hey all, what all would cause the fuel pump to kick on and off in my 96 cherokee?

when i put the key forward but dont start it the pump kicks on, then shuts off, then kicks on and off at different times with the key forward, the jeep has a really hard time starting, if i hold my foot to the floor it will sputter and try to stall.

i have a video of what its doing also if that will help. i tried to replace the relay, (nothing) and this is its second computer and its doing the same **** it was doing before.

thanks for all the advice!

 

no one has any idea?

 

By design, the fuel pump should energize and run for approximately 2 seconds when the key is turned to the on position.

Then it should turn OFF.

The fuel pump will come back on again when upon cranking the engine over, the computer receives the proper input signals and knows that fuel is needed, so it sends out the control signals that energize the pump and keep it running while the engine is running.

 

You might have a bad pump or fuel pressure regulator. You should hook a gauge up and see what your fuel pressure is doing when you turn the key on. If your fuel pressure is dropping after the pump kicks on that might be why it is kicking on again.

 

thanks, ill give that a shot, i have a fuel pump for it so maybe thats the problem.

 

i was also thinking either fuel pump or ignition switch, because when the pump kicks back on the gen and check engine light lights up

 

The pump should only kick on for 2-3 seconds and only once when you turn the key on. It wont run again until the computer sees the engine cranking. If your crank sensor was bad it might be giving a false reading causing the pump to kick on and off and also cause your hard start. Try unplugging your crank sensor and see if the pump cycles on and off the same.

 

i'll give that a shot too, that is a brand new CPS though

 

Does your tachometer bounce? I am having a similar problem with my 1993 Subaru. My tach bounces koeo. I'm thinking I might have a bad sensor ground on the ecu. The fuel pump is cycling on and off and I think the computer thinks its cranking