OK posted this in the not so emergency forum...But it is becoming one.
Eng will quit esp at almost idle and pointed down a grade or up.
When this happens it is sometimes just a brief miss keeps on going but the LP pressure has fallen to 0. Other times all keeps on after the glitch ( and pressure will not fall off).
Other times Eng just quits, But always immediately restarts. ( never a problem)
I am guessing a open in the power side of the ECM
Please help.
I have pulled all connections and re snug them. Checked everything I can think of.
The Restart confuses me

 

Possible fuel pump relay in PDC try swapping with another relay.

 

Ok thanks, is that under the hood in the box...right ?

 

So if this falls off line ..eng would quit ? Or just the L.P.?

 

The Engine Control Module (ECM) energizes the electric fuel injection pump through the fuel injection pump relay. Battery voltage is applied to the fuel injection pump relay at all times. When the key is turned ON, the relay is energized when a 12 - volt signal is provided by the ECM. When energized, 12 - volts is supplied to the Fuel Pump Control Module. The Fuel Pump Control Module is located on the top of the fuel injection pump and is non-servicable.

The fuel injection pump relay is located in the Power Distribution Center (PDC) Refer to label under PDC cover for relay location.

 

Again , it is the restart that baffles me
On the restart...It must bypass the problem area and by that time all reconnects itself....?
I just don't get it if the voltage come strictly from the ECm...
Seems like the L.P. sees start voltage from a different source ..Once the ign switch is in the run position my medley sings my bad tune

 

OK On further drunken thought here....does anyone have a schematic of L.P. and power to ECM ?
I think if I try a HOT wire to the L.P 1st
Then a Hot wire to the ECM If one of these fixes the problem..................

 

Up Date, - I Hot wired the L.P. and provided a extra GRD.

Now the Eng will die intimately and it catches itself every time cause the lift pump stays on line no mater what.
So some clues, When this happens the lift pump used to sometimes go off line ..In real life what would cause that, ? A interruption in the circuit to the ECM ?
Seems to happen in a slow right hand turn more then anywhere else
Ign switch ?
Help, pullin my hair out here
thanx in advance

 

Bigiron70,
Do the relay(s) hold the EcM on line ? Or is that a start deal ?
If the Ecm goes off line for a second would it be normal for it to stop PWR to the L.P. ?
I am just trying to dial in this open to the ECM or intermittent signal to the ECM
Thanx

 

Will anyone please come up with a wire scamatic how this thing is put to gather?
Where does the ECM pick up power from ? ( I want to by pass this)
My problem is a loose connection some where between the Bat, Ignition switch, and the ECM .

 

Everyone give up ?

 

OK found a dude with a code reader P1689 No communication between ECM and pump
What next ?
Of course this is a intermittent problem ..I jiggle wires stand on my head...ECT

BUT does this make it a loose connection just between pump and ECM ?
( that's a short distance)

 

P1689 diag procedure, hope this helps

 

Load test the injection pump power and ground at the injection pump connector using a head light as a load.
Case Number 910614340
Vehicle Issue No Power. Mil On. Code P1689. Check Injection Pump Operation;Use the powertrain diagnostic manual and perform diagnostics for code p1689 Check the fuel transfer pump operation. Reference TSB 14-002-03. When code p1689 is setting load test the injection pump power and ground at the injection pump connector using a head light as a load.
System or Component Lack of Power / Sluggish;Customer Concern (No DTCs),DTC / Error Message;Malfunction Indicator Light / MIL / Check Engine Light,Injection Pump,Group 18 - Vehicle Performance / Driveability;Yes - Intermittent,Yes - Continuously
Recommendation If the injection pump power and ground is ok, no wiring problems are found doing the p1689 diagnostic test and fuel supply is ok replace the injection pump.

Modification Date 06/23/03 8:40 AM

 

Thanx Big Iron.
Will try to decipher the head lt routine, maybe pull all conections and reinspect for a loose pin