Dealer or someone with HPDI expertise?

[Jon Tallis]

Originally Posted by mhb100

What Psi are your cylinders giving?

No's 1-5 are 110psi and no.6 105psi so all good there

[Jon Tallis]

Originally Posted by mhb100

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!)

[Jon Tallis]

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........

[mhb100]

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.

[mhb100]

Originally Posted by mhb100

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"

[wellhouse]

did you check the fuel pressure under load?

[Jon Tallis]

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?

[wellhouse]

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.

[mhb100]

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?

[gpsguru]

Originally Posted by Jon Tallis

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 ? ............

[simonl]

How's it going? I think I'd consider using a multi channel scope/logger, e.g. picoscope etc, to help diagnose. Have a look at the picoscope web site to see some of the approaches they use for diagnosing cars. there's some clever people doing smart stuff, much of which could be paralleled on an HPDI.

[mhb100]

Hi, did you get to the bottom of this in the end?

[Jon Tallis]

Still no further forward on this and thinking towards next season.
Last request for help - does anyone know anyone in the UK who truly understands how the 150HPDI works and might be willing to look at mine?

[Pipster100]

If you haven’t had your injectors properly cleaned then I’d recommend this prior to doing any further work. I also have a 150 yam and my friend has a 115 yam, he’s had the same issue you describe and it was a low flow on the injectors. If you can remove them, then post them to Rock Marine Services in Cornwall (no I don’t have any connection with them just a very satisfied customer) they can flow test and properly clean them for you, they’ll also give you a report on the flow rate before and after cleaning. It’s surprising just how the tiniest bit of a blockage can stop your performance. I’d also recommend a new O’ring kit before refitting especially if the injectors have been out a couple of times. Hope this is of some help to you. Good luck

[simonl]

Wherever you take it you'll benefit from providing a detailed explanation of symptoms & diagnostics undertaken plus results. It might be a worthwhile exercise posting that here as a consolidated statement- many won't trawl back through 4 pages.

[Tony Hill]

That was many years ago. Last ones used maybe 2004. They were basically bomb proof. Ok the Filter in the VST needed changing and the high pressure fuel filter you threw away but that was basically all our problems apart from cylinder head gaskets at about 1800 hours.
Philip from Yampower, Glasgow sorts all our engines and continues to do so.
Glasgow is a long way from the south coast

Tony

[Jon Tallis]

It's already the middle of the season and I can see me missing ANOTHER summer unless I can get this sorted :-( Have done a few more things but still not sorted the problem. For a recap - and to stop anyone having to scroll back - here's the problem:-

Symptoms, that were intermittent but are now constant are simply a loss of power - maybe 20-30hp? Can't get above 5000 / 36kts when loaded - used to rev out to 5600 / 40-42kts, but engine is silky smooth - no misfires no hesitation, just feels like it's running 3/4 throttle. Plug condition suggest engine is running borderline lean.

Work / Investigation done

• Changed secret filters, main inlet filter, VST internal filter and VST > HP pump filter
• Checked compressions - all consistent and in-range
• 6 new coils and plug caps (some were arcing under spark-gap test)
• New throttle position sensor (voltage was slightly out of range on YDS but new one is exactly the same)
• Cleaned, then changed the O2 sensor (voltage was flat-line on YDS but no fault code - nobody can tell when when in the rev-range the O2 sensor is operational anyway)
  • Rebuild the two vacuum fuel pumps
• Injectors professionally overhauled
• Re-checked on YDS - no faults at idle. Cant see any issues under load including fuel pressures that all look spot-on

I'm really running out of options now but there's one thing that doesn't look right - then inlet fuel filter is building a level of air when running. Drops down to about 1/2 way down the filter element which means the vacuum pumps must be drawing air, but I can't work out where it's coming from. I've changed the fuel filter seal (twice), checked the sealing faces (all perfect), air tested the filter assembly (bubble test @ 20psi - no leaks), run the engine off a separate tank (no better), run the engine off the separate tank with the fuel line dipped direct into the fuel (better again), switched back onto the main tank with the fuel line dipped directly into the fuel (back to square one, but the fuel line and primer are both only a season old).
I've posted a video here >

https://www.youtube.com/watch?v=XJ9xEaLgTaI

showing the air building up - can anyone tell me if this is normal?

