rja

my 94 grand cherokee limited 5.2 is slow to send power to the fuel pump when starting. sometimes it starts immediately and more frequently now it takes several attempts to get the fuel pump to click. have replaced fuel pump relay.
when I jump 30 to 87 the pump starts instantly, but when you turn the key sometimes the fuel relay and the shut down relays "dance" for a few seconds before the pump comes on, then it starts instantly. never dies or shows any hesitation after it starts, runs fine plenty of power. battery is getting older but shows just over 12 volts. the ground connections seem tight. also the fuel gauge stopped working before the starting problem appeared. HELP

dave1123

Welcome to CF!

I sounds to me like bad connections in the plug at the fuel tank. The gauge sending unit really doesn't have any current and is just the third leg of a resistance bridge so good clean connections are critical to it's function. If the plug connections are dirty or corroded, the fuel pump and the gauge won't work properly. On the start-up cycle, the fuel pump just runs briefly to pressurize the fuel rail. After the PCM detects a signal from the CPS that the crankshaft is actually turning, it energizes the fuel pump, injector circuit, and the ignition. of course, if the fuel pump isn't running, it won't start.

Just for grins, get your battery load tested. Sometimes with a marginal battery, the starter pulls enough amperage so there isn't enough energy for the rest of the systems.

rja

Thanks for the reply. I had cleaned the tank connection and tested the circuit by jumping the 30 to 87 contacts, the pump starts instantly. The rapid clicking of the fuel pump and shut down relays for 3-4 seconds before the fuel pump relay seems to finally make good contact makes me wonder about the computer.
I will load test the battery but when it doesn't start on first try I don't even try to start the engine again until I hear the pump. Thanks

Bustedback

Have the battery load tested.