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>From: Douglas Henry <dhenry@u.washington.edu>
[forwarded to the group so everyone can see it]
>I saw your earlier post on injector storage. I have four that I picked up
>used that I keep as emergency spares. I've never cleaned them up or
>anything. Would you recommend cleaning them up before using the light oil
>storage technique that you listed?
I've never seen any improvement from cleaning. The really important thing
is to keep them from rusting. Ones that have been stored for a long time
without any particular attention to rust prevention may already be ruined.
Put oil in/on them, wrap them in some of that brown corrosion prevention
paper, seal them in ziplock bags.
Two things happen to the old ones. Rust and the o-rings shrink causing
leaks. Sometimes installing them, and letting the o-ring sit exposed to gas
for awhile will cause the o-ring to swell up and reseal, but don't count on it.
Something I've been meaning to mention is that rust can form in the
injectors of cars that have been stored just over the winter. I had a
customer who couldn't get his D-Jetronic Type IV started in the spring. I
spent a long time checking everything out and finally, in desperation,
disabled the fuel pump to see if perhaps it was flooded. Well, after
cranking awhile it sputtered to life.
Once the idle settled down, thinking the flooding was cleared, I enabled the
fuel pump, and the car promptly died! So I started over: pump off, crank
engine, start engine, wait for idle to run smooth them start to stumble,
turn on pump, engine dies again???
Now at this point I was pretty confused, but it was clear that the car was
getting too much gas when I just turned the pump on. Since I still had a
pressure gauge connected to the gas lines I decided to try to turn the pump
on and off by hand while watching the pressure and listening to the engine.
Okay, by now I know the drill. Get her started, wait for the idle to
stumble then just goose the pressure up to 5 psi, then 10; it runs better at
5, so I let it drop. All the time the the pressure is rising and falling as
the pump is on or off I can sense when the engine is happy, so I try to keep
the pressure in the "sweet spot," all on the fly by hand.
After about a minute the sweet spot has crept up to 12-15 psi; two minutes,
20 psi; 3 minutes, 25 psi; and 4 minutes, 29 psi and regulating. All is well.
We need to understand that I have no way of absolutely knowing what was
happening during this time, but I suspect that there was something in the
injectors that was keeping them open longer than the brain was requesting.
Perhaps they were gummed up; perhaps there was rust on the sliding parts of
the valve. I don't really know, but I HAD already pulled a couple of them
out and watched the spray pattern, and they were fine.
My conclusion: Something was keeping the valves open longer than the
electrical signals required. Just watching the spray pattern, I can't tell
if they shut off in 10 ms or 40 ms. Whatever the problem was, it went away
with the mechanical motion, and possibly the solvent action of the gasoline.
Just food for thought.
Jim
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Melissa Kepner Jim Adney
jadney@vwtype3.org jadney@vwtype3.org
Laura Kepner-Adney
Madison, Wisconsin
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