ok my dad has a 95 ram 1500 and he told me he needed a new fuel pump put in. The engine would crank but wouldn't fire if u spray starting fluid it will run for a second that's it. So without even troubleshooting if that was the problem I replaced pump and it still won't fire. Has spark, and there's no fuel pressure at the rails. Put a test light at the fuel pump fuse and fuel relay was good. I also put a test light at the green/ black wire at pump with key on and showed no power also tested same wire but right after it comes out from under the fuse panel under hood and it also showed no power going to it. And now from here I'm lost I don't know where to look next. I thought I read if crank sensor is bad it will tell computer not to send fuel but I thought I'd come here and ask before I start throwing parts on it. Thanks

 

The PCM will only run the fuel pump for about 3 seconds when you first turn the key. After that, it needs to see the engine turning to trip the relay again. Does the pump prime at all when you first turn the key on?

 

No we could not here it prime

 

Just because you have power at the relay doesn't mean it's good. It needs to engage to allow power to go to the fuel pump.

 

We also tried switching all the relays around and still wouldn't fire

 

Does the relay click when you first turn the key? (probably have to have a finger on it to tell for sure....)

 

 

Fuel pump gets its power via the relay in the PDC, if the relay doesn't send it power, the fuel pump doesn't run, therefore, the engine doesn't run. If you don't hear the pump priming, you have either a pump problem, or a power problem. Verify if you get power back to the pump. (again, only for three seconds when you first turn the key on.) Take it from there.

 

We're not getting power at the pump. I put a test light on the green blk wire and had someone turn key no power. Switched relays around and still nothing

 

Does the ASD send power to the coil, or injectors for a few seconds when you turn the key on?