HPDI INJECTOR QUESTION

[flounderpounder225]

2003 250 HPDI, History, bottom port side plug (#6 if I am correct) was fouling every few months, engine didn't like to idle on the hose, I suppose because with 2 Cylinders Already shut off at idle, a third not acting right made the engine die while trying to flush. WOT was ok, no surging or missing, but not getting my normal 5500-5600 rpm. Went through the secondary ignition, measured all the boots, and a few were at the top of the 4-6 ohm range so replaced them. Also noticed the #6 wire where it screws into the boot looked corroded inside, so I replaced that coil pack/wire, all new plugs and the engine screams, however; pulled #6 plug yesterday, after running for a while on the hose, the center porcelain on the electrode was wet with fuel oil mix, the other 5 plugs were dry and white/tan normal. Pulled compression on all cylinders and all were at 125 +\- a pound or two. So, I am thinking I may have an injector issue? I think the injector is firing, or the engine would not run as well as it does, but I think the injector may be leaking under pressure and constantly dripping fuel into the cylinder? Am I chasing the right dog here?

[seabob4]

Marc, you should have a schraeder valve on the fuel rail, get a fuel pressure tester and do a leak down test.  See if you are losing rest pressure...

[flounderpounder225]

I'll look at that Bob, but not sure if that is something you can do on an hpdi, not like our cars with that valve, my pressures at the final end are upwards of 800 pr 900 psi.  The only schrader valve I know of is on the VST can, and that is medium pressure, 60ish I think.

[seabob4]

Marc, those would be operating pressures.  No way is the system at that level going to maintain a rest pressure of 800 or higher.  Find out what the rest pressure is on the fuel rail, the FSM should give the specs...

[Blue Agave]

Can't help with your question, but based on the age of the motor pulling the injectors and having them cleaned is a good idea.  Although I was not experiencing problems I did mine and replaced the reeds as well, noticeable difference in performance and fuel consumption.

[dburr]

Was curious Marc what the injector type was because it seems to not be closing all the way.  I got this from a good THT post about HPDI filters.

Conclusion would be that either stray current is keeping it open, not sure how that could be possible because they are charged open with critical timing, or there is a micro booger in the seat. Either way it means "fun with injectors".

[flounderpounder225]

good pic, I am thinking just hanging open a little, Brucato In NC sounds like the place to go for repair on these, they have a very good rep on several forums, and they say the can adjust the injector?  I guess the pintle valve is adjustable looking at the picture.. Thanks

[dburr]

Can only guess here Marc based on previous life and experience with diesel injectors and those have all kinds of tweets that can be done. Depending on the actual injector type you can change nozzles, tips and seats and bore diameter of the injector guts to get more gas where you want it..

But all can get carbon in the nozzles and that in turn can work its way up into the seat and low load/low fuel pressure.

Good luck! 

[futch13]

Fuel Pressure at VST key on should be 45ish, when pump stops may bleed back down.  Running pressure at VST will stay the same, High pressure depending on model is 750+- or 1200+-.  The only way to measure high pressure is with a laptop. 

It sounds like a leaking injector.  If you send one out, send all of them out.

[flounderpounder225]

I'm going to buy the interface cable from Andy at SIM Yamaha, he said he would send me the software to install on my laptop, then send him the disc back. Also, new LP pumps, and he has a fuel pressure test kit with adapters that will be good for the VST pressure.  He explained a injector leak down procedure using the laptop.  So this weekend I think I will begin looking at getting the injectors out?  Just wondering if I could cycle the suspected injector for a second or two while shooting some sea foam through it, then pull the plugs and wind mill the engine to get the residual out, if there was something clogging the seat of the valve in the injector it might clear it? 

[dburr]

I worry about the tolerances.. Diesel injectors were tight, like .00001".. If the HPDI injector is the same way, be sure to use a cleaner that does not clean "dry", you want a film left behind so the guts have no chance of going metal to metal.  Best case is you win and she cleans up.. Worst case is you end up with it busted more then it is now and you out the +/- $70 for a new injector. 

If you do windmill with everything connected you are going to have a super explosive mist coming out of that nozzle so EXTREME care must be exercised.  The though of that gives me the heebeegeebees.. And I like things that go boom...

[flounderpounder225]

how about $300 +/- per injector?? 

[seabob4]

how about $300 +/- per injector?? 

Ah yes, Yam is VERY proud of their parts...

[futch13]

You can get them cleaned for $50 or less per injector.  They put new filter cans in them at the time.  http://www.mrinjector.us/   There was an Injector Doctor or some name like that on the East coast, NC or somewhere, and ProMarine in Bradenton cleans them also.

[dburr]

$300??

Holy SCHIZNIT!!!  I hopped onto ebay and got the number there.. For $300 I'd be tryin to clean them too!!