Does anyone know what color the wire is on the fuel pump and which plug it is in that I need to connect my fuel guage to on a '98? The Chilton book for my truck is useless!
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Does anyone know what color the wire is on the fuel pump and which plug it is in that I need to connect my fuel guage to on a '98? The Chilton book for my truck is useless!
my pump wire is brown and the ground is black. Alldatadiy.com? Maybe Hummertech or NITROUS has a harness diagram for you.
I already fried my Auto meter fuel guage because I went by the chilton book. I went and bought an Equus guage to replace it and I don't want to fry it too. The Chilton manual says its a pink wire that goes to the guage but there is no pink wire coming from my fuel pump. :whack:
Grey wire is power to the pump. Black/white stripe is ground.
Ok, so what are all of the other wires for? Does yours show a purple/white wire?
Purple is Fuel Gauge Sensor Signal (from VCM to intsr. cluster)
Ok here is what Chilton is telling me. One schematic that reads 1988-98 c/k wiring says:fuel pump/fuel guage -pink-to fuel guage. Then another schematic reads 1988-98 c/k wiring says:To fuel guage(tank unit)-ppl-W connecter of the instr. panel connector. I don't see a pink wire on either one of the plugs on my pump and I only see a purple/white stripe wire, no solid ppl.
<div class='quotetop'>QUOTE(NITROUS @ Jun 29 2006, 05:07 PM) [snapback]56706[/snapback]</div>Thanks Nitrous. Stupid question for ya, where is the VCM?Quote:
Purple is Fuel Gauge Sensor Signal (from VCM to intsr. cluster)
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I'm at work and I can't remember if it had a white stripe or not. I'm fixing to leave so I can get you all the information you need from the dealer manual as soon as I get home.
That's the old computer you took out.
FWIW, generally pink wires are switched power leads and red wires are constant 12V sources. Black and black/wt are almost always grounds. Process of elimination may help. Grey is fuel pump power so there goes that one.
I'll check back on this thread when I get home, later bro's
I actually never took it out, so do I need to connect to the wire coming from my old computer or the fuel pump itself?
OK here is what I've got: gray, black, ppl/white on one plug and blk, grn, gray on the other plug. So I'm guessing it's gonna be the ppl/white wire but I'm gonna wait on Nitrous to confirm it before I fry another guage. Thank for yalls help guys! :hshake:
Damn, that's a bitch that you fried a brand new gauge. Do you have a multimeter? You should be able to check the voltage on the wire to verify it's under 12v. Rocking the fuel tank, if the tank's not full, should make the voltage fluctuate.
Yes but it's a POS from Wally world and it only works intermittantly, so I can't trust it.
Here you go, Do you remember your old oil pressure switch? It's tied to the fuel pump and sender also. Actually it's an oil pressure switch and gas sensor. It used to be located by the your old distributor and is key to your wiring.
Orange - Hot at all times (87 on relay) Goes to Oil pressure switch / sender and old VCM
Grey - oil pressure switch and sender 5 volt reference to VCM and or fuel pump power
Black - Ground
Purple/white - Fuel level signal to old VCM
Purple - To instrument cluster
Black/white - Fuel pump relay (86 on relay)
Red - Fuel pump prime connector (87A on relay)
Dark Green/white - (85 on relay) to old VCM
Black - Ground to VCM
Pink - Goes to old injectors on Vortec motor
Dark green - Fuel tank pressure to old VCM
Hope this helps out. BTW, the 4.3 and 5.7 wiring diagrams are pretty much the same. I wasn't sure what you had before.
So basically I can just use the ppl/wht wire from the pump(I've got the bed off right now) or do I need to use the ppl wire coming off of the vcm?
Yes, that should work.
Do you still have your original fuel gauge? If so, why not use it?
OK thanks alot guys I really appreciate it. Now hopefully my guage will work and be accurate. I'm tired of driving around without a gas guage. Thanks again :hshake:
Did you see my reply?
No I am using all Autometer guages. I couldn't figure out how to make my factory stuff work. I tried but that Chilton book just wasn't cuttin it. I didn't realize you had all the schematics until after I had already installed all the Autometer stuff. Oh well, it looks sweet as hell imo.
