2003 F115 hp 4 stroke problems after 15 minutes of running

[TownsendsFJR1300]

S..t, I dunno..

Just throwing this out there.

Might try running with the hood OFF.
Perhaps, engine heat is screwing up the ECU. See if that makes any difference...

Also, if you have a fuel cooler, check that and make sure it isn't clogged (water side/flow of it)...

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..

[glennbossie]

I’ll try this, thank you. I’m going into the vst tank today to change the filter and see if there’s any debris in there. Thought is that there’s particulate matter in there that gets sucked against the filter causing it to starve. When I let off and leave it for a few hours, the stuff falls off, and the whole thing starts over again. It works at low rpm’s.
What’s your thoughts on this?

[99yam40]

I guess it is possible, monitoring rail pressure would help point to that.

recirculation valve not closing off might also make the low pressure pump not be able to keep the VST full at high usage RPM
If the VST is full ,but rail pressure drops then it would point to that screen/filter in VST

[glennbossie]

I opened up the vst tank today and cleaned it out and changed the filter. I’d say the screen was 70% plugged up. There were some really fine particles floating In the bowl also, so hopefully these were getting sucked up against the screen after a little while and causing my issue. I’ll report back as soon as I get it on the water to try out.

[99yam40]

try to explain where those particles came from.
filters between the tank and VST should have caught them if they came from the tank

[glennbossie]

The guy I bought the boat from purchased it new in 2003. I did the work in his garage, and he said he has never gone into the vst tank. This is 17 years of accumulation. He also never had a cannister filter water separator on that whole time. I just put it on last year when I bought it. The filter looked like it had varnish on it, as the previous owner only used ethanol. I only use non ethanol. This still might not fix my problem. We have small craft advisories until noon tomorrow, so we’ll see.

[glennbossie]

Much colder out today. Ran 53 minutes at 4500 rpm’s, but then failed again. Got back to the dock running under 2000rpm’s.

[Keithbaja]

I would highly suggest try running a aux tank. Quick, easy and works great. Aux tank and fuel line, p/blub directly to motor. No short cuts. DO NOT use any parts of the old fuel system !! I sea a lot of boats with the dreaded antisipon valve funky. By law l can't tell you to remove antisipon valve and nock out the SS ball and spring.

[glennbossie]

Changed the high pressure fuel pump and the problem is fixed.

[99yam40]

good to hear it is fixed.
I wonder if running restricted do to partial plugged could have damaged the pump.