2003 F115 hp 4 stroke problems after 15 minutes of running

[99yam40]

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

[glennbossie]

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

[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]

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

[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.

[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]

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]

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’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?

[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)...

.

..

[glennbossie]

I ran it yesterday at a little over 4k rpms, and same thing. 10 minutes in, it bogs down. As long as I don’t mess with trying it again, I can get back to the dock under 2k rpms. I took all my fuel injectors out again and found 1 with a split rubber ring next to the engine. Replaced it, but no fix. I also checked the p hole water when it bogged down, and it was only slightly warm. Squeeze bub is new, and it had fuel in it. Makes no difference to my problem if I squeeze it. It’s not collapsing either. No alarms at all any time this has happened.
I’ll try anything you suggest, because I’ve hit a dead end. I have not taken the vst tank out and checked the filters yet, but I would think it would happen everytime I tried to throttle up if they were clogged. Is this something the ecu might cause?
Thank you all for giving me some ideas. I really appreciate your time.

[TownsendsFJR1300]

Can you try running it say at 4K RPM (same time frame) and see if it acts up again?

Just trying to rule out a potential over heat issue.
With the somewhat lower RPMs, the engine isn't quite as hot and may keep running IF NOT OVERHEATING..

I gather from your previous posts, you never got an alarm when the engine "acted up"?

.

[99yam40]

all I am saying is check what is easy to check.
a spark tester or inductive timing light should show if there is spark to the plugs.

not sure how to check if cylinders are getting the proper air fuel mix.
but rail pressure to make sure it has in spec fuel pressure.
too low or too high might be a problem

[glennbossie]

99yam40 - What would cause me to lose spark to the plugs under the circumstances I’m experiencing? Coils, ecu? I know I have plenty of spark up until the time it bogs down. It generally will start up again also.
I can’t figure out why after 10 minutes it stops getting fuel, if that’s what’s happening. What would stop fuel after 10 minutes of hard running? The only fuel spot I haven’t looked into is the vst tank.

[glennbossie]

Took it back out for a try. Idled out onto the river and opened it up. Stayed at 5k rpm 25mph and it ran like a champ. At the 10 minute mark it bogged down. I dropped it back and into neutral. Restarted and headed back to the dock at 2k rpms. Anything above that and it would cut out. Stalled completely 100 ft from the dock and wouldn’t restart. Paddled in, put it on the trailer, and tried to start it again, and it started right up. No overheat, p hole water was barely warm. Bulb had fuel in it when it died. What next?