Volvo Maintenance Hints for 7xx/9xx - Bill Garland's Nuclear ...

Carburetted Engines. See the note regarding relays below. Don't immediately
conclude you need a rebuilt carburetor.
No or Slow Hot Start: Problem Diagnosis and Repair. See the attached file for a
quick-reference guide to no- or slow-hot-start problems and diagnoses.
No or Poor Cold Start: Problem Diagnosis and Repair. [Editor] Assuming you have
reviewed the checklist above and eliminated ignition or fuel injection components as
sources of a poor cold start condition, look for vacuum leaks. Holes in the air intake
hose, vacuum tubes, a failing vacuum check valve in the brake booster, a broken
booster diaphragm, or a leaking intake manifold gasket can all cause your engine to
fail to start or to perform very poorly once started, with fluctuating or high idle and poor
tickover.
Regina System No Start or Re-Start on Cold Mornings. [Tip from Bruce Young] If your
car has Regina fuel injection and you have difficulties with re-starting after the car has
been sitting for half an hour or so, see the Volvo TSB 23-135 from January, 1990
regarding Cold Start Problems. Here's a summary:
"Below 23°F (—5°C) cold start difficulties...rich fuel mixture during cold start crank and
warm-up"
Before chasing this down, you can tell if this TSP has been applied or not by checking
the wires at the cold start injector plug. First, peel back the rubber boot. If the 2
connected wires are Gray-Black and Blue-Green, the TSP has NOT been applied. If
the wires are Gray-Black and any other color (with Blue-Green cut off and taped back
-- or removed --) the TSB HAS BEEN applied. NOTE: This TSB rewiring will cause a
permanent 3-2-1 OBD code, but no CE Light.
Background: The CSI has voltage is applied from the Radio Suppression Relay, like
the regular injectors do. And is controlled on the ground side by the ECU, based on
temperature. The TSB changes the CSI's voltage source to an auxilliary terminal on
the starter solenoid. So the CSI now gets activated only during cold cranking, rather
than as soon as the key is turned on for that 1-2 second pump buzz — and all during
warm-up, till warmed above the "cold start" temp criteria.
Intermittent No Start or No Warm Restart: Radio Suppression, FI Relay, RPM