HPDI Injector ? for Rodbolt/anyone

[boscoe99]

Is an HPDI injector supplied with continuous voltage all of the time with a ground then being applied to actuate the injector or is it grounded all of the time with voltage being applied to make it function?

Have you ever measured the injector terminals to see if there is any connectivity to the body of the injector?

[99yam40]

wasn't there a thread on injectors not long ago about all 6 being shorted.

lots of discussion in that one that might help
but I do not remember if the motor was HPDI or not

I looked back and it was a HPDI.
Looking at a drawing on that thread, injector is spring loaded closed so have to energize to open.
No clue if the driver would keep 90 volts on it all the time and then ground to activate


http://www.yamahaoutboardparts.com/f...s-th27128.html

[boscoe99]

wasn't there a thread on injectors not long ago about all 6 being shorted.

lots of discussion in that one that might help
but I do not remember if the motor was HPDI or not

I looked back and it was a HPDI.
Looking at a drawing on that thread, injector is spring loaded closed so have to energize to open.
No clue if the driver would keep 90 volts on it all the time and then ground to activate


http://www.yamahaoutboardparts.com/f...s-th27128.html

Yes. And I now think this thread and the other one are some how related.

[pstephens46]

I expect he will weigh in once coffee is ready in the am.

[rodbolt17]

the only time I have ever seen a voltage is when cranking or running it.

typically 85-95V peak.

never seen one short to the body but I guess it would be possible.

I have seen a handful open circuited and more than one stuck.

[boscoe99]

I am presuming that a ground is applied to actuate the injector similar to most Yam stuff. Do you agree?

[rodbolt17]

I doubt it.
the only way you could get a 90V peak using 12V is by using a step up transformer with transistor switchs and a capacitor.

as HPDI cannot group inject that would mean 6 transformers and transistors.
it is going to be a very rapid rise and fall on that 90V.
in the millisecond range.
to make 90V continuous would generate a tremendous amount of heat.

[99yam40]

That makes sense.

Bosco is this question coming from a different forum or a PM to you?

[boscoe99]

I doubt it.
the only way you could get a 90V peak using 12V is by using a step up transformer with transistor switchs and a capacitor.

as HPDI cannot group inject that would mean 6 transformers and transistors.
it is going to be a very rapid rise and fall on that 90V.
in the millisecond range.
to make 90V continuous would generate a tremendous amount of heat.

Resistance value of the injector is nominally 1 ohm. 90 volts across 1 ohm is 90 amperes. A hellava lot of current. Certainly more than the wire is rated for. I suppose the current flow is so brief that the wire cannot heat up.

I am suspicious of 90 volts continuous being applied because of the reason that if and when an injector coil shorted to ground (which has been reported) there would be lots of smoke seen in the area.

I am now wondering if the two wires for each injector have their ground and voltage applied at the same time. Something I will probably never know.

[boscoe99]

That makes sense.

Bosco is this question coming from a different forum or a PM to you?

Message came to me as a PM from a different forum. From a fuel injector repair man. Seems to be based on the injectors that were the subject of the other thread that you referred us to. In which I participated but forgot about until you reminded me of it.

[99yam40]

I am suspicious of 90 volts continuous being applied because of the reason that if and when an injector coil shorted to ground (which has been reported) there would be lots of smoke seen in the area.

I am now wondering if the two wires for each injector have their ground and voltage applied at the same time. Something I will probably never know.

As Rod posted to create the 90v continuously would cause lots of heat in each cylinders driver.
even when that cylinder was not being fired.
But they do hit a lot of times per sec especially at high RPMs, only drawing current part of the time when injector is energized

Is there a wiring diagram showing the 2 wires to injector and where they come from or go to?
If one is to a ground or can be measure as a continuous ground that may answer the ground part of the question

[rodbolt17]

never looked at it cause it is rather irrelavent in troubleshooting but my guess would be to leave the ground path and trigger the driver.
they don't show circuit diagrams of the driver in any manual.
not so sure I could properly trace the pulser signal to driver trigger circuits through the driver anymore.
back about 1990 would have been a breeze.

back in the day we had to track signals by the diagram through the various And gates,Not gates and phatom Or gates.
plus all the various transistor,diaodes SCR's Igfets,Mosfets and what have you.
start at the on button all the way through the search/track processors.

don't know that I could do it now.

gotta remember we monitored the CIWS back then with a TRS 80 then a Compac 280 with DOS 6 YEA.

[99yam40]

I always left all of the electronic circuits to the guys that were trained on that stuff.
My brother was in a Meter and relay shop in the plant.
They had an inside group that repaired electronics.
I still call the only one I know left in there for special stuff when I need help.
Like the elevator controls at the Church I attend and am on the board of properties.
Saved a lot of $ having some boards repaired instead of buying new.

Still think ohm meter should tell if ground is constant without having to dig into circuits too deep

[boscoe99]

As Rod posted to create the 90v continuously would cause lots of heat in each cylinders driver.
even when that cylinder was not being fired.
But they do hit a lot of times per sec especially at high RPMs, only drawing current part of the time when injector is energized

Is there a wiring diagram showing the 2 wires to injector and where they come from or go to?
If one is to a ground or can be measure as a continuous ground that may answer the ground part of the question

There is a wiring diagram but it is hard to follow. Six wires coming from an injector driver, two wires per injector. Two total injector drivers for six injectors. All of the wires have separate wire colours. Injector drivers are con*****ed by the ECU. None of the injectors wires appear to go to a common ground or a common power supply. Unlike other Yamaha models wherein the injectors share a common power supply with the ground wire being con*****ed by the ECU.

My head hurts.

[99yam40]

ohm meter at injector end of harness maybe