fuel pump wont run through relay but will when junped out. what is the circutry that is assoicated with the fuel relay?
2004 Dodge Ram 1500 W/ 5.7 L hemi.
Make sure battery has a full charge and connections all good. How long since a tune-up? Any applicable trouble codes? If it cranks good but won't start, have a helper crank it while you visually check for spark at the plugs? Also, check fuel injector pulse? If you have both of those then I think the cam and crank sensor signals are ok. If your missing those, I'd have to cam and crank sensor signals. I don't know how you tested the fuel pump? The fuel pump relay has two sides, the switch side and the control side. If you unplug the fuel pump relay and use jumper wire on the switch side of relay, terminals 30 and 87, the pump should run. If so, may be a problem on control side of relay, the control side needs voltage and ground. In diagram, the ptc fuse is voltage for control side of relay, that lower brown wire is ground and controlled by the pcm.
I think I found the answer. I changed the ignition switch a while ago. after running out of places to look I looked at the switch again. This is after I reinstalled the old switch once i cleaned the contacts and adjusted the spring tension on the contacts. I found that a few of the connections for the wires were loose. I tightened them and reconnected the switch. But this still didn't cure the problem. I looked closer at the plug and found that the connectors had pushed out the back of it.I pushed them back in a reconnected the Neg. Battery terminal and tested it. That was the trick, everything works well now. I advise anyone having similar problems to check the Ignition Switch connector wires. This is also where up need to look for a problem with the circulating cab fan. These terminals burn due to high current flow, but now i may think it might just be because of a loose termination.