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F70 Inconsistent Running Issues

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  • F70 Inconsistent Running Issues

    I have a 2012 F70 4 Stroke. Sat for a few months without use. When getting out finally it would idle fine and at slow speed but not throttle up. Took it to the shop and they got into the fuel system, supposedly the VST etc. Ran great for a few trips then suddenly acted up after stopping to fish on the third trip. Would barely run when I went to leave and I limped home.

    Sent the fuel injectors out, one ran lean, one flooded. Brought back to spec but the lean needed to be replaced with an OEM. I drained the old gas (ethanol - shame), replaced the anti siphon valve which was bad, fuel cup filter, new plugs and waiting on a Racor separator. The fuel joint at the motor wouldn't always allow gas to be pumped thru so replaced it as well. Been testing it with an auxiliary tank and fresh gas. LP pump is working fine.

    But now it will either (A) Not want to idle (B) Idle fine but die going into gear or (C) idle fine, go into gear fine but die coming back to neutral. Frustrating inconsistency and seems to vary every time I fool with it. I did notice that that if I drain the VST and pump it back up it will idle nice and go into gear running smooth but die coming back to neutral. Also I unplugged the little switch assembly on the linkage thinking that was the culprit - tested it with an ohm meter - it's open when in gear and closed in neutral. That's supposed to be the case from I can tell.

    Pulling my hair out now. Any advice on where to go from here would be greatly appreciated! I may have to cart it back to the shop but that'll be my last resort as they were quite pricey!

    Thanks!

  • #2
    Sounds like the old crappy gas, (that the shop left in) re-contaminated your system..

    It should have ALL come out when servicing the fuel system..

    I'd start with draining and catching what comes out of the VST and inspecting that..
    Scott
    1997 Angler 204, Center Console powered by a 2006 Yamaha F150TXR

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    • #3
      Thanks Townsends. The first time I drained the VST I got some debris out (see pic). Not getting that now that I'm using the fresh gas in the can. Do you think it could foul up the VST in a few hours after it was serviced? I know they were in it at the shop since I had to bring it back because it was leaking gas where they rolled the gasket. I'm not wanting to dig into it but think I can handle it. Was also wondering if the TPS could be an issue. Need to figure out how to rule that out.


      VST Gas.JPG


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      • #4
        Well, never did go into the VST. Put in a new TSP, putting it all back together and she's a sweet running thing now! Thanks!

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