[ba] Coupe stopping intermittently,

audion at serversmiths.com audion at serversmiths.com
Mon May 17 14:57:21 EDT 2004

On Saturday, May 15, 2004, at 08:49 PM, Ti Kan wrote:

>> By the way does anyone know if the signal from the coil is just DC or
>> is it AC based on the coil firing?
> It's "AC", based on the ignition pulses.  The fuel pump relay has
> a pulse detection circuit in there that will turn off the pump if
> the pulses stop.

Well, I tested everything pretty thoroughly and either have a defective 
new relay (@ $60+) or the coil is not putting out enough voltage to 
trigger the circuit (which I doubt). I measured about .7 to .8 of a 
volt coming off the coil connector going through the relay to ground 
although it "seems" to show the full 12V+ of the system for a second 
and then drop to the .7 - .8 volts. With all of the other terminals 
connected up outboard of my relay panel (to make sure I'm getting the 
voltage to the ignition key 12V relay terminal etc.) I still get no 
voltage out to the #87 terminal to feed the pump.

Using a standard Bosch relay outboard of the relay panel gets 12V to 
the pump and the car runs fine. So, I'm inclined to cut my losses time 
and money-wise and try and rig up an alternate safety feature to shut 
off the pump if the engine is not running.

What are the other methods used by car makers to shut off the fuel pump 
if the engine is not firing? Is it always a signal from the coil to a 
custom fuel pump relay?

Any advice is greatly appreciated.



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