If you want to get the factory stuff working again, let me know. It's easy.
Will do, I still have it all. I'll let you know. Hey BTW can I axe my old vcm?
I did, It was just in the way. There's no need for it like everyone say's. Do you have it hooked to anything? If so let me know first.
Well it doesn't work! :help: I don't know what to do. I hooked it up to the ppl/wht wire at the pump, grounded the guage, switched 12V to the guage and it does absolutely nothing.
I wonder if the sending unit is actually grounded? I am assuming it is, but if it goes up to the engine bay to ground somewhere there is a possibility that I cut it. I guess I'll check that tomorrow. Also I don't have a clue how to identify the solid ppl wire that Nitrous is talking about. There are 4 plugs on the vcm and each has some purple wires. ?????
The fuel sending unit must be a 90 ohm unit. It obviously is designed for use in a tank that the fuel sending unit has one side grounded and the other side going to the gauge. I looked at the instructions online and they're really simple looking. Now if only someone had a wiring schematic for you for the fuel tank sending unit. You could always drop the tank and check it out for yourself but that's just too much work. Got a salvage yard handy somewhere close to you? Maybe you can find a vehicle there and compare what's going on in one of their tanks to keep you from dropping the tank or removing the bed so you can figure out the wiring in yours. If I had not sold my 98 LS1 fuel module I would be able to see what was going on in there.
I've got the bed off right now. What do I need to check?
See what color wires go to the resistor in the in-tank fuel sender. There should be two wires going to the sender. You need to find which ones go there so you can wire one side to ground and the other to the gauge. It will also help you to measure the resistance of the sender while you have it out. Measure the resistance with the float all the way up and then all the way down. According to the IQUUS manual it should be 90 ohms.
Well my bro-in-law has my ohm meter and my truck was tore apart at my buddies house and I'm tired of F-ing with it. I checked to see that it was all grounded and decided to just put the bed back on & call it quits. When I go back to work tomorrow I'll get a new pump and check it out. This guage is for empty=0 ohms and Full=90 ohms GM vehicles, that's what all late model GM senders are I thought. I'll check one out tomorrow. Thanks again for yalls help.
Hey Red how did your head swap go? How much of a difference did they make?
Head swap was a piece of cake. Now I've got to get a retune. It runs great but pings on hot days on 87 octane and full throttle runs. Maybe too much timing for cheap gas. You can sure hear the cam now. It rocked before but it seems to rock harder now.
I always run 93 octane even though I could probably get away with less since my heads are only 69cc. It seems like I can hear my cam alot more here lately too. I don't know if it's because I ported my TB or it's just getting a miss :laugh: . So are you gonna wait to get a retune before you take it to the strip? Hey BTW mark it down on your calender Aug. 24 is Summers Last Blast in Vernon Tx. and after the cruise is over at 10:00, WRP has heads up drag racing. It's usually pretty badass. A lot of bad to the bone cars come out of the woodwork. I think it would be cool to get alot of us LS1Truck guys to show up and crash the party. :rock:
All the badass Okie cars come down to show how it's done, huh. That might be possible, that's my B'day weekend. Nice way to celebrate for me. The fam will just have to stay home. :taunt:
Actually I think alot of cars from the DFW area come up. There are are some local boys with a King of The Hill car and guys always come from Kennedale to run for $. Last year there was an old Pinto station wagon(ugly as fuck) from DFW with an LS1 and some spray, street legal, he drove it to WRP from Dallas. Anyway he was damn near dragging the bumper for 60 ft. Just alot of fast as hell street legal cars show up.
motoxlifer, how much of your original harness do you still have? I think you should go back original but that's your choice. Did you use the LS1 or 98 oil pressure switch? And did you install the oil pressure switch by the oil filter in the block off plate?
I have all of the harness. It's just in 2 pieces. :laugh: I have the vcm with all 4 plugs and probably 1 1/2 ft of the wiring still in the truck. I am using a mech. oil pres. guage tapped into the hooter above the oil filter.
No problem. Let me know if you want to go back stock and I can give you allthe wires you need to keep from the old VCM. BTW, did you have a 4.3 in there?
Yes it was a 4.3