Dealer or someone with HPDI expertise?

Jon Tallis · 17 July 2018, 21:54

Having big problems with my up-to-now super reliable and awesome 2001 Yam 150HPDI. Local dealer not much help as he's never seen another one. Can anyone recommend a dealer in the UK (south ideally) or anyone else with real expertise in diagnosing these engines?

simonl · 17 July 2018, 21:58

What are the symptoms? have you/they hooked up Yam Diagnostics?

Jon Tallis · 18 July 2018, 18:43

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.
Have changed all filters (including the VST internal, VST to HP pump and all the 'secret' filters), plug caps (two of which were arcing), changed plugs and plug caps, Changed Throttle position sensor (looked like it was giving low voltage but new one is the same), cleaned oxygen sensor.
YDS shows no fault codes and everything including fuel pressure looks in order on diagnostics.
I'm £1k in for parts and dealer labour but given up with the dealer now - more checks tonight - injector resistances, coil resistances etc.

Any ideas?

Xk59D · 18 July 2018, 19:01

Those are really popular across the pond, maybe worth joining a USA forum or speak to Davie on here, big yam dealer in Scotland can maybe point you somewhere.

jwalker · 18 July 2018, 19:54

Just could be this, post# 39.

http://www.rib.net/forum/f16/ive-got...toy-77903.html

Chanchan168 · 18 July 2018, 20:03

Search for Wellhouse on here.

He’s an active member that helped me out a great deal with my 150 hpdi

Jon Tallis · 18 July 2018, 20:07

Quote:

Originally Posted by jwalker

Just could be this, post# 39.

http://www.rib.net/forum/f16/ive-got...toy-77903.html

Not that sadly - picks up perfectly from 4 to 6 and is silky smooth even when low on power. Thanks for the tip though. Update coming below

Jon Tallis · 18 July 2018, 20:08

Quote:

Originally Posted by Chanchan168

Search for Wellhouse on here.

He’s an active member that helped me out a great deal with my 150 hpdi

Had a long chat with him on the phone today - really helpful and gave me some stuff to follow up

Orwell boy · 18 July 2018, 20:13

just prohably totally unrealistic but someone has,nt swapped your prop ?

Chanchan168 · 18 July 2018, 20:14

Brilliant news Jon. He’s got a wealth of knowledge and is always happy to help.

Hopefully you’ll get it sorted. I know bhg marine do parts too as I’ve totally rewired mine.

Good luck

Jon Tallis · 18 July 2018, 20:28

New TPS is definitely under-reading (3.99 Volts at wide-open / corresponds to 75' open on YDS). I can't account for this as input voltage is correct (5.0 Volts), throttles are coming to within a mil or two of their stops and there's no lost motion in the shaft to the TPS........however the plot thickens.....
Running YDS engine monitor at idle and up to 1600 rpm in gear (fastest I can safely go on muffs), Oxygen sensor voltage is basically flat - wavers between 0.2-0.3 volts. So I have a theory..........
Fuel control must be closed-loop at at least some rev ranges (otherwise why would it have an oxygen sensor?), maybe open loop, based on engine speed and throttle position at others. If the Oxygen sensor were working, it would adjust fuelling at least in its closed-loop range, based on the O2 sensor, adjusting for any discrepancies in the TPS. However if the O2 sensor has failed, it will have to resort to open-loop fuel control, the only inputs it's got being engine speed and throttle control. If it thinks the throttles are only 75' open when they're infact 90', it'll under fuel, run lean and make less power - exactly what I'm seeing.

So, a few questions:-

Does anyone kow the fuel control strategy for these engines (open loop / closed loop and when it runs in each)
Does anyone know how to test the O2 sensor?
Does anyone have a spare O2 sensor (£600 for a new one - kinda expensive to just try it)
Anything I've missed?

Also - one strange thing. When I do a "drop cylinder" test at idle via YDS, the engine speed increases when the cylinder is dropped (from 700 to around 1300 revs). It's exactly the same for all 6 cylinders. Anyone come across this before?

Incidentally fuel pressures are spot on at 5bar MP and 700psi HP

Tomorrow I'll be checking the resistances of all the injectors & coils as a basic check, however I can't find the resistance specifications in the Yam workshop manuals - does anyone know them?

simonl · 19 July 2018, 11:19

I have the same engine, but I've thankfully not had to get in as deep as you've gone.
If nobody can give you stock answers then I can get measuring stuff for you

simonl · 19 July 2018, 11:42

https://www.youtube.com/watch?v=WDuBVZk5_bo

worth trying..

Good article https://www.thehulltruth.com/335856-post6.html

simonl · 19 July 2018, 12:11

Quote:

Originally Posted by Jon Tallis

New TPS is definitely under-reading (3.99 Volts at wide-open / corresponds to 75' open on YDS). I can't account for this as input voltage is correct (5.0 Volts), throttles are coming to within a mil or two of their stops and there's no lost motion in the shaft to the TPS........however the plot thickens.....
Running YDS engine monitor at idle and up to 1600 rpm in gear (fastest I can safely go on muffs), Oxygen sensor voltage is basically flat - wavers between 0.2-0.3 volts.

Have you tried depriving it of air, making the mixture richer to look for changes in the lambda sensor voltage?

Jon Tallis · 20 July 2018, 21:35

Adjusting the TPS at idle would definitely do that. Will try it tomorrow, you're right will definitely show up a non-functioning O2 sensor - if it runs closed loop at idle that is??

Quote:

Originally Posted by simonl

Have you tried depriving it of air, making the mixture richer to look for changes in the lambda sensor voltage?

simonl · 20 July 2018, 22:50

Quote:

Originally Posted by Jon Tallis

Adjusting the TPS at idle would definitely do that. Will try it tomorrow, you're right will definitely show up a non-functioning O2 sensor - if it runs closed loop at idle that is??

I can't see that it would matter if it's closed or open loop for this test - it'll change the sensor output. Whether the ECU acts upon that is another matter...

mhb100 · 22 July 2018, 14:30

I thought the o2 did very little above 1500 revs, but my hpdi 250 does not have one. You have checked what I would have suggested as it's silky smooth both on tick over and at above 4000. If not I'd have suggested vacuum /throttle sync /tps, etc. You've done all the filters but what is YDS saying about your HP Psi. I'd take it for a spin and take some measurements. Hook up by removing trim switch so you can keep cowling on. I'll look in by workshop manual. Personally I'd go on the USA forum like the Hull Truth and marineengine. Com. There is an expert goes by the name of rodbolt (I think) who seems to know more than anyone else I know of, but not sure if still active.

mhb100 · 22 July 2018, 14:32

What Psi are your cylinders giving?

mhb100 · 22 July 2018, 14:42

When you changed mystery filters how many did you change? and did you change the ones in the injectors?

mhb100 · 22 July 2018, 15:22

Had a quick look on some other posts. If your coils, hp psi, cylinder psi, and fuel regulator screen (in top of vst) are all good, and your 100% sure your on all 6 cylinders then perhaps best to get the injectors tested and cleaned. I expect your throttle adj and reeds are all OK but that's all I can think of.