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08-22-2022, 04:25 PM | #1 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
Posts: 5,175
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No power to the fuel pump
I wired my fuseblock up similar to lt1swap. I don't think I'm getting any power to the fuel pump. I don't hear it click on at all. the tan wire in my picture (which should be equivalent to the orange wire on lt1swap diagram) has power to it, but my purple wire does not (which runs to the fuel pump). I pulled the fuse and ran a jumper and didn't notice any difference.
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-22-2022 at 05:30 PM. |
08-22-2022, 04:46 PM | #2 |
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Re: No power to the fuel pump
First thing I would to check is if you have 12 volts coming from the relay to the fuel pump with the key in start or run.
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08-22-2022, 05:10 PM | #3 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
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Re: No power to the fuel pump
with key off the tan wire has 12 volts. nothing else on the relay has power. with the key on, the tan wire is still at 12 volts, the green wire to the pcm oddly is reading . 01 volts... and the purple wire for the fuel pump feed still showing 0
the main relay seems right i think. key off on the big red one and the pink wire directly across it shows power. key on they both still show power, but the pink wire on top also has 12 volts
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-22-2022 at 05:26 PM. |
08-22-2022, 05:22 PM | #4 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
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Re: No power to the fuel pump
whats also odd...or im not sure if its supposed to be that way. but i probed all the regular fuses and they all show 12 volt too, no matter if the key is off or on
i added another diagram i followed to make my fusebox. i did seperate my wires more than they did just to pinpoint and troubleshoot more easily...so i do have an extra row of 12 volt keyed fuses. they are jumpered to the other row UPDATE i ran a wire directly from the battery to the purple wire and i heard it turn on
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-22-2022 at 05:59 PM. |
08-22-2022, 09:42 PM | #5 |
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Re: No power to the fuel pump
Pull the fuel pump relay and jump the tan and purple wires, that will tell you if the wiring all the way back to the pump is good.
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08-22-2022, 09:43 PM | #6 |
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Re: No power to the fuel pump
Doesn't sound like your ignition relay is wired right
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My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html |
08-23-2022, 10:54 AM | #7 |
low n' slo
Join Date: Mar 2009
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Re: No power to the fuel pump
ok I'll check with a jumper again when I get home. I followed that last diagram almost to a tee with the except of the fuel pump feed. I don't see what I could've done wrong.
for the 4 wires out of the LS harness..... the main relay battery power runs straight to the battery. the pink 12 volts key wire I wired it to the pink coil wire in the ez wire harness. and of course the fuel pump feed (purple wire on mine.. yellow on the other diagram) runs to the fuel pump.
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 01:57 PM | #8 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
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Re: No power to the fuel pump
ok, ran a jumper and the fuel pump does turn on, whether the key is on or off. probed all the connections and they are the same as mentioned above. as for the main relay, maybe that far left pink wire should be swapped with the bottom pink wire in the relay? im not too sure how its supposed to work, but the big red wire (top) has constant power, as does the pink wire opposite (bottom). the pink to the left only gets 12 volts with the key turned.
also, if i flip the relay over it goes likes this... big red power wire (top) - 87 black ground - 85 left pink wire - 86 bottom pink wire - 30 do the diagrams look correct?
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-23-2022 at 02:03 PM. |
08-23-2022, 03:21 PM | #9 |
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Re: No power to the fuel pump
87 should have constant 12v from battery
30 should go to the pump 86 should be switch on 12v 85 should be ground If you've got 12v on 87, you should be able to jump 30 to 87 and the pump will run.. Are you inline pump or intank?.. make sure the pump is grounded
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 03:29 PM | #10 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
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Re: No power to the fuel pump
ok 87 is a direct battery feed that is NOT bridged in the fuse block. it is split though, one to the fuse block, one to the MAIN relay, then it runs all the way to my battery junction.
i know its very hard to see and i do have another picture i will post shortly showing the underside wiring better. but 30 is bridged to connect ALL the pink wires in the fuse block. 86 - i soldered it to the "coil" wire in the ez wiring harness. which from my understand, is a keyed 12 volt source. if you look closely you can see i followed the diagram labeled "LS WIRING HARNESS" almost to a tee. the 30 on the relay that bridges to all the pinks, also bridges to the other row of fuses to also give them power. i really hope im making sense, wiring is NOT my forte
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-23-2022 at 04:34 PM. |
08-23-2022, 03:30 PM | #11 |
low n' slo
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Re: No power to the fuel pump
these are the pics kind of showing a little more of the underside...and my very horrible and un readable diagram lol
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 04:33 PM | #12 |
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Re: No power to the fuel pump
Ha..I hate wiring also.. best I can tell, it dont look right..when I get to work I'll get it on a big screen so I can see it better..
