Twin f70 keeps shutting off.

[Nicturner808]

I have twin F70 and I can't keep them running. The only way to start them is pump the ball and then they will idle for a minute and bogg out. I checked the fuel water separator and other filter and didnt see anything abnormal. One was old, but that's it. I also drained the VST and all looked good. I know it's some sort of fuel problem bc it was only one engine at first and now it's both. There are very few mechanics on my island and are all months out. Any suggestions on any other areas I can clean out ? Trouble shoot? I am not very experienced in fuel systems, but can do all the services myself lower unit/ oil/water pump etc. This boat sat for a long time , but it ran good for the first 30 hrs. The engines are 2011. I posted this before so sorry if you already read this

[TownsendsFJR1300]

If one engine, I'd say the low pressure pump is the issue.

Being now both engines,you have an air leak somewhere prior to the engines.
The engine is sucking air, NOT fuel.

You need to check fuel lines, primer bulbs, fuel / water separator, etc (everything prior to the engine).

You can also verify the diagnosis by attaching a stand alone tank direct to the
engines (by-passing the entire hull fuel system)

Also, if that fuel is old and un-treated with stabilizer(or smells bad, dump it).
Your introducing a new problem into your engine...



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[Nicturner808]

Thanks Scott. I think I found the problem. Both fuel filter assembly tops are cracked an leaking. Now hopefully I can get some shipped to me asap. Bummer I can't just buy the tops

[TownsendsFJR1300]

Thanks Scott. I think I found the problem. Both fuel filter assembly tops are cracked an leaking. Now hopefully I can get some shipped to me asap. Bummer I can't just buy the tops

Excellent!

That's great, but why did they crack?

That's a first for any engine (reading here)... You may call mama Yamaha and inquire if you can't find why (just to prevent a future failure / fire hazard.)

Look at the parts diagram (above in RED, "Purchase Yamaha Parts) and make sure you have all rubber grommits / parts etc are there.

Dunno if you got the engines used, someone could have dinked with it, removed something, etc..


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