 30, 2011
Messages
4
Hey Guys, please help me

I been through alot, but learned so much, 1st thing 1st, i have a 2000 yamaha 115 4 stroke, i put the boat away for the winter not knowing that i needed to drain the vst tank, the boat ran fine when it went into storage, when it went in this season it started up fine, idle fine, but when i reached 5000 rpms it started to drop in rpms, and held a steady 4600 rpms. changed all filters and drained fuel tank. the problem still exist, then i heard about the vst tank and the filter for the high preasure fuel pump, so off to the dealer it went, i asked them to change the vst filter and they tryed to sell me a complete fuel system, $1800...well i took the boat home and got a service manual, ripped into it and changed the vst filter, it was all dirty, 2/3 clogged, i ran the boat on the hose for a few min after putting it back together, it ran perfect, idle perfect, so the wet test was next, dropped it in and it started up fine, and i solved the problem of reaching wot full rpms. i ran the boat for 15 min or more, as i was bringing it in to thr ramp and backing off the trottle it started bogging and spittin, and when i took it out of gear it would not idle smooth, and would eventually stall out, when i went to start it the rpms shot to 3000 rpms for 20 seconds then drop and would run rough then stall. i kept trying it and it still continues to shoot up to 3000rpms and drop then run rough and stall. i cleaned the ics and vst filter is clear...it still runs great when underway...i sent injectors out and cleaned them, new thermostat...still have the problem


thanks so much
 

patbalmos

Seaman
Joined
Aug 2, 2011
Messages
59
Re: 2000 yamaha 115 4 stroke problem..after vst service

Have you checked all of the small vaccume lines that are above and around the VST to make sure one did not come loose when you put it back together. Also check your VST and make sure that the needle valve is shutting of the gas completely when it fills up. It could have a small piece of rubber or dirt in the needle causing it to overflow out the vent tube and dumping raw gas into your intake. The vent line goes from the top of the vst to the black air intake box.
 

Riptideusa

Recruit
Joined
Aug 30, 2011
Messages
4
Re: 2000 yamaha 115 4 stroke problem..after vst service

thanks for the advice..ill check that ouy today

eric
 
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