[Vwdiesel] starting problem testing injectors

Area31 Research Facility stephensrw at stn.net
Fri Mar 10 07:26:25 EST 2006

I don't have a lot of experience with diesels yet but what I have learned so
far with the VW's is that IMO injector troubles are more prone to cause bad
knocking, hammering noises in the engine when running, and roughness making
power.  If you have a normal sounding engine once warmed up the problem
probably isn't injectors.

I have a 1980, 1.5 NA in a genset I made for my estate for backup power in a
blackout, and to provide auxiliary heat in the workkshop from co-gen.  This
engine needed to have O2 injected from a welding torch in the air intake to
start.  Once running it is excellent.  I finally solved the nearly
impossible starting by putting a 6 volt golf cart battery in series with the
normal 12 volt starting battery. Before I'd drain a battery flat and the
starter would be literally smoking to get the engine to start.  That was
horrible starter abuse.  Now on 18 volts it spins like crazy for maybe 5
seconds and starts every time. Not really abusing the starter anymore
despite the overvoltage.  I suspect my starting problem is the old FI pump.
The engine really stumbled once first started if I pushed in the start
advance before it had run for a minute or so.  I just had the back
distribution block pulled out of the pump far enough to change the O-ring
and noticed a bunch of black powder, probably metal shavings came out of the
pump cavity when it drained into a can.  Since it has been put back
together, minus this crap, it has been running much better right after
ingition and I can now go quickly to pushing the advance in without stumble.
This is an interesting bit of info I guess.  I can see how there would
really be no-way for the heavy metal dust to pass through the pump and it's
presence would exacerbate internal wear and pump problems.

I don't have a injector pressuren tester made yet but have tested injectors
by hooking one up to one of the FI ports out of the head and watching the
spray pattern into the air with the engine running on 3 cylinders at idle.
Don't breath this mist or hold any part of your skin it it's path!  You can
clearly identify a bad injector this way once you've seen the spray pattern
from a known good one.


----- Original Message -----
From: "paul lew" <biovolks at yahoo.com>
To: <vwdiesel at vwfans.com>
Sent: Thursday, March 09, 2006 3:59 PM
Subject: [Vwdiesel] starting problem testing injectors

> Hi
>   Me again
>   Does anyone have a way of testing/inspecting the injectors without the
pressure machine mentioned in the book, or taking them somewhere, as this is
my only transportation ,so when the're pulled, i'm not drivin.
>   There's one thing I'm thinking about trying...
>   If the cylinder compression is low when cranking ,then the exhaust
threoretically should be too, so I'm going to check what kind of pressure
comes out when cold trouble starting ,then when it's running and hot,
disconnect the fuel pump solenoid lead and compare pressure.
>   I'll also compare the air intake this way.
>   Hopefully it will tell me something about overall compression.
>   exercise in futility??? thoughts???
>   Paul
>   British Columbia
>   Canada
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