no, it was directly connected (un-fused) to the battery of another car. My jumpier wires were just shy to reach from my battery to the pump. I was trying to eliminate a faulty pump exchange.

What are you thinking?? Did damage something in the other car, or my new pump?

 

By ran like nothing was wrong do you mean you now have 45 PSI pressure?

 

Ran perfectly only when pump was connected directly to battery, bypassing the relay, wiring, pcm........

 

Battey + - direct to fuel pump 1 & 4 pin, full 45-50 psi and van instantly starts and runs perfectly.

Connected the fuel pump back to the connector that runs to the fuel pump relay, pressure drops back down to 10-20 psi and no-start.

if the pins in the relay are jumpiered to run the fuel pump, pump runs intermittently,

if the pins in the relay are jumpiered with just the hot wire and a separate ground source to the pump, will run continuously but not enough voltage to achieve the 45psi in the rail, no start.

 

Now there is no voltage to fuel pump.

The odometer on-off-on-off-on key code is showing "no buS"

What is that, I don't see it in my book.

Don't look good.

 

9 out of 10 times that means the PCM is no good. For the 1 out of 10 times it's a loss of power to the PCM (blown fuse?) causing it.

 

Well, this is for the 1 out of 10 times, one of the big 3 pcm plugs was unplugged.

When I was checking the pcm connections, one was not firmly seated and fell out causing the odometer flash the "no buS" signal. When it was plugged back in, the "no buS" disappeared and the mileage came back.

I still haven't located the voltage drop issue from the relay to the tank. I have checked across the connections and from the firewall to the tank. Next I'm thinking of working my way through the fuse box. Just not quite sure how to proceed through past it with out more understanding of wiring diagrams, troubleshooting tools and techniques. I thought replacing a standard differential with a trac-loc was difficult, but this electrical troubleshooting is complicated.

Tonight I spliced a wire from the battery pos. to the g/w fuel pump pos. wire with an inline 20 amp fuse. I left the fuel pump relay connected. The presure at the fuel rail has the 45-50 psi. and was able to drive it home with no issues. To turn the fuel pump off, I just pull the fuse.

Appreciate all the help. Fortunately, I have a back up work vehicle and can let it sit until this is worked through.

 

Ended up just installing a toggle switch on the dash to manually turn the pump on and off and has been working fine since with no issues with the exception when I forgot to turn the pump off.