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really having a hard time figuring out why my fuel pump is not turning on....it's good, relays good....took it out and bench tested it twice....something in the wiring.....can't I simply power it myself?..toggle switch on the dash....does it really matter if the relay or oil pump powers it???? Might be a stupid question, just tired of looking and not driving....
really having a hard time figuring out why my fuel pump is not turning on....it's good, relays good....took it out and bench tested it twice....something in the wiring.....can't I simply power it myself?..toggle switch on the dash....does it really matter if the relay or oil pump powers it???? Might be a stupid question, just tired of looking and not driving....
i'm back again -- when you say, the fuel pump is good, have you powered it with 12V at the gas tank, NOT a bench test? from previous posts and threads, you have an opened circuit somewhere --
run a continuity check from pin A of the relay connector to either side of the FP fuse. run the same check from pin B of the oil pressure switch to the FP fuse. now unplug the fuel pump, and run the same continuity checks from the connector that plugs into the FP. if you do not have continuity with the above checks, you have an issue with the fuse panel, specifically the FP wiring. if the above checks for continuity, the issue is at the pump. there is a 15-pin connector behind the instrument panel -C209 - pay attention to the tan/white wire (fuse panel side) and the mating connector - light blue wire, and connector C237, red wire/red wire - again below the fuse block. if you can, apply 12V at these locations. virtual troubleshooting, even with something this simple can be problematic. just a wild *** guess, but my gut feeling is you may have a connector problem or a grounding issue with the fuel tank itself.
don't be a bubba - fix the existing wiring problem, and NOT power the fuel pump directly - just my 2 cents. keep at it, you'll figure it out. again, good luck my friend....
As long as it's fused you can. Down side you have to manually turn pump off in an accident.
the oil switch is near distributor. I'm not a fan of backyard repairs, but it would make car operational. I would still try to fix it correctly.
really having a hard time figuring out why my fuel pump is not turning on....it's good, relays good....took it out and bench tested it twice....something in the wiring.....can't I simply power it myself?..toggle switch on the dash....does it really matter if the relay or oil pump powers it???? Might be a stupid question, just tired of looking and not driving....
Can you sleep with your sister? As Obama would say "Yes we can". Should you? That is another question. Can I run a wire to the pump? Sure. Should I? Probably not. The oil pump doesn't power it. That is the backup in case something goes wrong with the primary circuit.
i'm back again -- when you say, the fuel pump is good, have you powered it with 12V at the gas tank, NOT a bench test? from previous posts and threads, you have an opened circuit somewhere --
run a continuity check from pin A of the relay connector to either side of the FP fuse. run the same check from pin B of the oil pressure switch to the FP fuse. now unplug the fuel pump, and run the same continuity checks from the connector that plugs into the FP. if you do not have continuity with the above checks, you have an issue with the fuse panel, specifically the FP wiring. if the above checks for continuity, the issue is at the pump. there is a 15-pin connector behind the instrument panel -C209 - pay attention to the tan/white wire (fuse panel side) and the mating connector - light blue wire, and connector C237, red wire/red wire - again below the fuse block. if you can, apply 12V at these locations. virtual troubleshooting, even with something this simple can be problematic. just a wild *** guess, but my gut feeling is you may have a connector problem or a grounding issue with the fuel tank itself.
don't be a bubba - fix the existing wiring problem, and NOT power the fuel pump directly - just my 2 cents. keep at it, you'll figure it out. again, good luck my friend....
If I power pin A, I get 12v at the fuse....still doesn't turn the pump on..if I plug the relay back in, key on....no voltage at the fuse.... very strange....12v at G at the aldl does nothing....there's a three wire connector going to the pump...purple goes to the sender...grey i'm sure is power and black ground....I guess i'll ground black and p0wer grey and see if it comes on....
If I power pin A, I get 12v at the fuse....still doesn't turn the pump on..if I plug the relay back in, key on....no voltage at the fuse.... very strange....12v at G at the aldl does nothing....there's a three wire connector going to the pump...purple goes to the sender...grey i'm sure is power and black ground....I guess i'll ground black and p0wer grey and see if it comes on....
go to your FSM - in the back, there should be several, multi-folded, multi-page copies of actual schematics. find this -
this is the 3-pin connector for the fuel pump. the black wire on the plug in connector is indeed (chassis) ground (circuit ground 150) - run a continuity check to a good ground point. the other two wires go to connector C209 (under the dash, near the fuse panel). pins "L" and "E" respectively, circuit wires 120 and 30 -
run a continuity check on those two wires from the fuel pump connector. circuit wire "120" eventually go back to the FP fuse. run a continuity check. circuit "120" now becomes circuit wire "458" and ties in to the oil pressure switch, the fuel pump relay and the ECM. check wiring continuity...
the third wire of the fuel pump connector is circuit "30" (pink wire) and eventually goes back to the instrument panel LCD display - most likely the fuel gauge - ignore it at this point. do not apply 12V or run a continuity check. . you'll be getting into microcircuits, and might as well leave well enough alone.
use the actual multi-page circuit schematic and systematically check the fuel pump wiring. you only have power and ground to deal with - there has to be an open or ground issue. hang in there....
