'86 4kq back to no start, CIS help please.

R Mangas porter_dog at hotmail.com
Tue Dec 17 22:18:41 EST 2002

   As you may remember my 'perfectly reliable' '86 4kq developed a stalling
problem last week.  It would start normally, then stall right away when the
CSV shut down.  I checked the fuel pump delivery rate (great), the system
pressure (normal), and the differential pressure (exactly the same as the
system pressure, should have been 3-7 psi below).

  Because it was convienient to do so, I swapped in the differential
pressure regulator from my '87 and 'solved' the problem for 150 miles.  This
came to an abrupt end when I tried to leave work to drive home yesterday.

  The current problem is a _total_ non-start; it won't even TRY to fire, not
even a little bit.  Today I verified compression (good) and spark (fine).
Checked system pressure (same as before, 79.5 psi; in spec) and differential
pressure and found it to be 79.5 psi...  Resistance of the differential
pressure regulator is fine.

   The next test is to check the return volume from 'the lower chamber of
the fuel distributor'.  There are two hardlines coming off the fuel dist;
which one is it?  I'd guess the smaller, as the expected flow rate is low.

   This test should implicate either the differential pressure regulator or
the fuel distributor.  Since the DPR swap seemed to cure the problem last
time ([un]happy coincidence?) I sort of suspect that might be the problem
now.  What underlying condition would fail two DPR's in quick succession?

   I don't know enough about CIS to figure that out, and I'm in a bit of a
spot.  It's parked in staff parking in the office building my company is in,
which will be fine for a couple days but too much longer and there might be
some frowning going on.  Also, I'm moving in two weeks and don't have a lot
of free time to devote to a suddenly unreliable car.  If I can't get this
sorted and kind of quickly, I'll be forced to scrap it :(

  I've never done the t-belt, no idea when it was done either- is there a
quick way to verify cam timing?

  What about the damp-ecu syndrome- is there a quick way to check for that?
Will the normal start/cold enrichment checks verify ecu function adequately?

  Thanks for any insight,

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