But your fuel relay should be like this
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 04:42 PM | #13 |
low n' slo
Join Date: Mar 2009
Location: rosenberg, texas
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Re: No power to the fuel pump
that's exactly how I have it.
the tan wire is 87 and runs to the orange wire 12 volts battery from the pcm (which is fused through the main big red power wire). 30 is the purple wire running all the way to the pump. 85 is grounded. my 86 is the green fuel pump wire from the pcm it's either I'm blind as a bat or dumb as a box of rocks lol. I keep looking over this fusebox and see no difference!
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-23-2022 at 05:17 PM. |
08-23-2022, 06:06 PM | #14 |
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Re: No power to the fuel pump
It sounds like you have more than one problem. Do all the fuses still have power with the key on or off? If thats the case, it isn't right.
So, you pulled the fuel pump relay and jumped the tan and purple wires and the pump turns on? If so, then the wiring to the pump is good. Pull the main ignition relay and see if the fuses still have power with the key on or off. They should not have any power. If they do, something is wired wrong. Its hard to tell in your pics. Pull that relay and report back.
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My '72 short bed build. http://www.ls1tech.com/forums/conver...6-0-4l80e.html 5.3 swap into my RUSTY '71 C10 http://ls1tech.com/forums/conversion...71-c-10-a.html |
08-23-2022, 06:17 PM | #15 |
low n' slo
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Re: No power to the fuel pump
pulled both relays and yup, all fuses still show 12 volts
and yes, with a jumped wire I can hear the pump kick on
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] Last edited by kev2809; 08-23-2022 at 06:23 PM. |
08-23-2022, 08:08 PM | #16 |
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Re: No power to the fuel pump
the 86 wire should come from the switch with 12v key on and crank..
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 08:10 PM | #17 |
low n' slo
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Re: No power to the fuel pump
are we talking the fuel pump relay or the ign relay?
if the fuel pump, then where does the green fuel wire from the pcm go?
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 08:13 PM | #18 |
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Re: No power to the fuel pump
on your drawing you have the fuel pump opposite of the ground
and 12v batt opposite of fuel pump pcm ..that dont look right i dont know what the green wire is supposed to do
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 08:16 PM | #19 |
low n' slo
Join Date: Mar 2009
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Re: No power to the fuel pump
right. the green wire is from the pcm pinned as fuel pump. the purple wire is opposite of the 12 volts battery wire, and that purple wire is the fuel pump feed wire. that's how the 2 diagrams above show it
is that not right?
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 08:22 PM | #20 |
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Re: No power to the fuel pump
hook a 12v jumper wire from battery to the green wire terminal and see if the pump runs
sounds like your not getting a 12v signal to the green wire with switch on and cranking i think im getting confused looking at the drawing
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 08:24 PM | #21 |
low n' slo
Join Date: Mar 2009
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Re: No power to the fuel pump
with the relays in?
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 08:25 PM | #22 |
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Re: No power to the fuel pump
yes.. or check the green wire with a meter and see if its getting 12v while cranking
probably like Eric said,, you may have issues elsewhere
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 08:35 PM | #23 |
low n' slo
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Re: No power to the fuel pump
with relays in, 12 volts straight to green fuel pump pcm wire, it does kick on
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67 1/2 ton Suburban - Project DRGNWGN. Build thread -_--_--_ _________ _--_-_ -/____|__|__\__ ,.,,,.,.,,.,|_O _______ O_] |
08-23-2022, 08:50 PM | #24 |
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Re: No power to the fuel pump
ok , so your not getting 12v to fire the relay
i keep forgetting , is this a store bought LS harness or garage built?
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Mongo...aka Greg RIP Dad RIP Jesse 1981 C30 LQ9 NV4500..http://67-72chevytrucks.com/vboard/s...d.php?t=753598 Mongos AD- LS3 TR6060...http://67-72chevytrucks.com/vboard/s...34#post8522334 Columbus..the 1957 IH 4x4...http://67-72chevytrucks.com/vboard/s...63#post8082563 2023 Chevy Z71..daily driver |
08-23-2022, 08:59 PM | #25 |
low n' slo
Join Date: Mar 2009
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Re: No power to the fuel pump
I built it myself. my main concern was the pump not kicking on when I turn the key forward.
and apparently I have another issue since all the fuses have power at all times.. even with the relay pulled out
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