I certainly appreciate all the help.....this stuff is not my forte, i'm better with wrenches.....It's not like it's my daily driver, I can wait until I find the problem...it's got to be something really stupid, which is right up my alley...
I certainly appreciate all the help.....this stuff is not my forte, i'm better with wrenches.....It's not like it's my daily driver, I can wait until I find the problem...it's got to be something really stupid, which is right up my alley...
one thing - not sure I ever got an answer to this -- unplug the fuel pump - check the car's wiring harness ground wire, the black wire - do you indeed have a good ground? from everything I've been reading, it sure sounds like there is a fuel pump ground issue. if you don't have a good FP ground, you can apply 12V to that thing til your blue in the face, and the FP will not turn on. I was thinking the fuel pump may also be grounded via the fuel tank itself, but that may not be the case. the fuel tank has "static" ground straps to the car's frame, but that may not provide a ground the pump.
OP - in another thread you mentioned I believe that the car ran for 15 minutes. Nearly every mid 80's fuel pump I recall replacing (NOT C4) I believe that I needed to use a different connector to the pump that required splicing internally. In that thread I mentioned the bulk-head connector.
I don't quite follow some of what you've posted since that thread but I'd back up and start fresh. You mention the new pump runs on bench, somewhere you mentioned 6V.
You never mentioned how you confirmed the "bench run" - pump still attached to the tree or removed from the tree.
I believe you've mentioned 'electrical ain't your forte' so I hadn't posted to this thread. I might know how I'd check but I don't know that I'd try to lead you through it.
Do you know that you're checking the correct relay etc.
OP - in another thread you mentioned I believe that the car ran for 15 minutes. Nearly every mid 80's fuel pump I recall replacing (NOT C4) I believe that I needed to use a different connector to the pump that required splicing internally. In that thread I mentioned the bulk-head connector.
I don't quite follow some of what you've posted since that thread but I'd back up and start fresh. You mention the new pump runs on bench, somewhere you mentioned 6V.
You never mentioned how you confirmed the "bench run" - pump still attached to the tree or removed from the tree.
I believe you've mentioned 'electrical ain't your forte' so I hadn't posted to this thread. I might know how I'd check but I don't know that I'd try to lead you through it.
Do you know that you're checking the correct relay etc.
It ran (you say) once!!!
right after I put the new pump in, it ran great for a few minutes for a couple of days, I thought everything was alright but when I finished putting in a tranny cable and started it, it died while I was testing nuetral/park/reverse, etc...haven't gotten it started since. I testing the right relay, on the firewall driver's side on the 85, had to put a new on in a few years ago....checked and cleaned all the contacts on the various plugs....I bench tested the starter with a 6v battery off the tree....even the old pump worked in that test.....i'm leaning now towards the fuse at the fuse box...it may be loose or not making contact...it's not in a good place to see....guess i'll have to open it up to check it all out...tomorrow i'm going to supply both a ground and 12v down the black/grey wires from the plug in the back going down into the tank....there's a purple wire there also, but I know it goes to the sender....have pulled and check all those connections twice, but haven't tried to send power down. still don't think that's it since I can get 12v at the fp fuse, if I send in down pin A of the relay but nothing if I plug the relay back in....if it doesn't work, it'll be off to check the continuity of those wire segments Joe C sent. I certainly appreciate the help, I had a lot when I first put it together a few years ago....guys on here have helped me keep it going.... got two cherry bombs coming out of the x pipe and then out the back....when it does start...
Ok. I had a similar issue a few years ago with my 90 and the ECM fuse was blown which caused me not to get power to the fuel pump.
My car is not available at the moment so I can't verify but we are talking about the ECM fuse that is supplying power to the ECM. Where is it exactly? Also what else happened? Did the gauge give any information or did it even crank?
11-30-2017, 05:29 PM
hot wired fuel pump????
