nasty electrical problem

[jarhead720]

Alright guys I've got an 89 xj 4.0..the fuel pump wont work unless it is wired to battery or another hot wire..at the fp relay it has power on one terminal when ignition is on but doesn't have a 12v constant..it is the same for the pump it has power at the pump but when cranking power drops to zero..the fuel pump will not kick on at all unless jumped...I tried jumping relay terminals 87 and 30 if I ain't mistaken and it still won't kick on..I no that it has a fusibe link by the starter relay.just don't know which wire..also the wires coming from the starter relay are about melted..in conclusion can anyone point me in the right direction here..I have to drive 40 miles one way to physical training twice a week and really need this fixed asap..also before I had the fuel pump jumped from the relay and wired into the ignition worked great until the day before yesterday the fuel pump went out..the guy I had put the new one in said that you can't wire it to the ignition because it will burn them up is there any truth to this?...thanks guys

 

[superj]

If it worked previously, I would go back to that set up

 

[jarhead720]

If it worked previously, I would go back to that set up

Could it cause a pump to fail having it wired to the ignition?

 

[greg92jeepxj]

Long time since I had my hands on an'89 (AMC) , so I'm reading from a '92 FSM (chrysler). First , look for a ballast resistor on the firewall near the master cylinder . See if you are getting any reading through it. This carries voltage to the pump relay at fuse #6. Check fuse #6 in the PDC . This also powers the auto shutdown relay. BTW , it's NOT safe to hard wire the fuel pump WITHOUT a fuse . This practice has produced fires. Not clear from your post if you are in fact receiving voltage from terminal 30 but you posted receiving 12 V constant but no go when terminal 30 & 87 jumped out. Verify ASD (auto shutdown relay) terminal 87 live with key on and cranking. Again , I'm reading fro a chrysler '92 diagram but I hope this may help as I'm not certain whether the wiring was similar.
P.S.- my diagram dosen't show fusible links for the '92 model year , just a starter and pump relay (PDC). Also . Check for a ballast resister relay which may be found clipped on the power distribution center (PDC) or close by. Your losing electrical signal somewhere .

 

[superj]

89 is still a renix engine so not sure the 92 fsm will fit since 92 was chrysler injection. still try though.


and as long as you are fused, the fuel pump cannot fail from being wired to the ignition. not having a fuse, it won;t fail either but it could for sure start a fire unfused

 

[jarhead720]

Long time since I had my hands on an'89 (AMC) , so I'm reading from a '92 FSM (chrysler). First , look for a ballast resistor on the firewall near the master cylinder . See if you are getting any reading through it. This carries voltage to the pump relay at fuse #6. Check fuse #6 in the PDC . This also powers the auto shutdown relay. BTW , it's NOT safe to hard wire the fuel pump WITHOUT a fuse . This practice has produced fires. Not clear from your post if you are in fact receiving voltage from terminal 30 but you posted receiving 12 V constant but no go when terminal 30 & 87 jumped out. Verify ASD (auto shutdown relay) terminal 87 live with key on and cranking. Again , I'm reading fro a chrysler '92 diagram but I hope this may help as I'm not certain whether the wiring was similar.
P.S.- my diagram dosen't show fusible links for the '92 model year , just a starter and pump relay (PDC). Also . Check for a ballast resister relay which may be found clipped on the power distribution center (PDC) or close by. Your losing electrical signal somewhere .

I replaced all the wiring from starter relay to the fp relay..and from relay block to main wiring harness..and she fired right up thanks guys I appreciate the help.

 

[greg92jeepxj]

Glad you got it worked out , sorry it was a detailed repair . Good job and good luck at PT ! Happy holidays brother ! Greg

 

[superj]

you at lejuene?

everything is a long drive there?