SPICA fuel pressure light

[James Montebello <jamesm@domain.elided>]

There have been a lot of messages on this, with plenty of good advice on 
the usual causes (clogged fuel filter, dead fuel pump).  I have an 
"unusual" cause, which may help someone else later...

My fuel pressure light would blink on for a few seconds several times when 
cold, esp. if the outside temp. was cool (below 60dF, say).  It would 
usually stay out once the car was warmed up.  This was puzzling, but 
ignored for awhile.  The fuel filters were almost new, I could hear 
the pump running, and the car was running fine.

Later, I heard the faint squeal of V-belt slip as the weather got colder.  
I had recently installed a voltmeter, and I noticed that the voltage was
stuck at 12v when I heard slip, and jumped up to 13.5-14v when I didn't.  
The fuel pressure light would only blink on when the voltage was stuck at
12v, and stayed out when it rose to the normal charging value.

The usual oil leaks at the front of the engine had lubricated the V-belt
enough that the alternator wasn't being spun at full speed until
everything warmed up enough to overcome the slipping.  The fuel pump was
running all the time, but not at full tilt while the voltage was low.  
Cleaning the pulleys and belt fixed the problem short-term.  The rest will
wait until the oil leaks are taken care of.  A lot cheaper than a new fuel 
filter, or a new fuel pump.

So, if your fuel pressure light is blinking on, and you hear the pump 
running, check the voltage before buying new fuel filters.

Interestingly, even though it was obvious that the water pump was also not
spinning at full speed, the car never got hot.  Indeed, this particular
car (the Berlina) never gets hotter than about 160dF (independently
verified with a thermistor), despite the recent addition of a 180dF
thermostat.  None of the usual signs of overheating.

james montebello
'84 gtv6
'74 berlina

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