I have a 1998 Dodge Ram 1500 4x4, 5.2. One day I stopped and put gas in it, got back in and it fired up then died and would not start.[] Poured a little gas in the throttle body and it would run then die. Switched the fuel relay with one of the other relays in the box but still nothing from the fuel pump (checked to see if there was pressure at the tap on the fuel rail, there was none) so I assumed it was a fuel pump. After replacing the fuel pump it still does the same thing, there doesn't seem to be any power making it back to the fuel pump. Is there anything else that could be causing this besides a relay, does the pcm have anything to do with controlling the fuel pump?[:-]

 

I would think you have a bad Camshaft Position Sensor or a bad Crankshaft Position Sensor. You have checked all your fuses? If the PCM does not see certain signals from engine sensors it will shut down the ASD realy and you will loose power to the ignition and fuel system. Can you hear the pump run for about 2-3 seconds when you turn the key to "on". Can you have someone pull the error codes off the computer? you might want to get yourself a subscription for your truck at www.alldatadiy.com to get all the diagnostics and wiring diagrams. Real good info for $25

 

All of the fuses seem to be Ok, if you pour some gas in the TB it will run. You can't hear the pump run at all. I pulled the plug off the pump and hooked a volt meter to it but it doesn't show any voltage.

 

Well, that's some good news in a way. This means the Crank and Cam sensors are ok. Try to start it then shut the key off, then see if you can feel the fuel pump relay click when the key is turned back on, you'll need an assistant.

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Next wiring diagram.

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Double check 2 fuses. Fuse #3 in the PDC under the hood and Fuse #9 in the fuse block under the dash.

 

Rechecked the fuses, they are Ok. Pulled the plastic cover off the relay, when you turn the key on, it closes contacts then releases, then after you try starting it it closes and releases shortly after cranking.

 

Ok, then I guess the next thing to check is whether the relay is actually supplying voltage through the contacts. Have you had any other strange electrical problems with the truck recently?

 

No, it was running perfect, that's why I'm so puzzled by this.

 

Still sounds like a bad sensor, but what has me puzzled is that you cannot hear the pump run for 2 to 3 seconds when the key is turned on. Let's see if we can supply voltage directly to the pump and see if it runs. I'll have to work up a diagram