Re: [DML] fuel pressure problems

["B Benson" <delornut@xxxx>]

The vacuum line from the rear of the drivers side of the intake manifold
goes under the manifold to the center orifice of the thermo control valve.
The line coming from the thermo control valve's right side orifice goes to
the pressure control unit. It splits into two hoses prior to hooking to that
unit. One hose supplies vacuum to the top side of the control unit and the
other, through a delay valve [ black half faces the line going into the
unit ] which momentarily delays the vacuum supply to the bottom half of the
control unit. This gives a rich 'spike' to the engine during acceleration
while the engine is still cold. The third hose coming from the left orifice
of the thermo control valve goes to the distributor advance solenoid. When
the engine is cold the valve supplies vacuum to the control pressure
regulator and when the engine warms up the valve shifts and supplies vacuum
to the distributor advance system. In other words there's vacuum at the
control pressure regulator when the engine is cold, not when it's warmed up.
There is no vacuum to the distributor advance solenoid when the engine is
cold, there is when it's warmed up. That should be easy to check.. You can't
see the thermo control valve without removing the manifold so the only other
way to check is by feel. There's not much room under the intake so if you
have big hands it's tough to do. Some cars came from the factory hooked up
wrong but there's no way they wouldn't have been made right by now. Anyhow,
make sure the vacuum lines are correct before you spend time tracking other
possible problems.

Bruce Benson



> When I fixed the wires to the fuel pressure regulator and hooked the
vaccuum
> hoses back up, the engine ran richer. I've been turning and turning the
CO
> screw closed, but when it reaches a point where it's not spewing black
smoke
> anymore, the car will not idle or run at all below 4000RPM.
>
> I can not 'take it out for a drive'... the engine does not run well enough
> by itself...
>
> Is there a way I can ensure the spark advance is working/getting vaccuum?
> Besides checking timing- of course... I'm pretty sure my timing plate is
not
> stock, and am unsure of it's usefulness...