ckjeep Posted April 2, 2014 Share Posted April 2, 2014 ok i have asked a few different questions as i work on this truck. my latest question involves the fuel pump wiring done by the previous owner.the wire that hooks to the starter relay to energize the fuel pump is pulled off and wired to the accessory on the fuse block. this works fine except the pump is running anytime the key is on. i hooked the wire back to the starter relay but the pump only works if the key is actually in start position. as soon as you let go of the key the pump stops. i can drive it like it is but i was just wondering if anyone had any ideas? thanks Link to comment Share on other sites More sharing options...
dave92cherokee Posted April 2, 2014 Share Posted April 2, 2014 There should be no wire going from the starter relay to the fuel pump relay or fuel pump. The battery goes to the starter relay and fuel pump relay and most everything else through seperate fusible links. You didn't tell us what engine it's got but if it's the 4.0 there should be the red wire with the fusible link in it, orange wire which provides the power coming out of the relay, orange/tan wire which provides the ground for the relay, and yellow wire which connects to the ignition control module and ECM ignition signal to energize the relay. This would make it so that as soon as the truck is put in the on position it energizes the relay and turns on the fuel pump to prime it like it's supposed to. Looking at the ignition switch there should be a yellow wire that has power when it's in the on and start position but not when in the accessory position. Link to comment Share on other sites More sharing options...
ckjeep Posted April 2, 2014 Author Share Posted April 2, 2014 sorry it is a 4.0.the orange wire marked f on the relay is the one pulled off and wired to the fuse box Link to comment Share on other sites More sharing options...
Eagle Posted April 2, 2014 Share Posted April 2, 2014 The '88 and newer XJs and MJs have a ballast resistor in the fuel pump circuit. It should be a whte ceramic block about 3 inches long on the innder fender of the driver's side, near the air filter box. The ballast resistor reduces voltage to the fuel pump when running to reduce noise. The starter circuit has a by-pass so the fuel pump gets full voltage when starting. If you get power with the key in START but not in RUN, the ballast resistor may be blown. It can be easily replaced, but it can also be by-passed, either for testing or permanently. (The 87s didn't have it.) Link to comment Share on other sites More sharing options...
ckjeep Posted April 3, 2014 Author Share Posted April 3, 2014 it has what appears to be a new ballast resistor but i will try to bypass it tomorrow. eagle.. that is what it does. it will actually run as long as you keep the key in start but as soon as you let off it dies. if the ballast is good are there any other possibilities? thanks Link to comment Share on other sites More sharing options...
ckjeep Posted April 4, 2014 Author Share Posted April 4, 2014 ballast is good.fuel pump doesnt energize at all unless the orange/black stripe wire from the starter relay is wired to the fuse block.any ideas anybody? Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now