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91camaro_rs Member
Joined: 03 Dec 2008 Posts: 1712 Location: Fox Island, Wa
1991 Chevrolet Camaro RS
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Posted: Sat May 10, 2014 11:27 am Post subject: tbi to carb help |
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Okay so im helping convert a 91 tbi 350 to carb. I seperated all the ecm wires from guage wires but there are 3 things I cant figure out.
1. Oil pressure wiring. Orange brown and gray I believe only the gray one goes to guage. What do I do with the other two?
2. Fuel pump and relay. Using stock pump with aftermarket regulator. Theres 5 or so wires coming out of that relay/plug how should I run the rest of the wires that would have went to ecm? Or should I just wire the pump to ignition 12v so pump comes on that way...
3. Torque converter lockup plug...I have no idea what to do with
Thanks in advance! _________________
'91 Camaro RS 5.7 TPI- 700r4- 3.27 posi- headers- chambered exhaust- |
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Quasi-Traction "I have petals"
Joined: 24 Oct 2005 Posts: 3873 Location: stumptown
1986 Chevrolet Camaro Berlinetta
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Posted: Sat May 10, 2014 6:41 pm Post subject: Re: tbi to carb help |
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91camaro_rs wrote: |
1. Oil pressure wiring. Orange brown and gray I believe only the gray one goes to guage. What do I do with the other two?
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I'm not 100% sure on this (If someone can confirm?), but I think the other two are for an oil pressure switch. when the switch is out, the fuel pump doesn't prime, kind of a fail safe thing. If you're going carb, this probably won't effect you. |
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Al Hasse Member
Joined: 19 Nov 2005 Posts: 4379 Location: Bremerton, WA
1992 Chevrolet Camaro RS
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Posted: Sat May 10, 2014 7:54 pm Post subject: |
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When the fuel pump relay fails, the switch in the oil pressure sending unit will energize the fuel pump when oil pressure builds up. I went through three of those 3 wire units at Auto Zone because they were wired backward and turned on my fuel pump as soon as I plugged them in, finally went to NAPA and got one that works. _________________ 92 Camaro
89 Camaro
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Sat May 10, 2014 8:32 pm Post subject: |
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Do not run an electric fuel pump into a carb without an oil pressure kill.
The factory GM unit is a trigger, not a kill.
Proper way to do it is to get a oil pressure switch that closes at a low PSI and use it to ground out the pump relay.
You will need a vacuum lockup control for the 700.
It's problems like this that are god's way of telling you that what you're doing is dumb and wrong. |
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Xophertony Rodeo Queen
Joined: 13 Oct 2005 Posts: 5304 Location: Portland, Oregon.
1988 Pontiac GTA
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Posted: Sat May 10, 2014 9:45 pm Post subject: |
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Why would you not want to run an electric fuel pump on a carb without an oil pressure kill? |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Sat May 10, 2014 9:50 pm Post subject: |
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There's nothing to shut off the pump in a rollover. |
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Xophertony Rodeo Queen
Joined: 13 Oct 2005 Posts: 5304 Location: Portland, Oregon.
1988 Pontiac GTA
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Posted: Sun May 11, 2014 6:37 am Post subject: |
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Ah, thanks. So what shuts off fuel in a rollover on my TPI? |
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Alphius Peanut
Joined: 05 Sep 2006 Posts: 2429 Location: Grand Mound
1984 Chevrolet Camaro Z/28
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Posted: Sun May 11, 2014 6:57 am Post subject: |
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When the engine dies the ECM turns the fuel pump turns off 2 seconds later. _________________ 84 Camaro Z28 - LS1/T56
85 Silverado - Low and Slow |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Sun May 11, 2014 8:50 am Post subject: |
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Also with efi the injectors don't fire when the engine is not running. So there's no fuel spilling. With a carb unless you are exactly upside down, the float won't close and if the pump is runniing it will be pumping fuel out til the tank runs dry. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Sun May 11, 2014 8:56 am Post subject: |
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Mazda wired my fuel pump with carb, key on only. Just saying.
If the float boel is empty enjoy that long crank time while oil pressure builds. Enjoy finding a key on and starter engauged power circuit.
The pump needs to be on a relay. Not wired to ign power.
