so i put in a brand new bosch fuel pump because the one in there was crapping out. it was really hard to start the jeep because the fuel pump wouldnt turn on until i cranked and cranked and cranked. so i replaced it and now my jeep wont start at all. the fuel pump will just not turn on. im wondering if there is some type of safety thing where if i messed up some wiring would it just not turn on? could there be anything else to check that i may not have done right? im just in a bind here i need the jeep up and running, not to mention im going wheeling in the next couple weeks so i need this figured out. thanks in advance for any replies...

 

bump..

 

bump.. noones got anything?

 

Well if your certain it started acting this way just after you replaced the pump it probably the pump bleeding off pressure. You could do a pressure leak down test. Put a fuel pressure gauge on your Jeep, start it and see what the pressure is (should be around 36psi ~ish), then turn it off and watch to see if the pressure starts to decrease. Anything more than a few psi drop is no good! This is a sign of a bad pump which happens more often than you think. Try returning the pump under warranty. I work at a parts store and have my own shop and just encountered this exact problem on a '93 Chevy truck.

 

my jeep does the same thing but i know thats its vac lines.have you checked all filters?..maybe grounding on the pump?

 

Go back to basics.....verify that you have a good ground at the fuel pump wiring harness and verify that you have fuel pump command on the dark green wire with red strip for 5-8 seconds when key turn to start position.

 

As Willys55 points out, when you turn the ignition to on, the fuel pump will run for a few seconds. You should be able to hear it at the fuel tank. If no sound, check for power at the fuel pump electrical connector battery side. If the circuit is good, you should have power. You can check the pump for operation by running a jumper cable from the battery to the fuel pump connector. The pump should run if it is good.

If the pump circuit is bad, check the fuel pump fuse, the fuel pump relay and the ASD relay. The PCM and ASD tell the pump to run.

If you need info on testing a relay, see this thread, post #7