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Old 22 July 2018, 17:00   #21
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What Psi are your cylinders giving?
No's 1-5 are 110psi and no.6 105psi so all good there
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Old 22 July 2018, 17:01   #22
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When you changed mystery filters how many did you change? and did you change the ones in the injectors?
8 mystery filters - 6 in the injectors and 2 in the HP pump (last one was an absolute swine!)
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Old 22 July 2018, 17:05   #23
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Update from the weekend.
both LP fuel pumps rebuild (internals looked OK).
compression pressures checked - all over 105psi
Injector resistances checked - all 1ohm
coil resistances checked - all between 2 - 2.2ohm
Fiddled with TPS at idle to enrich mixture - no notable change from O2 sensor, BUT i did notice when starting it was showing 0.06V which dropped to 0.02 within 60 secs ???
Injector patterns inspected with borescope - unfortunately not really good enough to see much.
Didn't get as far as the water due to other jobs but planning a sea trial Tuesday - watch this space........
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Old 23 July 2018, 14:13   #24
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You've been busy, and that all looks good. Not sure about the o2 as my hpdi does not have one so never learnt about the diagnostics. All your electrics look fine, as does your psi, so we're kind of back to perhaps fuel supply. You seem to have replaced all filters, the only one I think you've not mentioned is the one inside the top of the vst lid as part of fuel regulator, which is just a mesh. I also thought you had 3 mystery filter on a 150 not 2. 2 facing and one underneath but could be wrong. I'll check. I have found a post of someone in USA lost some top end and found it was the needle value in top of vst restricting flow. Perhaps a long shot but cleaning both of these at least means you've done the whole system.
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Old 23 July 2018, 14:39   #25
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You've been busy, and that all looks good. Not sure about the o2 as my hpdi does not have one so never learnt about the diagnostics. All your electrics look fine, as does your psi, so we're kind of back to perhaps fuel supply. You seem to have replaced all filters, the only one I think you've not mentioned is the one inside the top of the vst lid as part of fuel regulator, which is just a mesh. I also thought you had 3 mystery filter on a 150 not 2. 2 facing and one underneath but could be wrong. I'll check. I have found a post of someone in USA lost some top end and found it was the needle value in top of vst restricting flow. Perhaps a long shot but cleaning both of these at least means you've done the whole system.
Checked and "The older style HPDI pumps were fitted with three of these HPDI mystery filters. Two in the actual pump body and one in the pressure regulator. The new style HPDI pumps are fitted with two “mystery filters” per pump. IE two for a single pump and four for a double pump. Both located in the pump body"
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Old 23 July 2018, 16:10   #26
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did you check the fuel pressure under load?
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Old 26 July 2018, 16:32   #27
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Update from sea trials:-
Very lumpy and slow idle initially when cold. Tried both YDS "drop cylinder" test and pulling off plug leads one at a time - all pretty inconclusive.
Idle fine once warm.

Under way at 1500-1800 revs, slight misfire evident, fuel pressures all good (4.7 bar & 700 psi), Oxygen sensor flat at 0.02 volts.
At full taps, still only 5200 RPM, fuel pressures good (5.0 Bar & 716 psi), Oxygen sensor still flat.
No fault codes on YDS.

Priming bulb does go slightly soft when running but pumping the bulb doesn't make any diffference.

If I still had a fuel problem, surely it'd be showing as low fuel pressure?

So now I'm thinking O2 sensor and /or coils - all V expensive to change on a hunch

Any ideas?
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Old 27 July 2018, 01:58   #28
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now that it looks like the fuel pressure has been ruled out as a problem, i'd be looking for a slightly sticking injector/injectors, bear in mind what i said on the phone about the issues removing them, best idea is to remove the fuel line to the injector then inject/squirt injector cleaner into the injector whilst operating the injector solenoid - you can do this with a low powered radio battery by just tapping one terminal with the other terminal connected to the battery to make the circuit. Then leave to soak. Other way is to heavily dose the fuel filter or vst. After that you are really into the coils and leads both of which can be problematical normally on the lead it is where the lead joins the cap where it breaks down. You could buy/borrow one coil and replace one at a time until you have ruled out or solved the problem. Good luck.
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Old 28 July 2018, 17:32   #29
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Did you check that needle value and filter inside the top of the vst? I know it's a long shot but I did find a post on a USA forum with the same reduced top end issue you have and I think it's the only part of your fuel system untouched. But the fact that you say you had a misfire would suggest your back to intermittent electrical problem or perhaps injector. I doubt it's an injector as I think it would be a more noticeable issue, but they are not hard to get out but my view is spraying something like Seafoam is probably a bit of a waste of time as these really need to be cleaned properly and flow tested so you know they are performing. Hpdi more than most need an even spray. It's cheap to get them cleaned, and quick, but you spend more on o rings and seals which on high presure system your best not to reuse. I have imported many hpdi second hand and refurbished parts from usa which even after duties have been much cheaper, might be worth picking up a spare coil. I know you have tested all the coils, plug heads and plugs but I'd be tempted to test them again. I've had a plug go on an hpdi after only 4 hours, and oddly intermittent. Where is the boat based?
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Old 28 July 2018, 18:24   #30
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Quote:
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Update from sea trials:-

Under way at 1500-1800 revs, slight misfire evident, fuel pressures all good (4.7 bar & 700 psi), Oxygen sensor flat at 0.02 volts.
At full taps, still only 5200 RPM, fuel pressures good (5.0 Bar & 716 psi), Oxygen sensor still flat.



Is the O2 sensor narrowband or wideband ? ............
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