IIrc the tan wire goes to the oil pressure gauge. _________________ A redline a day keeps the carbon away! |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Sun May 11, 2014 9:12 am Post subject: |
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Just saying the reasoning. But my electric pump in the 74 isn't wired that way either. Guess i'm betting the odds it won't roll over. |
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aaron_sK Member
Joined: 23 Jan 2006 Posts: 8834 Location: Back in beautiful Tacompton
1987 Chevrolet Camaro IROC-Z
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Posted: Sun May 11, 2014 9:22 am Post subject: |
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Twilightoptics wrote: | Mazda wired my fuel pump with carb, key on only. Just saying. |
Didn't they also run it direct from the ignition switch back then? On my Mazda they triggered the fuel pump via the mass-air flappy door. Mazda electrical engineering is truly the worst.
I have always run a pressure switch with a carb. I never had a problem with bowls running dry, but that may have been because I had a Holley.
It's also worth noting that if it stalls on you and you don't get the ignition turned off right away you will flood it without the kill.
To me it's like running an electric fan off a manual switch. It will work fine until the one time you forget about it and then everything goes wrong. And for the $20 and a half hour of work it takes to do it right it's not a corner that is worth cutting IMO. |
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chevymad Master B
Joined: 11 Jan 2004 Posts: 5474
1987 Pontiac Formula
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Posted: Sun May 11, 2014 9:40 am Post subject: |
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If your regulator is set right you won't flood it. Most of the bosch flappy door injection setups use it to turn on the pump. I know toyota is that way as well. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Sun May 11, 2014 9:55 am Post subject: |
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They ran everything through the ign switch lol. _________________ A redline a day keeps the carbon away! |
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91camaro_rs Member
Joined: 03 Dec 2008 Posts: 1712 Location: Fox Island, Wa
1991 Chevrolet Camaro RS
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Posted: Sun May 11, 2014 2:42 pm Post subject: |
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So do I run the two extra wires off the pressure switch to fuel pump relay? And what kind of vacuum swotch for the lockup? _________________
'91 Camaro RS 5.7 TPI- 700r4- 3.27 posi- headers- chambered exhaust- |
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Al Hasse Member
Joined: 19 Nov 2005 Posts: 4379 Location: Bremerton, WA
1992 Chevrolet Camaro RS
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Posted: Sun May 11, 2014 6:26 pm Post subject: |
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Looking at a couple of wiring diagrams on Austin 3rd Gen, the tan wire goes to your gauge. The other two go to the fuel pump relay, the gray one on the ECM side (diagram doesn't indicate pin numbers/letters) and the orange one to the gauges fuse side. |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Sun May 11, 2014 6:29 pm Post subject: |
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TCI used to make a pretty good lockup setup. _________________ A redline a day keeps the carbon away! |
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83Z28BlackBetty Bam-Ba-Lam
Joined: 13 Mar 2006 Posts: 2083 Location: Aloha
1983 Chevrolet Camaro Z/28
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Posted: Mon May 12, 2014 10:09 am Post subject: |
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TCI makes a kit for the lock up, but its pretty easy to DIY if you can find the right pressrue switch. You need a vacuum adjustible pressure switch, run it to a vacuum line off the intake, and wire it in to the trans. So when in 4th gear (the 4th gear solenoid will close its circuit) and high vacuum aka low throttle pressure, cruising, (the vacuum switch will close its circuit) and it will activate the lockup on your trans. If not you will burn through a 700R4 in a hurry. Ask me how i know, I used to have a converted carbed 305... If you have quiestions let me know. ALso you can always ditch the electric fuel pump all together and bolt on a mechanical pump. They are like $20 and no wiring required.
~JAKE |
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Twilightoptics Hardcore (12sec Club)
Joined: 13 Jan 2004 Posts: 9191 Location: Auburn , WA
1987 Chevrolet Camaro IROC-Z
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Posted: Mon May 12, 2014 1:10 pm Post subject: |
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Jake you cant bolt a fuel pump into his engine. Tbi blocks are one oiece rear main blocks which dont have a hole for the fuel pump. Plus the fuel injected oe cams dont have a fuel pump drive lobe. _________________ A redline a day keeps the carbon away! |
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Alphius Peanut
Joined: 05 Sep 2006 Posts: 2429 Location: Grand Mound
1984 Chevrolet Camaro Z/28
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Posted: Mon May 12, 2014 4:34 pm Post subject: |
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I bolted a manual fuel pump up to an '87 TPI 1-piece RMS block with the stock cam and it worked fine. Maybe they got rid of the fuel pump lobe by '91 though. Just wanted to prove Paul wrong. _________________ 84 Camaro Z28 - LS1/T56
85 Silverado - Low and Slow |
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