Engine/Transmission (1998.5 - 2002) Doesnt run

[fnny6770]

I bought a new Airtex fuel pump for my 01 ram 3500 diesel, it still had the factory pump on the block, the new pump came with a plug that plugs right into the same place that the factory pump does, I wired the new pump so that the power to the pump is fed through a relay, the relay is energized by the factory pumps plug that should energize in place of the factory pump, I turned on the ignition and the pump wont run, I checked for power to the relay from the factory pump plug, there is only about 8 or 9 volts, there is power to the relay contacts through a fuse so I know the fuse is fine and the hot wire from the fuse to the relay has power, just dont think the relays coil is getting power, My question is, does the factory block mounted fuel pump get both positive and negative power through the factory pump plug? if so, where does the power to the plug come from? In the junction box under the hood is a fuel system relay, does the power for the pump come from this relay? I can hear the fuel system relay being energized, I would like to know where the factory pumps power comes from, from start to finish. The new pump came with mounting studs that would have allowed me to mount it in place of the factory pump, and it plugs right into the factory plug, but I mounted the pump on the frame, and ran the wires up to a relay,

 

[Bob4x4]

The oem wire is fed from the ecm.It is not going to stay hot unless the truck is running.If you bump the key to the start position leaving it in the run position it will be hot for approximately 30 seconds.
Remember when you open up the supply line you may need to bleed the system.Never crank the engine over for more than 30 seconds or you risk melting down the starter,allow it to cool between atempts

 

[fnny6770]

I tried bumping the starter, still there's no power to the pump relay.

 

[SnoKing]

I ran an Airtex pump directly from the OEM lead moved and maybe extended (can't remember) to the frame for years without a problem. SnoKing

 

[Bob4x4]

There is no relay factory installed for the fuel pump.You need to trace the relay wiring to answer your question.The ecm output to the pump is pulse width modulated a standard volt meter will not show you what is going on-only an average.

 

[petersonj]

I would like to know where the factory pumps power comes from, from start to finish.

This wiring diagram is for a 2002, but I think it is the same for yours. Note the 18 gauge yellow wire with a white tracer that connects to the fuel transfer pump. This wire supplies 12 volts from the ECM - for approximately 1 second when the ignition key is switched on, and for approximately 20 seconds when the ignition key is switched to crank (bumping the starter).

- John

 

[fnny6770]

Found the problem, it was a bad ground, it works now thank You for your help