Gordon wrote in
m:

How do you know when you have a bad injector and how do you figure
out which one it is?
Gordon


YouTube is your friend!
http://www.youtube.com/results?
search_type=&search_query=diesel+injector+testing& aq=5&oq=diesel+injec

How NOT to test injectors:
http://www.youtube.com/watch?v=_gUB81VfK40

Bad spray pattern from crap in the injector will make one cylinder knock
really loud. There's ALWAYS one injector that knocks louder than the
rest and that's just "normal". Same thing is true if the metering
circuit doesn't close right, bad springs, etc. That cylinder pulls lots
harder than the others from the supercharge of fuel.

A clogged injector simply has no fuel spray so the cylinder either never
fires at all and the engine goes on "humping" past the dead cylinder's
compression stroke never having a power stroke or the engine runs like
crap because that cylinder isn't pulling its share of the load,
virtually putting the engine in idle when it's the bad cylinder's turn
to fire.

Testing is pretty easy. All this runs on very high pressure, but very
tiny amounts of fuel. With the engine running under load, underway,
simply take an appropriately sized wrench and crack open the fuel
supply fitting to each injector, one at a time, while listening to the
results as you add yet another cylinder that isn't firing. When you
come to the one that's not firing or is overfiring, when you crack its
fuel line the engine runs the same....or that awful knocking from too
much fuel stops. When you open the good injectors, adding to the
problem, the engine runs much worse, now that it has two cylinders dead
instead of just one.....

When you think you've got it, shut her down and swap that injector with
a spare I just KNOW you have in your spares locker, right? You DO have
a calibrated torque wrench and know how to use it so you can set the
torque on the nuts correctly, right? No? Get one. Harbor Freight's
cheap Chinese torque wrenches are amazingly close to correct....closer
than the Snap-On ones we tested for lots more money.

If that fixes it, you found it. If nothing changes, you'll know we have
injector pump problems you can't fix at sea.

BTW, Harbor Freight also has fuel injector testers, the kind you attach
to the injector then pump by hand so you can see the spray pattern of
fuel coming out of them....very handy for testing injectors.

What make/model of engine are we testing, anyways?? Doxfords wouldn't
use this kind of test:
http://www.youtube.com/results?searc...y=doxford&aq=f



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Larry
You can tell there's very intelligent life in the Universe
because none of them have ever tried to contact us.....