Re: [ihc] RE: Relaying George's power

[John Hofstetter <hofs@xxxxxxxxxxxx>]

On Jul 24, 2004, at 11:54 AM, George B Humphrey wrote:

> John and Jim,
> 	I think I am understanding this. First of all, yes, I do have a Ford
> solenoid.
>
> 	The Bosch relay has two trigger inputs? One triggers during cranking 
> and
> one triggers during run? The run trigger will also prime the fuel pump
> before cranking, correct?
Well, not exactly. First of all, I'm not sure what you mean by "has two 
trigger inputs". If you mean that the relay needs to be triggered in 
both start and run, then yes it has two trigger inputs, but that 
trigger comes from the + side of the coil, so just one wire. SEE PINK 
WIRE BELOW.

The Bosch relay only does one thing, send power to the red lead on the 
ECU. The ECU controls the fuel pump, the fast idle solenoid, 
everything. So we need to have the relay activated when the ignition is 
in either the run or the start mode.

> 	Something I don't understand. Aren't both sides of the Ford solenoid, 
> in
> a sense, hot? It Just takes the ignition switch to complete the 
> circuit.
> If I attach a trigger wire to the side that runs to the Delco solenoid,
> it completes a circuit; Battery- solenoid- relay-ground. Wouldn't this 
> be
> the same as connecting the trigger wire to the battery?
No, the side of the Ford that has the lead to the Delco is powered only 
when the key is in the start mode. If you connected the trigger wire to 
the battery the ECU and all that it controls would always be on.

> 	I also wonder about the resistance wire. If it is only used during
> running, why didn't the fuel pump prime when I tried to use the coil 
> as a
> trigger? I got nothing in run or crank.
When you turn on the ignition the fuel pump should run for 8 to 10 
seconds and then the ECU turns it off for safety's sake. (long story) 
THE ECU TURNED IT ON, not the relay or anything else. If it doesn't go 
on, then the ECU is not getting enough voltage, or you have a weak 
ground, or the unit is wired wrong, or .......

You need to turn on the key and check the voltage between ground and 
the connection to the red lead from the ECU. It needs to be battery 
voltage. Then check the voltage at the same place while cranking, it 
MUST be above 8.5 volts, or the ECU will not function, including 
telling the fuel pump to pump. Also check the voltage between the pink 
lead and ground, it must be above 8.0 volts during cranking.

As I read the trouble shooting guide, I am reminded about the pink 
wire. It needs to go the Delco side of your Ford solenoid. THAT IS 
WHERE THE SIGNAL TO THE ECU COMES FROM DURING CRANKING.

If that pink wire is hooked to the right spot, then I think the + 
terminal on the coil will work for you to activate the Bosch relay and 
power the red lead.

If the fuel pump doesn't come on for the 8 seconds, then you need to 
check for voltage between the + side of the pump and ground. There  
should always be voltage here when the key is on,  as control of the 
pump is through control of the ground.

If there is voltage here, then remove the green wire from the pump and 
ground it, the pump should go on. If the pump doesn't come on, then you 
need to check for continuity from the pump to the ECU.

John

>
John Hofstetter
Ol' Saline
www.goldrush.com/~hofs