[DML] Re: not running

["content22207" <brobertson@xxxxxxxxxxxx>]

You'll probably get 1,000 replies to this one....

FYI: The fuel pump does not receive 12v until the engine is turning
operating RPM's (anyone know exactly how many?). There's usually, but
not always (in my vehicle at least), a short burst of current when the
car is first energized, but that's it. The RPM relay waits until the
engine is running to turn the pump on. It's a safety measure.

A device in the middle of the frame called an accumulator holds
pressure in the fuel system until the RPM relay kicks in. Accumulators
do go bad. Replacement isn't too difficult. A good indicator of a
failed accumulator is inability to restart the engine after warmup.
Cold, the engine can start from the cold start injector, but that
device does not operate when the engine is warm (unless you force it
to operate by switching its electrical connector with the CPR's
connector).

Jumping the RPM relay is quite simple. Locate the relay in the
"chamber of horrors" (relay compartment above the battery). It is
closest to the rear window, under the door lock module -- Number 34 on
the diagram on page M:07:02 of the Workshop Manual. Every one I've
ever seen has a green housing, but there may be other colors out
there. Pull the harness connector loose and jump from brown to
white/purple (opposite corners of the harness connector). The pump
should start to run, irrespective of any key position. WORD OF
CAUTION: this will eventually drain your battery if left jumpered.
After you're finished driving the car, remove the jumper. There is of
course no threat while the alternator is turning. What you've done is
jump from an always live wire (brown) to the fuel pump (white/purple).

When you're checking fuel pump voltage, be sure to use a known good
ground. The black/purple wire from the pump does not go straight to
ground, but passes through another safety feature called the inertia
switch (located in the driver's footwell). If this switch gets raised,
or otherwise loses its connection to ground, the pump will not spin.
The purpose of the inertia switch is to turn the pump off if vehicle
flips.

The fuel pump circuit can be found on Page D:04:06 of the Workshop Manual.

Double check fuse #7 while you're in the chamber. And remember that a
good fuse does not ensure a good circuit (the connector in the fuse
block may be pushed out, for example). If you've got 12v on the brown
wire connected to the RPM relay, your fuse and wiring thereafter are OK.

Regarding the "network of great guys," you are correct. Delorean
owners are some of the nicest people you will ever meet. The cars are
certainly neat machines, but the best thing about them is the people
they bring you into contact with. I recommend attending a group
gathering within driving distance (if you don't feel comfortable
driving your Delo, take another vehicle -- you'll be just as welcome).
Not only will you make new friends, but you'll have a chance to pick
up technical pointers in person.

Bill Robertson
#5939

>--- In dmcnews@xxxxxxxxxxxxxxx, "andy" <andyblackmon@...> wrote:
>
> Ok group I need some input. I am not getting 12 volts to my fuel pump.I 
> am sure that in all the books and manuals I own I can find the answer 
> to this, but we have a network of great guys who knows this by heart. 
> When I pour a little gas in the engine it runs till the gas is gone, as 
> I said not juice to the fuel pump. None of the fuses appear to be shot 
> (none are) and there is nothing loose at the pump. I recall something 
> about jumping the rmp relay but dont recall what or how, i need advice.
> 
> Thank you, 
> Andy Balckmon
>




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