fuel pump

[daking]

I've been putting this truck back together now for sometime. 

 

The engine electrical in mostly done and connected. I'm missing an O2 and Crank sensor. The O2, has been relocated and I need to extend the harness, and I had the incorrect crank sensor. 

 

I pulled the MJ sending unit from the tank. I put the XJ pump and XJ fuel gauge sending unit on the MJ pump mount.

 

I recently finished the main power on the MJ, Battery and feeds. 

 

I turned the key, for testing. I hear the fuel pump for about ~2 sec, but get no fuel pressure. Disconnected the hoses and no fuel flow.

 

I've read in passing, that the ECU will shut the fuel pump off if the crank sensor is disconnected. Is that true?

 

 I'll have all the sensors connected this weekend, and try again. Just trying to figure out why I have no fuel pressure. 

[HOrnbrod]

What is it? Renix, HO, OBD1 or 2?
 
Depending on your year, it's probably the ASD relay unlatching.
 
From a previous post:
 

Which relay did you bypass? The fuel pump relay or the ASD (auto shutdown) relay? Both have to be latched for starting. When starting the engine the ASD relay latches and looks for the distributor to spin. If not, the ASD relay trips and cuts power to the + coil and the fuel pump. You can test the ASD relay by running +12V from the battery directly to the coil pos terminal. This will also backfeed 12V to the fuel pump through the ASD circuit. If the pump runs, the ASD relay is bad. If not, the pump itself, fuel pump relay, or the wiring is fubar.

 
http://www.allpar.com/fix/codes/sensors/auto-shutdown.html

[gogmorgo]

As an aside, when you extend the O2 sensor's harness, don't just cut and splice the wires. Pick up a proper 02 sensor extension harness. The O2 sensor needs to read atmospheric O2 levels so it can compare the two, and it gets to atmo through the insulation in the wires. If you cut and splice, you'll block off this access. Can't really help with your fuel pump issue, though.