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pretty sure there's an issue with ground on the fuel pump...not good with wiring but there's four wires going into the fp relay...can I not check them with something?...also 3 wires out of top of tank...is one of them ground which I can check?...finally, where does the wires all get grounded in the back of the car 85 c4 put in a new relay, and as I and everybody else with sense knew, didn't help.....can't force it on using 12 volts at "g" on the aldl, so now "guessing" it's something to do with ground....fuses check out. thanks for any help. fp is new and bench tested....Paul
Last edited by playsdixie; Nov 24, 2017 at 04:13 PM.
pretty sure there's an issue with ground on the fuel pump...not good with wiring but there's four wires going into the fp relay...can I not check them with something?...also 3 wires out of top of tank...is one of them ground which I can check?...finally, where does the wires all get grounded in the back of the car 85 c4 put in a new relay, and as I and everybody else with sense knew, didn't help.....can't force it on using 12 volts at "g" on the aldl, so now "guessing" it's something to do with ground....fuses check out. thanks for any help. fp is new and bench tested....Paul
should be 5 wires at the FP relay - this is off the top of my head, but on an 85, i'm thinking the actual FP relay ground is pin "B" - that relay, ultimately gets grounded at the thermostat housing - G103. since the relay contacts are to NC, it's odd that you can't turn the FP on with 12v at "G" of the ALCL diagnostic port. apply 12V at FP relay connector, pin "A" - that will eliminate the relay. double check the FP fuse (10amp). you can also short out the pins of the oil pressure switch connector - this should engage the fuel pump. the fuel pump itself, gets it's ground from the fuel tank via chassis ground. check the fuel tank itself for chassis ground. (maybe) try adding a secondary, temporary ground at the fuel tank. do you have a FSM? if not, get one!
edit: note - there seems to be some discrepancy whether it's G103 or G104 at the thermostat housing - I've seen it both ways in various FSM. my 85's FSM shows G103, the above 86 manual shows G104 - ???
edit2: the discrepancy might be due to the location of the 85 and 86's egr solenoids - the 86-91 FPR may indeed get it's ground at G104, which i'm thinking is the back of the LH cylinder head. G104 also grounds the ECM.
should be 5 wires at the FP relay - this is off the top of my head, but on an 85, i'm thinking the actual FP relay ground is pin "B" - that relay, ultimately gets grounded at the thermostat housing - G103. since the relay contacts are to NC, it's odd that you can't turn the FP on with 12v at "G" of the ALCL diagnostic port. apply 12V at FP relay connector, pin "A" - that will eliminate the relay. double check the FP fuse (10amp). you can also short out the pins of the oil pressure switch connector - this should engage the fuel pump. the fuel pump itself, gets it's ground from the fuel tank via chassis ground. check the fuel tank itself for chassis ground. (maybe) try adding a secondary, temporary ground at the fuel tank. do you have a FSM? if not, get one!
edit: note - there seems to be some discrepancy whether it's G103 or G104 at the thermostat housing - I've seen it both ways in various FSM. my 85's FSM shows G103, the above 86 manual shows G104 - ???
edit2: the discrepancy might be due to the location of the 85 and 86's egr solenoids - the 86-91 FPR may indeed get it's ground at G104, which i'm thinking is the back of the LH cylinder head. G104 also grounds the ECM.
Thanks for the info, I do have a fsm....I put 12v to "a" on the relay plug....no luck.....then tried my continuity tester on the FP fuse....I get power on the left hand clips of the fuses but one...the FP fuse....it's not getting power....any ideas?????
Thanks for the info, I do have a fsm....I put 12v to "a" on the relay plug....no luck.....then tried my continuity tester on the FP fuse....I get power on the left hand clips of the fuses but one...the FP fuse....it's not getting power....any ideas?????
not sure I fully understand what you're saying. you're not getting 12V on the 12V side of the FP fuse holder - ??? - if that's the case, I would think there is the problem. did this issue just pop up out of nowhere? maybe, just for the hell of it, replace the fuse with another. also, check for continuity between the fuse holder and the fuel pump connector. the circuit seem to be open somewhere - you just need to find out where it is. can you probe 12V at the fuse panel and get the fuel pump to turn on -- how about 12V at the fuel pump connector itself? good luck.
not sure I fully understand what you're saying. you're not getting 12V on the 12V side of the FP fuse holder - ??? - if that's the case, I would think there is the problem. did this issue just pop up out of nowhere? maybe, just for the hell of it, replace the fuse with another. also, check for continuity between the fuse holder and the fuel pump connector. the circuit seem to be open somewhere - you just need to find out where it is. can you probe 12V at the fuse panel and get the fuel pump to turn on -- how about 12V at the fuel pump connector itself? good luck.
I thought the old fuel pump was intermittent, the car had died but restarted a couple of times this summer....when I put a new pump in, it started right away but died in the driveway....I have replaced the fuse...all the other fuses test for 12v but the fp fuse. I tried to put 12v at the fuse pump clips but no luck.
I thought the old fuel pump was intermittent, the car had died but restarted a couple of times this summer....when I put a new pump in, it started right away but died in the driveway....I have replaced the fuse...all the other fuses test for 12v but the fp fuse. I tried to put 12v at the fuse pump clips but no luck.
not sure I can add any more here - can you get the pump to turn on with 12v directly at the pump connector? if you can, work back to the fuse block. there's either an internal issue with the fuse block itself, or you have an open circuit somewhere between the fuse block and the pump itself. hang in there, you'll figure it out. good luck -
one thing here - you will not see 12V at the FP fuse UNLESS the relay energize or you have sufficient oil pressure to close the pressure switch. not sure what you're doing - are you probing with a 12V supply, and have you applied a 12V supply directly to pin "A" of the FP relay connector, or are you just probing with a multi-meter???
edit: sorry - I see in your original post that you applied 12V to pin "g" of the ALDL connector -
fuel pump ground
