Re: Hard-starting 1991 100s

[Eric Maxon <emaxon@megsinet.net>]

Never rule out vaccuum leaks as the culprit-- When the car's hot, you
don't get the 80-150ma diff p reg current, and the cold start injector
only sprays for a brief second-- even a small vaccuum leak will have a
much greater effect on starting a hot motor.  I've found 3 NF engined
cars with the SAME leak-- very difficult to spot, usually easy to HEAR--
the L shaped 1/2" dia hose connecting the idle air regulator to the
intake manifold.  It usually splits or pinches shut along the long seam
UNDER the fold of the manifold.  Listen for hissing from that vicinity
and peek between the manifold runners to see if it's squashed flat w/
the engine running.  Come to think of it, that's the only serious
vaccuum leak I've found on 100's-- I guess the 100 fleet is still pretty
new by rubber rotting standards.  This hose is only about $17 list at
the dealership.

That's my 2c.

Eric.

Phil Payne wrote:
> 
> In message <374424C5.36D8A820@nais.com> Michael Murphy writes:
> 
> > Good speculating Phil.  And the culprit (on my 89 100 with same problem
> > as Vic's) was the fuel pressure check valve.
> 
> Well, that's the next step.  It could also be the cold start valve, any
> of the injectors or the differential pressure regulator.  'System-side'
> problems like this are only rarely fast-acting, but sods to catch when
> they are.  'Control-side' problems are more common, but they're caught
> by the standard diagnostics.
> 
> If it's _this_ fast, BTW, the fuel pressure accumulator is probably
> also shot.
> 
> --
> Phil Payne

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