fuel temperature and regulator

[Shannen Durphey]

andy quaas wrote:
> 
> Can the temperature of gasoline affect the fuel pressure on a tbi
> system?  I have an in-tank pump (brand new).  I used to run 18 psi and
> the fuel pressure was stable in all weather.  Now, with the 7730 ECM i
> run 11 psi and it varies from 12 psi down to 10 (which makes a
> difference in performance).  I used to have an external electric fuel
> pump, and the pressure went from 14 psi down to 9.5 or so.  When its
> nice and cool outside (les than 65 degrees), its stable.  All filters
> are new and there are no leaks.  Could my pressure regulator (TBI
> mounted) be bad?  Should the temp. affect pressure?  Thanks in
> advance.  Also, is there anybody actively playing with a 7730 ECM?  I
> am about ready to purchase an eprom emulator and start on mine.
> 
> Andy Quaas
> 
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Well, I've seen several Fords vapor lock, but no Chevy TBI
engines.  But that doesn't mean temp isn't affecting
pressure.  It may not be affecting pressure directly,
though.  You might check to see if voltage at the pump
changes with temp. Maybe system voltage is slightly lower,
causing change.  Also, I've thought about using a power
steering fluid cooler from an Olds 98 (around 1989) in the
fuel line.  Might try that.  How about pinching off return
hose when warm to see if pump builds more pressure?  Try to
eliminate some variables.

Shannen