[jwalker]

I'll run my engine for you to check what goes on in the filter housing but at the mo it's thunder storms and pishin doon so you'll have to be patient. It is entirely possible that the space above the fuel is not air but petrol vapour.

However, you say you've had the injectors overhauled, well I've taken one apart, just to see how they function and I can't imagine how they can be overhauled since they're welded closed and took a fair bit of hacksawing to open up..hmm, I'm a bit sceptical there.

Something to check because it sounds very much like you're missing a cylinder - I know you said it's super smooth at speed but the HPDI does sound super smooth even with a cylinder not firing. Really! Anyway, check the injectors. They are 12 volt units so you can apply battery volts to them. Don't hold the connection for long because they'll heat up but there is only a need to make contact then release the power - just touch the connector pins momentarily.
Right, pull the connectors off of all the injectors and move them to the side, you need to ground one of the injector's contacts to a battery negative and touch a cable from battery positive to the other injector contact. It doesn't matter which way around you connect the power. If the injector is firing you'll hear a distinct click. Check each one and listen for one which may be lazy.

I guess you've done this bit but while you're there check the injector cable connectors for battery voltage using a meter to ground, you should have battery volts at one pin of each connector with the ignition switched on. The other pin connects to the ECU and the ECU grounds it to energise the injector. Once you've identified the 12v pin, use a lamp to connect to that pin to confirm that there's no wiring issue preventing enough current flow to the injector. The lamp should light. An automotive 21watt flasher bulb should do nicely.

If the weather's ok tomorrow, (Sunday) I'll check the filter housing for you.

... run the engine off a separate tank (no better), run the engine off the separate tank with the fuel line dipped direct into the fuel (better again),

Can you better explain what you mean by this? 'Better again'

[Jon Tallis]

Originally Posted by jwalker

I'll run my engine for you to check what goes on in the filter housing but at the mo it's thunder storms and pishin doon so you'll have to be patient. It is entirely possible that the space above the fuel is not air but petrol vapour.

However, you say you've had the injectors overhauled, well I've taken one apart, just to see how they function and I can't imagine how they can be overhauled since they're welded closed and took a fair bit of hacksawing to open up..hmm, I'm a bit sceptical there.

Something to check because it sounds very much like you're missing a cylinder - I know you said it's super smooth at speed but the HPDI does sound super smooth even with a cylinder not firing. Really! Anyway, check the injectors. They are 12 volt units so you can apply battery volts to them. Don't hold the connection for long because they'll heat up but there is only a need to make contact then release the power - just touch the connector pins momentarily.
Right, pull the connectors off of all the injectors and move them to the side, you need to ground one of the injector's contacts to a battery negative and touch a cable from battery positive to the other injector contact. It doesn't matter which way around you connect the power. If the injector is firing you'll hear a distinct click. Check each one and listen for one which may be lazy.

I guess you've done this bit but while you're there check the injector cable connectors for battery voltage using a meter to ground, you should have battery volts at one pin of each connector with the ignition switched on. The other pin connects to the ECU and the ECU grounds it to energise the injector. Once you've identified the 12v pin, use a lamp to connect to that pin to confirm that there's no wiring issue preventing enough current flow to the injector. The lamp should light. An automotive 21watt flasher bulb should do nicely.

If the weather's ok tomorrow, (Sunday) I'll check the filter housing for you.

Can you better explain what you mean by this? 'Better again'

Thanks!
You're right, the injectors can't be "overhauled" as such, as they are totally sealed, Mine have been off and professionally flow-tested (which revealed a few issues), ultrasonically cleaned and re-tested after which they were all in-range.
That doesn't rule out a wiring / connection issue so, thanks for your prompt - I'll check that. In addition to your suggested method, it's possible to do an individual injector firing test via YDS (which I have). As you say, you can hear the injector click when it fires, also it's possible to view the spray with an endoscope down a plug-hole.

Let me know what you find with the filter - I'll be interested - I can't for the life of me work out where that air (or vapour) is coming from. J

[jwalker]

Originally Posted by Jon Tallis

.....Let me know what you find with the filter - I'll be interested - I can't for the life of me work out where that air (or vapour) is coming from. J

Both of my engines are similar to yours. When idling, if I pump the primer bulb the filter fills up instantly but the fuel level slowly drops about 30-40mm.