# Yamaha F70 VST



## CKEAT (Aug 26, 2015)

I had a crimped hose in the bilge pocket. Replaced Yamaha fuel hose and it fixed it. May not be your issue


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## Frank Ucci (Jan 20, 2019)

Do you have a water separating fuel filter? I'd guess water in the fuel or bad fuel. If you don't have a filter between the tank and the engine, you might have plugged your vst filter but I'd look elsewhere first.


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## DBStoots (Jul 9, 2011)

All the filters are fine, clean and clear. Fuel pumps out when the line is disconnected and the bulb is squeezed. What would make the fuel pump leak or fail?


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## Frank Ucci (Jan 20, 2019)

Any water in the fuel? Clogged tank vent or anti-siphon valve?


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## KCTim (Feb 7, 2017)

Have had the exact same issue, I would start with changing the fuel line and bulb, only use a Yamaha OEM though. I tried an aftermarket brand and the problem persisted until I went with a Yamaha part which fixed the issue. At worst it is still the easiest and least expensive item to start with. Good luck with it!


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## CKEAT (Aug 26, 2015)

Yep, I went with OEM Yamaha tube. Also modified a bit so it ain’t in a bind anymore.


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## JC Designs (Apr 5, 2020)

All sound advise thus far. If the vst is still suspect after checking/replacing suspect fuel system components boat side. You can pick up a fuel pressure gauge fairly cheap and get a reading. There is also a cam driven lift pump, check your oil for gas. If it smells like or visibly has gas in it, time for a new lift pump and oil/filter change. And to add to what has previously been said...

You can (A) Hook up to a known good portable tank and run.
OR My go to
(B) Install a short piece of clear tubing and a vacuum gauge post primer bulb. This will tell you if you have a restriction or are pulling air. Hope it helps, PM me if you need any specs or further guidance.


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## Capt. Moose (Dec 12, 2015)

DBStoots said:


> All the filters are fine, clean and clear. Fuel pumps out when the line is disconnected and the bulb is squeezed. What would make the fuel pump leak or fail?


There is a filter inside the VST that could be your culprit.


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## DBStoots (Jul 9, 2011)

Turns out, the fuel pump had failed. New one installed--fuel pressure back to normal, ready to rock!


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